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Author SHA1 Message Date
Anshuman Khandual
5dcfc6a1cc mm/mmap: drop arch_filter_pgprot() 
There are no platforms left which subscribe ARCH_HAS_FILTER_PGPROT.  Hence
drop generic arch_filter_pgprot() and also config ARCH_HAS_FILTER_PGPROT.

Link: https://lkml.kernel.org/r/20220414062125.609297-7-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-04-28 23:16:13 -07:00
Anshuman Khandual
67436193c2 mm/mmap: add new config ARCH_HAS_VM_GET_PAGE_PROT 
Patch series "mm/mmap: Drop arch_vm_get_page_prot() and arch_filter_pgprot()", v7.

protection_map[] is an array based construct that translates given
vm_flags combination.  This array contains page protection map, which is
populated by the platform via [__S000 ..  __S111] and [__P000 ..  __P111]
exported macros.  Primary usage for protection_map[] is for
vm_get_page_prot(), which is used to determine page protection value for a
given vm_flags.  vm_get_page_prot() implementation, could again call
platform overrides arch_vm_get_page_prot() and arch_filter_pgprot().  Some
platforms override protection_map[] that was originally built with
__SXXX/__PXXX with different runtime values.

Currently there are multiple layers of abstraction i.e __SXXX/__PXXX
macros , protection_map[], arch_vm_get_page_prot() and
arch_filter_pgprot() built between the platform and generic MM, finally
defining vm_get_page_prot().

Hence this series proposes to drop later two abstraction levels and
instead just move the responsibility of defining vm_get_page_prot() to the
platform (still utilizing generic protection_map[] array) itself making it
clean and simple.

This first introduces ARCH_HAS_VM_GET_PAGE_PROT which enables the
platforms to define custom vm_get_page_prot().  This starts converting
platforms that define the overrides arch_filter_pgprot() or
arch_vm_get_page_prot() which enables for those constructs to be dropped
off completely.

The series has been inspired from an earlier discuss with Christoph Hellwig

https://lore.kernel.org/all/1632712920-8171-1-git-send-email-anshuman.khandual@arm.com/


This patch (of 7):

Add a new config ARCH_HAS_VM_GET_PAGE_PROT, which when subscribed enables
a given platform to define its own vm_get_page_prot() but still utilizing
the generic protection_map[] array.

Link: https://lkml.kernel.org/r/20220414062125.609297-1-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/20220414062125.609297-2-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-04-28 23:16:12 -07:00
Anshuman Khandual
24e988c7fd mm: generalize ARCH_HAS_FILTER_PGPROT 
ARCH_HAS_FILTER_PGPROT config has duplicate definitions on platforms that
subscribe it.  Instead make it a generic config option which can be
selected on applicable platforms when required.

Link: https://lkml.kernel.org/r/1643004823-16441-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-03-24 19:06:51 -07:00
Linus Torvalds
9030fb0bb9 Folio changes for 5.18 
- Rewrite how munlock works to massively reduce the contention
    on i_mmap_rwsem (Hugh Dickins):
    https://lore.kernel.org/linux-mm/8e4356d-9622-a7f0-b2c-f116b5f2efea@google.com/
  - Sort out the page refcount mess for ZONE_DEVICE pages (Christoph Hellwig):
    https://lore.kernel.org/linux-mm/20220210072828.2930359-1-hch@lst.de/
  - Convert GUP to use folios and make pincount available for order-1
    pages. (Matthew Wilcox)
  - Convert a few more truncation functions to use folios (Matthew Wilcox)
  - Convert page_vma_mapped_walk to use PFNs instead of pages (Matthew Wilcox)
  - Convert rmap_walk to use folios (Matthew Wilcox)
  - Convert most of shrink_page_list() to use a folio (Matthew Wilcox)
  - Add support for creating large folios in readahead (Matthew Wilcox)
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Merge tag 'folio-5.18c' of git://git.infradead.org/users/willy/pagecache

Pull folio updates from Matthew Wilcox:

 - Rewrite how munlock works to massively reduce the contention on
   i_mmap_rwsem (Hugh Dickins):

     https://lore.kernel.org/linux-mm/8e4356d-9622-a7f0-b2c-f116b5f2efea@google.com/

 - Sort out the page refcount mess for ZONE_DEVICE pages (Christoph
   Hellwig):

     https://lore.kernel.org/linux-mm/20220210072828.2930359-1-hch@lst.de/

 - Convert GUP to use folios and make pincount available for order-1
   pages. (Matthew Wilcox)

 - Convert a few more truncation functions to use folios (Matthew
   Wilcox)

 - Convert page_vma_mapped_walk to use PFNs instead of pages (Matthew
   Wilcox)

 - Convert rmap_walk to use folios (Matthew Wilcox)

 - Convert most of shrink_page_list() to use a folio (Matthew Wilcox)

 - Add support for creating large folios in readahead (Matthew Wilcox)

* tag 'folio-5.18c' of git://git.infradead.org/users/willy/pagecache: (114 commits)
  mm/damon: minor cleanup for damon_pa_young
  selftests/vm/transhuge-stress: Support file-backed PMD folios
  mm/filemap: Support VM_HUGEPAGE for file mappings
  mm/readahead: Switch to page_cache_ra_order
  mm/readahead: Align file mappings for non-DAX
  mm/readahead: Add large folio readahead
  mm: Support arbitrary THP sizes
  mm: Make large folios depend on THP
  mm: Fix READ_ONLY_THP warning
  mm/filemap: Allow large folios to be added to the page cache
  mm: Turn can_split_huge_page() into can_split_folio()
  mm/vmscan: Convert pageout() to take a folio
  mm/vmscan: Turn page_check_references() into folio_check_references()
  mm/vmscan: Account large folios correctly
  mm/vmscan: Optimise shrink_page_list for non-PMD-sized folios
  mm/vmscan: Free non-shmem folios without splitting them
  mm/rmap: Constify the rmap_walk_control argument
  mm/rmap: Convert rmap_walk() to take a folio
  mm: Turn page_anon_vma() into folio_anon_vma()
  mm/rmap: Turn page_lock_anon_vma_read() into folio_lock_anon_vma_read()
  ...
 2022-03-22 17:03:12 -07:00
Linus Torvalds
3bf03b9a08 Merge branch 'akpm' (patches from Andrew) 
Merge updates from Andrew Morton:

 - A few misc subsystems: kthread, scripts, ntfs, ocfs2, block, and vfs

 - Most the MM patches which precede the patches in Willy's tree: kasan,
   pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
   sparsemem, vmalloc, pagealloc, memory-failure, mlock, hugetlb,
   userfaultfd, vmscan, compaction, mempolicy, oom-kill, migration, thp,
   cma, autonuma, psi, ksm, page-poison, madvise, memory-hotplug, rmap,
   zswap, uaccess, ioremap, highmem, cleanups, kfence, hmm, and damon.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (227 commits)
  mm/damon/sysfs: remove repeat container_of() in damon_sysfs_kdamond_release()
  Docs/ABI/testing: add DAMON sysfs interface ABI document
  Docs/admin-guide/mm/damon/usage: document DAMON sysfs interface
  selftests/damon: add a test for DAMON sysfs interface
  mm/damon/sysfs: support DAMOS stats
  mm/damon/sysfs: support DAMOS watermarks
  mm/damon/sysfs: support schemes prioritization
  mm/damon/sysfs: support DAMOS quotas
  mm/damon/sysfs: support DAMON-based Operation Schemes
  mm/damon/sysfs: support the physical address space monitoring
  mm/damon/sysfs: link DAMON for virtual address spaces monitoring
  mm/damon: implement a minimal stub for sysfs-based DAMON interface
  mm/damon/core: add number of each enum type values
  mm/damon/core: allow non-exclusive DAMON start/stop
  Docs/damon: update outdated term 'regions update interval'
  Docs/vm/damon/design: update DAMON-Idle Page Tracking interference handling
  Docs/vm/damon: call low level monitoring primitives the operations
  mm/damon: remove unnecessary CONFIG_DAMON option
  mm/damon/paddr,vaddr: remove damon_{p,v}a_{target_valid,set_operations}()
  mm/damon/dbgfs-test: fix is_target_id() change
  ...
 2022-03-22 16:11:53 -07:00
Anshuman Khandual
07431506e8 mm/hugetlb: generalize ARCH_WANT_GENERAL_HUGETLB 
ARCH_WANT_GENERAL_HUGETLB config has duplicate definitions on platforms
that subscribe it.  Instead make it a generic config option which can be
selected on applicable platforms when required.

Link: https://lkml.kernel.org/r/1643718465-4324-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-03-22 15:57:08 -07:00
David Hildenbrand
b3d40a2b6d mm: enforce pageblock_order < MAX_ORDER 
Some places in the kernel don't really expect pageblock_order >=
MAX_ORDER, and it looks like this is only possible in corner cases:

1) CONFIG_DEFERRED_STRUCT_PAGE_INIT we'll end up freeing pageblock_order
   pages via __free_pages_core(), which cannot possibly work.

2) find_zone_movable_pfns_for_nodes() will roundup the ZONE_MOVABLE
   start PFN to MAX_ORDER_NR_PAGES. Consequently with a bigger
   pageblock_order, we could have a single pageblock partially managed by
   two zones.

3) compaction code runs into __fragmentation_index() with order
   >= MAX_ORDER, when checking WARN_ON_ONCE(order >= MAX_ORDER). [1]

4) mm/page_reporting.c won't be reporting any pages with default
   page_reporting_order == pageblock_order, as we'll be skipping the
   reporting loop inside page_reporting_process_zone().

5) __rmqueue_fallback() will never be able to steal with
   ALLOC_NOFRAGMENT.

pageblock_order >= MAX_ORDER is weird either way: it's a pure
optimization for making alloc_contig_range(), as used for allcoation of
gigantic pages, a little more reliable to succeed.  However, if there is
demand for somewhat reliable allocation of gigantic pages, affected
setups should be using CMA or boottime allocations instead.

So let's make sure that pageblock_order < MAX_ORDER and simplify.

[1] https://lkml.kernel.org/r/87r189a2ks.fsf@linux.ibm.com

Link: https://lkml.kernel.org/r/20220214174132.219303-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: John Garry via iommu <iommu@lists.linux-foundation.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-03-22 15:57:06 -07:00
Christoph Hellwig
d90a25f86d mm: build migrate_vma_* for all configs with ZONE_DEVICE support 
This code will be used for device coherent memory as well in a bit,
so relax the ifdef a bit.

Link: https://lkml.kernel.org/r/20220210072828.2930359-15-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Tested-by: "Sierra Guiza, Alejandro (Alex)" <alex.sierra@amd.com>

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Christian Knig <christian.koenig@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
 2022-03-03 12:47:33 -05:00
Christoph Hellwig
76cbbead25 mm: move the migrate_vma_* device migration code into its own file 
Split the code used to migrate to and from ZONE_DEVICE memory from
migrate.c into a new file.

Link: https://lkml.kernel.org/r/20220210072828.2930359-14-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: "Sierra Guiza, Alejandro (Alex)" <alex.sierra@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Christian Knig <christian.koenig@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
 2022-03-03 12:47:33 -05:00
Christoph Hellwig
27674ef6c7 mm: remove the extra ZONE_DEVICE struct page refcount 
ZONE_DEVICE struct pages have an extra reference count that complicates
the code for put_page() and several places in the kernel that need to
check the reference count to see that a page is not being used (gup,
compaction, migration, etc.). Clean up the code so the reference count
doesn't need to be treated specially for ZONE_DEVICE pages.

Note that this excludes the special idle page wakeup for fsdax pages,
which still happens at refcount 1.  This is a separate issue and will
be sorted out later.  Given that only fsdax pages require the
notifiacation when the refcount hits 1 now, the PAGEMAP_OPS Kconfig
symbol can go away and be replaced with a FS_DAX check for this hook
in the put_page fastpath.

Based on an earlier patch from Ralph Campbell <rcampbell@nvidia.com>.

Link: https://lkml.kernel.org/r/20220210072828.2930359-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Tested-by: "Sierra Guiza, Alejandro (Alex)" <alex.sierra@amd.com>

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Christian Knig <christian.koenig@amd.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
 2022-03-03 12:47:33 -05:00
Kees Cook
2792d84e6d usercopy: Check valid lifetime via stack depth 
One of the things that CONFIG_HARDENED_USERCOPY sanity-checks is whether
an object that is about to be copied to/from userspace is overlapping
the stack at all. If it is, it performs a number of inexpensive
bounds checks. One of the finer-grained checks is whether an object
crosses stack frames within the stack region. Doing this on x86 with
CONFIG_FRAME_POINTER was cheap/easy. Doing it with ORC was deemed too
heavy, and was left out (a while ago), leaving the courser whole-stack
check.

The LKDTM tests USERCOPY_STACK_FRAME_TO and USERCOPY_STACK_FRAME_FROM
try to exercise these cross-frame cases to validate the defense is
working. They have been failing ever since ORC was added (which was
expected). While Muhammad was investigating various LKDTM failures[1],
he asked me for additional details on them, and I realized that when
exact stack frame boundary checking is not available (i.e. everything
except x86 with FRAME_POINTER), it could check if a stack object is at
least "current depth valid", in the sense that any object within the
stack region but not between start-of-stack and current_stack_pointer
should be considered unavailable (i.e. its lifetime is from a call no
longer present on the stack).

Introduce ARCH_HAS_CURRENT_STACK_POINTER to track which architectures
have actually implemented the common global register alias.

Additionally report usercopy bounds checking failures with an offset
from current_stack_pointer, which may assist with diagnosing failures.

The LKDTM USERCOPY_STACK_FRAME_TO and USERCOPY_STACK_FRAME_FROM tests
(once slightly adjusted in a separate patch) pass again with this fixed.

[1] https://github.com/kernelci/kernelci-project/issues/84

Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
v1: https://lore.kernel.org/lkml/20220216201449.2087956-1-keescook@chromium.org
v2: https://lore.kernel.org/lkml/20220224060342.1855457-1-keescook@chromium.org
v3: https://lore.kernel.org/lkml/20220225173345.3358109-1-keescook@chromium.org
v4: - improve commit log (akpm)
 2022-02-25 18:20:11 -08:00
Christoph Hellwig
6e61dde82e mm: hide the FRONTSWAP Kconfig symbol 
Select FRONTSWAP from ZSWAP instead of prompting for it.

Link: https://lkml.kernel.org/r/20211224062246.1258487-14-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-01-22 08:33:38 +02:00
Christoph Hellwig
0a4ee51818 mm: remove cleancache 
Patch series "remove Xen tmem leftovers".

Since the removal of the Xen tmem driver in 2019, the cleancache hooks
are entirely unused, as are large parts of frontswap.  This series
against linux-next (with the folio changes included) removes
cleancaches, and cuts down frontswap to the bits actually used by zswap.

This patch (of 13):

The cleancache subsystem is unused since the removal of Xen tmem driver
in commit 814bbf49dc ("xen: remove tmem driver").

[akpm@linux-foundation.org: remove now-unreachable code]

Link: https://lkml.kernel.org/r/20211224062246.1258487-1-hch@lst.de
Link: https://lkml.kernel.org/r/20211224062246.1258487-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-01-22 08:33:38 +02:00
Linus Torvalds
f4484d138b Merge branch 'akpm' (patches from Andrew) 
Merge more updates from Andrew Morton:
 "55 patches.

  Subsystems affected by this patch series: percpu, procfs, sysctl,
  misc, core-kernel, get_maintainer, lib, checkpatch, binfmt, nilfs2,
  hfs, fat, adfs, panic, delayacct, kconfig, kcov, and ubsan"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (55 commits)
  lib: remove redundant assignment to variable ret
  ubsan: remove CONFIG_UBSAN_OBJECT_SIZE
  kcov: fix generic Kconfig dependencies if ARCH_WANTS_NO_INSTR
  lib/Kconfig.debug: make TEST_KMOD depend on PAGE_SIZE_LESS_THAN_256KB
  btrfs: use generic Kconfig option for 256kB page size limit
  arch/Kconfig: split PAGE_SIZE_LESS_THAN_256KB from PAGE_SIZE_LESS_THAN_64KB
  configs: introduce debug.config for CI-like setup
  delayacct: track delays from memory compact
  Documentation/accounting/delay-accounting.rst: add thrashing page cache and direct compact
  delayacct: cleanup flags in struct task_delay_info and functions use it
  delayacct: fix incomplete disable operation when switch enable to disable
  delayacct: support swapin delay accounting for swapping without blkio
  panic: remove oops_id
  panic: use error_report_end tracepoint on warnings
  fs/adfs: remove unneeded variable make code cleaner
  FAT: use io_schedule_timeout() instead of congestion_wait()
  hfsplus: use struct_group_attr() for memcpy() region
  nilfs2: remove redundant pointer sbufs
  fs/binfmt_elf: use PT_LOAD p_align values for static PIE
  const_structs.checkpatch: add frequently used ops structs
  ...
 2022-01-20 10:41:01 +02:00
Kefeng Wang
7ecd19cfdf mm: percpu: generalize percpu related config 
Patch series "mm: percpu: Cleanup percpu first chunk function".

When supporting page mapping percpu first chunk allocator on arm64, we
found there are lots of duplicated codes in percpu embed/page first chunk
allocator.  This patchset is aimed to cleanup them and should no function
change.

The currently supported status about 'embed' and 'page' in Archs shows
below,

	embed: NEED_PER_CPU_PAGE_FIRST_CHUNK
	page:  NEED_PER_CPU_EMBED_FIRST_CHUNK

		embed	page
	------------------------
	arm64	  Y	 Y
	mips	  Y	 N
	powerpc	  Y	 Y
	riscv	  Y	 N
	sparc	  Y	 Y
	x86	  Y	 Y
	------------------------

There are two interfaces about percpu first chunk allocator,

 extern int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
                                size_t atom_size,
                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
-                               pcpu_fc_alloc_fn_t alloc_fn,
-                               pcpu_fc_free_fn_t free_fn);
+                               pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);

 extern int __init pcpu_page_first_chunk(size_t reserved_size,
-                               pcpu_fc_alloc_fn_t alloc_fn,
-                               pcpu_fc_free_fn_t free_fn,
-                               pcpu_fc_populate_pte_fn_t populate_pte_fn);
+                               pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);

The pcpu_fc_alloc_fn_t/pcpu_fc_free_fn_t is killed, we provide generic
pcpu_fc_alloc() and pcpu_fc_free() function, which are called in the
pcpu_embed/page_first_chunk().

1) For pcpu_embed_first_chunk(), pcpu_fc_cpu_to_node_fn_t is needed to be
   provided when archs supported NUMA.

2) For pcpu_page_first_chunk(), the pcpu_fc_populate_pte_fn_t is killed too,
   a generic pcpu_populate_pte() which marked '__weak' is provided, if you
   need a different function to populate pte on the arch(like x86), please
   provide its own implementation.

[1] https://github.com/kevin78/linux.git percpu-cleanup

This patch (of 4):

The HAVE_SETUP_PER_CPU_AREA/NEED_PER_CPU_EMBED_FIRST_CHUNK/
NEED_PER_CPU_PAGE_FIRST_CHUNK/USE_PERCPU_NUMA_NODE_ID configs, which have
duplicate definitions on platforms that subscribe it.

Move them into mm, drop these redundant definitions and instead just
select it on applicable platforms.

Link: https://lkml.kernel.org/r/20211216112359.103822-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20211216112359.103822-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-01-20 08:52:52 +02:00
Colin Cross
9a10064f56 mm: add a field to store names for private anonymous memory 
In many userspace applications, and especially in VM based applications
like Android uses heavily, there are multiple different allocators in
use.  At a minimum there is libc malloc and the stack, and in many cases
there are libc malloc, the stack, direct syscalls to mmap anonymous
memory, and multiple VM heaps (one for small objects, one for big
objects, etc.).  Each of these layers usually has its own tools to
inspect its usage; malloc by compiling a debug version, the VM through
heap inspection tools, and for direct syscalls there is usually no way
to track them.

On Android we heavily use a set of tools that use an extended version of
the logic covered in Documentation/vm/pagemap.txt to walk all pages
mapped in userspace and slice their usage by process, shared (COW) vs.
unique mappings, backing, etc.  This can account for real physical
memory usage even in cases like fork without exec (which Android uses
heavily to share as many private COW pages as possible between
processes), Kernel SamePage Merging, and clean zero pages.  It produces
a measurement of the pages that only exist in that process (USS, for
unique), and a measurement of the physical memory usage of that process
with the cost of shared pages being evenly split between processes that
share them (PSS).

If all anonymous memory is indistinguishable then figuring out the real
physical memory usage (PSS) of each heap requires either a pagemap
walking tool that can understand the heap debugging of every layer, or
for every layer's heap debugging tools to implement the pagemap walking
logic, in which case it is hard to get a consistent view of memory
across the whole system.

Tracking the information in userspace leads to all sorts of problems.
It either needs to be stored inside the process, which means every
process has to have an API to export its current heap information upon
request, or it has to be stored externally in a filesystem that somebody
needs to clean up on crashes.  It needs to be readable while the process
is still running, so it has to have some sort of synchronization with
every layer of userspace.  Efficiently tracking the ranges requires
reimplementing something like the kernel vma trees, and linking to it
from every layer of userspace.  It requires more memory, more syscalls,
more runtime cost, and more complexity to separately track regions that
the kernel is already tracking.

This patch adds a field to /proc/pid/maps and /proc/pid/smaps to show a
userspace-provided name for anonymous vmas.  The names of named
anonymous vmas are shown in /proc/pid/maps and /proc/pid/smaps as
[anon:<name>].

Userspace can set the name for a region of memory by calling

   prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name)

Setting the name to NULL clears it.  The name length limit is 80 bytes
including NUL-terminator and is checked to contain only printable ascii
characters (including space), except '[',']','\','$' and '`'.

Ascii strings are being used to have a descriptive identifiers for vmas,
which can be understood by the users reading /proc/pid/maps or
/proc/pid/smaps.  Names can be standardized for a given system and they
can include some variable parts such as the name of the allocator or a
library, tid of the thread using it, etc.

The name is stored in a pointer in the shared union in vm_area_struct
that points to a null terminated string.  Anonymous vmas with the same
name (equivalent strings) and are otherwise mergeable will be merged.
The name pointers are not shared between vmas even if they contain the
same name.  The name pointer is stored in a union with fields that are
only used on file-backed mappings, so it does not increase memory usage.

CONFIG_ANON_VMA_NAME kernel configuration is introduced to enable this
feature.  It keeps the feature disabled by default to prevent any
additional memory overhead and to avoid confusing procfs parsers on
systems which are not ready to support named anonymous vmas.

The patch is based on the original patch developed by Colin Cross, more
specifically on its latest version [1] posted upstream by Sumit Semwal.
It used a userspace pointer to store vma names.  In that design, name
pointers could be shared between vmas.  However during the last
upstreaming attempt, Kees Cook raised concerns [2] about this approach
and suggested to copy the name into kernel memory space, perform
validity checks [3] and store as a string referenced from
vm_area_struct.

One big concern is about fork() performance which would need to strdup
anonymous vma names.  Dave Hansen suggested experimenting with
worst-case scenario of forking a process with 64k vmas having longest
possible names [4].  I ran this experiment on an ARM64 Android device
and recorded a worst-case regression of almost 40% when forking such a
process.

This regression is addressed in the followup patch which replaces the
pointer to a name with a refcounted structure that allows sharing the
name pointer between vmas of the same name.  Instead of duplicating the
string during fork() or when splitting a vma it increments the refcount.

[1] https://lore.kernel.org/linux-mm/20200901161459.11772-4-sumit.semwal@linaro.org/
[2] https://lore.kernel.org/linux-mm/202009031031.D32EF57ED@keescook/
[3] https://lore.kernel.org/linux-mm/202009031022.3834F692@keescook/
[4] https://lore.kernel.org/linux-mm/5d0358ab-8c47-2f5f-8e43-23b89d6a8e95@intel.com/

Changes for prctl(2) manual page (in the options section):

PR_SET_VMA
	Sets an attribute specified in arg2 for virtual memory areas
	starting from the address specified in arg3 and spanning the
	size specified	in arg4. arg5 specifies the value of the attribute
	to be set. Note that assigning an attribute to a virtual memory
	area might prevent it from being merged with adjacent virtual
	memory areas due to the difference in that attribute's value.

	Currently, arg2 must be one of:

	PR_SET_VMA_ANON_NAME
		Set a name for anonymous virtual memory areas. arg5 should
		be a pointer to a null-terminated string containing the
		name. The name length including null byte cannot exceed
		80 bytes. If arg5 is NULL, the name of the appropriate
		anonymous virtual memory areas will be reset. The name
		can contain only printable ascii characters (including
                space), except '[',']','\','$' and '`'.

                This feature is available only if the kernel is built with
                the CONFIG_ANON_VMA_NAME option enabled.

[surenb@google.com: docs: proc.rst: /proc/PID/maps: fix malformed table]
  Link: https://lkml.kernel.org/r/20211123185928.2513763-1-surenb@google.com
[surenb: rebased over v5.15-rc6, replaced userpointer with a kernel copy,
 added input sanitization and CONFIG_ANON_VMA_NAME config. The bulk of the
 work here was done by Colin Cross, therefore, with his permission, keeping
 him as the author]

Link: https://lkml.kernel.org/r/20211019215511.3771969-2-surenb@google.com
Signed-off-by: Colin Cross <ccross@google.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Glauber <jan.glauber@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rob Landley <rob@landley.net>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Shaohua Li <shli@fusionio.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-01-15 16:30:27 +02:00
Vladimir Murzin
3583521aab percpu: km: ensure it is used with NOMMU (either UP or SMP) 
Currently, NOMMU pull km allocator via !SMP dependency because most of
them are UP, yet for SMP+NOMMU vm allocator gets pulled which:

* may lead to broken build [1]
* ...or not working runtime due to [2]

It looks like SMP+NOMMU case was overlooked in bbddff0545 ("percpu:
use percpu allocator on UP too") so restore that.

[1]
For ARM SMP+NOMMU (R-class cores)

arm-none-linux-gnueabihf-ld: mm/percpu.o: in function `pcpu_post_unmap_tlb_flush':
mm/percpu-vm.c:188: undefined reference to `flush_tlb_kernel_range'

[2]
static inline
int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages, unsigned int page_shift)
{
       return -EINVAL;
}

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Rob Landley <rob@landley.net>
Tested-by: Rich Felker <dalias@libc.org>
[Dennis: use depends instead of default for condition]
Signed-off-by: Dennis Zhou <dennis@kernel.org>
 2021-12-06 12:45:09 -05:00
Ard Biesheuvel
825c43f50e kmap_local: don't assume kmap PTEs are linear arrays in memory 
The kmap_local conversion broke the ARM architecture, because the new
code assumes that all PTEs used for creating kmaps form a linear array
in memory, and uses array indexing to look up the kmap PTE belonging to
a certain kmap index.

On ARM, this cannot work, not only because the PTE pages may be
non-adjacent in memory, but also because ARM/!LPAE interleaves hardware
entries and extended entries (carrying software-only bits) in a way that
is not compatible with array indexing.

Fortunately, this only seems to affect configurations with more than 8
CPUs, due to the way the per-CPU kmap slots are organized in memory.

Work around this by permitting an architecture to set a Kconfig symbol
that signifies that the kmap PTEs do not form a lineary array in memory,
and so the only way to locate the appropriate one is to walk the page
tables.

Link: https://lore.kernel.org/linux-arm-kernel/20211026131249.3731275-1-ardb@kernel.org/
Link: https://lkml.kernel.org/r/20211116094737.7391-1-ardb@kernel.org
Fixes: 2a15ba82fa ("ARM: highmem: Switch to generic kmap atomic")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reported-by: Quanyang Wang <quanyang.wang@windriver.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-11-20 10:35:54 -08:00
David Hildenbrand
a9e7b8d4f6 kernel/resource: disallow access to exclusive system RAM regions 
virtio-mem dynamically exposes memory inside a device memory region as
system RAM to Linux, coordinating with the hypervisor which parts are
actually "plugged" and consequently usable/accessible.

On the one hand, the virtio-mem driver adds/removes whole memory blocks,
creating/removing busy IORESOURCE_SYSTEM_RAM resources, on the other
hand, it logically (un)plugs memory inside added memory blocks,
dynamically either exposing them to the buddy or hiding them from the
buddy and marking them PG_offline.

In contrast to physical devices, like a DIMM, the virtio-mem driver is
required to actually make use of any of the device-provided memory,
because it performs the handshake with the hypervisor.  virtio-mem
memory cannot simply be access via /dev/mem without a driver.

There is no safe way to:
a) Access plugged memory blocks via /dev/mem, as they might contain
   unplugged holes or might get silently unplugged by the virtio-mem
   driver and consequently turned inaccessible.
b) Access unplugged memory blocks via /dev/mem because the virtio-mem
   driver is required to make them actually accessible first.

The virtio-spec states that unplugged memory blocks MUST NOT be written,
and only selected unplugged memory blocks MAY be read.  We want to make
sure, this is the case in sane environments -- where the virtio-mem driver
was loaded.

We want to make sure that in a sane environment, nobody "accidentially"
accesses unplugged memory inside the device managed region.  For example,
a user might spot a memory region in /proc/iomem and try accessing it via
/dev/mem via gdb or dumping it via something else.  By the time the mmap()
happens, the memory might already have been removed by the virtio-mem
driver silently: the mmap() would succeeed and user space might
accidentially access unplugged memory.

So once the driver was loaded and detected the device along the
device-managed region, we just want to disallow any access via /dev/mem to
it.

In an ideal world, we would mark the whole region as busy ("owned by a
driver") and exclude it; however, that would be wrong, as we don't really
have actual system RAM at these ranges added to Linux ("busy system RAM").
Instead, we want to mark such ranges as "not actual busy system RAM but
still soft-reserved and prepared by a driver for future use."

Let's teach iomem_is_exclusive() to reject access to any range with
"IORESOURCE_SYSTEM_RAM | IORESOURCE_EXCLUSIVE", even if not busy and even
if "iomem=relaxed" is set.  Introduce EXCLUSIVE_SYSTEM_RAM to make it
easier for applicable drivers to depend on this setting in their Kconfig.

For now, there are no applicable ranges and we'll modify virtio-mem next
to properly set IORESOURCE_EXCLUSIVE on the parent resource container it
creates to contain all actual busy system RAM added via
add_memory_driver_managed().

Link: https://lkml.kernel.org/r/20210920142856.17758-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-11-09 10:02:52 -08:00
David Hildenbrand
7ec58a2b94 mm/memory_hotplug: restrict CONFIG_MEMORY_HOTPLUG to 64 bit 
32 bit support is broken in various ways: for example, we can online
memory that should actually go to ZONE_HIGHMEM to ZONE_MOVABLE or in
some cases even to one of the other kernel zones.

We marked it BROKEN in commit b59d02ed08 ("mm/memory_hotplug: disable
the functionality for 32b") almost one year ago.  According to that
commit it might be broken at least since 2017.  Further, there is hardly
a sane use case nowadays.

Let's just depend completely on 64bit, dropping the "BROKEN" dependency
to make clear that we are not going to support it again.  Next, we'll
remove some HIGHMEM leftovers from memory hotplug code to clean up.

Link: https://lkml.kernel.org/r/20210929143600.49379-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-11-06 13:30:42 -07:00
David Hildenbrand
50f9481ed9 mm/memory_hotplug: remove CONFIG_MEMORY_HOTPLUG_SPARSE 
CONFIG_MEMORY_HOTPLUG depends on CONFIG_SPARSEMEM, so there is no need for
CONFIG_MEMORY_HOTPLUG_SPARSE anymore; adjust all instances to use
CONFIG_MEMORY_HOTPLUG and remove CONFIG_MEMORY_HOTPLUG_SPARSE.

Link: https://lkml.kernel.org/r/20210929143600.49379-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>	[kselftest]
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-11-06 13:30:42 -07:00
David Hildenbrand
71b6f2dda8 mm/memory_hotplug: remove CONFIG_X86_64_ACPI_NUMA dependency from CONFIG_MEMORY_HOTPLUG 
Patch series "mm/memory_hotplug: Kconfig and 32 bit cleanups".

Some cleanups around CONFIG_MEMORY_HOTPLUG, including removing 32 bit
leftovers of memory hotplug support.

This patch (of 6):

SPARSEMEM is the only possible memory model for x86-64, FLATMEM is not
possible:

	config ARCH_FLATMEM_ENABLE
		def_bool y
		depends on X86_32 && !NUMA

And X86_64_ACPI_NUMA (obviously) only supports x86-64:

	config X86_64_ACPI_NUMA
		def_bool y
		depends on X86_64 && NUMA && ACPI && PCI

Let's just remove the CONFIG_X86_64_ACPI_NUMA dependency, as it does no
longer make sense.

Link: https://lkml.kernel.org/r/20210929143600.49379-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alex Shi <alexs@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-11-06 13:30:42 -07:00
Sebastian Andrzej Siewior
554b0f3ca6 mm: disable NUMA_BALANCING_DEFAULT_ENABLED and TRANSPARENT_HUGEPAGE on PREEMPT_RT 
TRANSPARENT_HUGEPAGE:
  There are potential non-deterministic delays to an RT thread if a
  critical memory region is not THP-aligned and a non-RT buffer is
  located in the same hugepage-aligned region. It's also possible for an
  unrelated thread to migrate pages belonging to an RT task incurring
  unexpected page faults due to memory defragmentation even if
  khugepaged is disabled.

Regular HUGEPAGEs are not affected by this can be used.

NUMA_BALANCING:
  There is a non-deterministic delay to mark PTEs PROT_NONE to gather
  NUMA fault samples, increased page faults of regions even if mlocked
  and non-deterministic delays when migrating pages.

[Mel Gorman worded 99% of the commit description].

Link: https://lore.kernel.org/all/20200304091159.GN3818@techsingularity.net/
Link: https://lore.kernel.org/all/20211026165100.ahz5bkx44lrrw5pt@linutronix.de/
Link: https://lkml.kernel.org/r/20211028143327.hfbxjze7palrpfgp@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-11-06 13:30:33 -07:00
SeongJae Park
1c676e0d9b mm/idle_page_tracking: make PG_idle reusable 
PG_idle and PG_young allow the two PTE Accessed bit users, Idle Page
Tracking and the reclaim logic concurrently work while not interfering
with each other.  That is, when they need to clear the Accessed bit, they
set PG_young to represent the previous state of the bit, respectively.
And when they need to read the bit, if the bit is cleared, they further
read the PG_young to know whether the other has cleared the bit meanwhile
or not.

For yet another user of the PTE Accessed bit, we could add another page
flag, or extend the mechanism to use the flags.  For the DAMON usecase,
however, we don't need to do that just yet.  IDLE_PAGE_TRACKING and DAMON
are mutually exclusive, so there's only ever going to be one user of the
current set of flags.

In this commit, we split out the CONFIG options to allow for the use of
PG_young and PG_idle outside of idle page tracking.

In the next commit, DAMON's reference implementation of the virtual memory
address space monitoring primitives will use it.

[sjpark@amazon.de: set PAGE_EXTENSION for non-64BIT]
  Link: https://lkml.kernel.org/r/20210806095153.6444-1-sj38.park@gmail.com
[akpm@linux-foundation.org: tweak Kconfig text]
[sjpark@amazon.de: hide PAGE_IDLE_FLAG from users]
  Link: https://lkml.kernel.org/r/20210813081238.34705-1-sj38.park@gmail.com

Link: https://lkml.kernel.org/r/20210716081449.22187-5-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-09-08 11:50:24 -07:00
SeongJae Park
2224d84854 mm: introduce Data Access MONitor (DAMON) 
Patch series "Introduce Data Access MONitor (DAMON)", v34.

Introduction
============

DAMON is a data access monitoring framework for the Linux kernel.  The
core mechanisms of DAMON called 'region based sampling' and 'adaptive
regions adjustment' (refer to 'mechanisms.rst' in the 11th patch of this
patchset for the detail) make it

- accurate (The monitored information is useful for DRAM level memory
  management.  It might not appropriate for Cache-level accuracy,
  though.),

- light-weight (The monitoring overhead is low enough to be applied
  online while making no impact on the performance of the target
  workloads.), and

- scalable (the upper-bound of the instrumentation overhead is
  controllable regardless of the size of target workloads.).

Using this framework, therefore, several memory management mechanisms such
as reclamation and THP can be optimized to aware real data access
patterns.  Experimental access pattern aware memory management
optimization works that incurring high instrumentation overhead will be
able to have another try.

Though DAMON is for kernel subsystems, it can be easily exposed to the
user space by writing a DAMON-wrapper kernel subsystem.  Then, user space
users who have some special workloads will be able to write personalized
tools or applications for deeper understanding and specialized
optimizations of their systems.

DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].

[1] https://github.com/amazonlinux/linux/tree/amazon-5.4.y/master/mm/damon
[2] https://github.com/amazonlinux/linux/tree/amazon-5.10.y/master/mm/damon

The userspace tool[1] is available, released under GPLv2, and actively
being maintained.  I am also planning to implement another basic user
interface in perf[2].  Also, the basic test suite for DAMON is available
under GPLv2[3].

[1] https://github.com/awslabs/damo
[2] https://lore.kernel.org/linux-mm/20210107120729.22328-1-sjpark@amazon.com/
[3] https://github.com/awslabs/damon-tests

Long-term Plan
--------------

DAMON is a part of a project called Data Access-aware Operating System
(DAOS).  As the name implies, I want to improve the performance and
efficiency of systems using fine-grained data access patterns.  The
optimizations are for both kernel and user spaces.  I will therefore
modify or create kernel subsystems, export some of those to user space and
implement user space library / tools.  Below shows the layers and
components for the project.

    ---------------------------------------------------------------------------
    Primitives:     PTE Accessed bit, PG_idle, rmap, (Intel CMT), ...
    Framework:      DAMON
    Features:       DAMOS, virtual addr, physical addr, ...
    Applications:   DAMON-debugfs, (DARC), ...
    ^^^^^^^^^^^^^^^^^^^^^^^    KERNEL SPACE    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    Raw Interface:  debugfs, (sysfs), (damonfs), tracepoints, (sys_damon), ...

    vvvvvvvvvvvvvvvvvvvvvvv    USER SPACE      vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
    Library:        (libdamon), ...
    Tools:          DAMO, (perf), ...
    ---------------------------------------------------------------------------

The components in parentheses or marked as '...' are not implemented yet
but in the future plan.  IOW, those are the TODO tasks of DAOS project.
For more detail, please refer to the plans:
https://lore.kernel.org/linux-mm/20201202082731.24828-1-sjpark@amazon.com/

Evaluations
===========

We evaluated DAMON's overhead, monitoring quality and usefulness using 24
realistic workloads on my QEMU/KVM based virtual machine running a kernel
that v24 DAMON patchset is applied.

DAMON is lightweight.  It increases system memory usage by 0.39% and slows
target workloads down by 1.16%.

DAMON is accurate and useful for memory management optimizations.  An
experimental DAMON-based operation scheme for THP, namely 'ethp', removes
76.15% of THP memory overheads while preserving 51.25% of THP speedup.
Another experimental DAMON-based 'proactive reclamation' implementation,
'prcl', reduces 93.38% of residential sets and 23.63% of system memory
footprint while incurring only 1.22% runtime overhead in the best case
(parsec3/freqmine).

NOTE that the experimental THP optimization and proactive reclamation are
not for production but only for proof of concepts.

Please refer to the official document[1] or "Documentation/admin-guide/mm:
Add a document for DAMON" patch in this patchset for detailed evaluation
setup and results.

[1] https://damonitor.github.io/doc/html/latest-damon/admin-guide/mm/damon/eval.html

Real-world User Story
=====================

In summary, DAMON has used on production systems and proved its usefulness.

DAMON as a profiler
-------------------

We analyzed characteristics of a large scale production systems of our
customers using DAMON.  The systems utilize 70GB DRAM and 36 CPUs.  From
this, we were able to find interesting things below.

There were obviously different access pattern under idle workload and
active workload.  Under the idle workload, it accessed large memory
regions with low frequency, while the active workload accessed small
memory regions with high freuqnecy.

DAMON found a 7GB memory region that showing obviously high access
frequency under the active workload.  We believe this is the
performance-effective working set and need to be protected.

There was a 4KB memory region that showing highest access frequency under
not only active but also idle workloads.  We think this must be a hottest
code section like thing that should never be paged out.

For this analysis, DAMON used only 0.3-1% of single CPU time.  Because we
used recording-based analysis, it consumed about 3-12 MB of disk space per
20 minutes.  This is only small amount of disk space, but we can further
reduce the disk usage by using non-recording-based DAMON features.  I'd
like to argue that only DAMON can do such detailed analysis (finding 4KB
highest region in 70GB memory) with the light overhead.

DAMON as a system optimization tool
-----------------------------------

We also found below potential performance problems on the systems and made
DAMON-based solutions.

The system doesn't want to make the workload suffer from the page
reclamation and thus it utilizes enough DRAM but no swap device.  However,
we found the system is actively reclaiming file-backed pages, because the
system has intensive file IO.  The file IO turned out to be not
performance critical for the workload, but the customer wanted to ensure
performance critical file-backed pages like code section to not mistakenly
be evicted.

Using direct IO should or `mlock()` would be a straightforward solution,
but modifying the user space code is not easy for the customer.
Alternatively, we could use DAMON-based operation scheme[1].  By using it,
we can ask DAMON to track access frequency of each region and make
'process_madvise(MADV_WILLNEED)[2]' call for regions having specific size
and access frequency for a time interval.

We also found the system is having high number of TLB misses.  We tried
'always' THP enabled policy and it greatly reduced TLB misses, but the
page reclamation also been more frequent due to the THP internal
fragmentation caused memory bloat.  We could try another DAMON-based
operation scheme that applies 'MADV_HUGEPAGE' to memory regions having
>=2MB size and high access frequency, while applying 'MADV_NOHUGEPAGE' to
regions having <2MB size and low access frequency.

We do not own the systems so we only reported the analysis results and
possible optimization solutions to the customers.  The customers satisfied
about the analysis results and promised to try the optimization guides.

[1] https://lore.kernel.org/linux-mm/20201006123931.5847-1-sjpark@amazon.com/
[2] https://lore.kernel.org/linux-api/20200622192900.22757-4-minchan@kernel.org/

Comparison with Idle Page Tracking
==================================

Idle Page Tracking allows users to set and read idleness of pages using a
bitmap file which represents each page with each bit of the file.  One
recommended usage of it is working set size detection.  Users can do that
by

    1. find PFN of each page for workloads in interest,
    2. set all the pages as idle by doing writes to the bitmap file,
    3. wait until the workload accesses its working set, and
    4. read the idleness of the pages again and count pages became not idle.

NOTE: While Idle Page Tracking is for user space users, DAMON is primarily
designed for kernel subsystems though it can easily exposed to the user
space.  Hence, this section only assumes such user space use of DAMON.

For what use cases Idle Page Tracking would be better?
------------------------------------------------------

1. Flexible usecases other than hotness monitoring.

Because Idle Page Tracking allows users to control the primitive (Page
idleness) by themselves, Idle Page Tracking users can do anything they
want.  Meanwhile, DAMON is primarily designed to monitor the hotness of
each memory region.  For this, DAMON asks users to provide sampling
interval and aggregation interval.  For the reason, there could be some
use case that using Idle Page Tracking is simpler.

2. Physical memory monitoring.

Idle Page Tracking receives PFN range as input, so natively supports
physical memory monitoring.

DAMON is designed to be extensible for multiple address spaces and use
cases by implementing and using primitives for the given use case.
Therefore, by theory, DAMON has no limitation in the type of target
address space as long as primitives for the given address space exists.
However, the default primitives introduced by this patchset supports only
virtual address spaces.

Therefore, for physical memory monitoring, you should implement your own
primitives and use it, or simply use Idle Page Tracking.

Nonetheless, RFC patchsets[1] for the physical memory address space
primitives is already available.  It also supports user memory same to
Idle Page Tracking.

[1] https://lore.kernel.org/linux-mm/20200831104730.28970-1-sjpark@amazon.com/

For what use cases DAMON is better?
-----------------------------------

1. Hotness Monitoring.

Idle Page Tracking let users know only if a page frame is accessed or not.
For hotness check, the user should write more code and use more memory.
DAMON do that by itself.

2. Low Monitoring Overhead

DAMON receives user's monitoring request with one step and then provide
the results.  So, roughly speaking, DAMON require only O(1) user/kernel
context switches.

In case of Idle Page Tracking, however, because the interface receives
contiguous page frames, the number of user/kernel context switches
increases as the monitoring target becomes complex and huge.  As a result,
the context switch overhead could be not negligible.

Moreover, DAMON is born to handle with the monitoring overhead.  Because
the core mechanism is pure logical, Idle Page Tracking users might be able
to implement the mechanism on their own, but it would be time consuming
and the user/kernel context switching will still more frequent than that
of DAMON.  Also, the kernel subsystems cannot use the logic in this case.

3. Page granularity working set size detection.

Until v22 of this patchset, this was categorized as the thing Idle Page
Tracking could do better, because DAMON basically maintains additional
metadata for each of the monitoring target regions.  So, in the page
granularity working set size detection use case, DAMON would incur (number
of monitoring target pages * size of metadata) memory overhead.  Size of
the single metadata item is about 54 bytes, so assuming 4KB pages, about
1.3% of monitoring target pages will be additionally used.

All essential metadata for Idle Page Tracking are embedded in 'struct
page' and page table entries.  Therefore, in this use case, only one
counter variable for working set size accounting is required if Idle Page
Tracking is used.

There are more details to consider, but roughly speaking, this is true in
most cases.

However, the situation changed from v23.  Now DAMON supports arbitrary
types of monitoring targets, which don't use the metadata.  Using that,
DAMON can do the working set size detection with no additional space
overhead but less user-kernel context switch.  A first draft for the
implementation of monitoring primitives for this usage is available in a
DAMON development tree[1].  An RFC patchset for it based on this patchset
will also be available soon.

Since v24, the arbitrary type support is dropped from this patchset
because this patchset doesn't introduce real use of the type.  You can
still get it from the DAMON development tree[2], though.

[1] https://github.com/sjp38/linux/tree/damon/pgidle_hack
[2] https://github.com/sjp38/linux/tree/damon/master

4. More future usecases

While Idle Page Tracking has tight coupling with base primitives (PG_Idle
and page table Accessed bits), DAMON is designed to be extensible for many
use cases and address spaces.  If you need some special address type or
want to use special h/w access check primitives, you can write your own
primitives for that and configure DAMON to use those.  Therefore, if your
use case could be changed a lot in future, using DAMON could be better.

Can I use both Idle Page Tracking and DAMON?
--------------------------------------------

Yes, though using them concurrently for overlapping memory regions could
result in interference to each other.  Nevertheless, such use case would
be rare or makes no sense at all.  Even in the case, the noise would bot
be really significant.  So, you can choose whatever you want depending on
the characteristics of your use cases.

More Information
================

We prepared a showcase web site[1] that you can get more information.
There are

- the official documentations[2],
- the heatmap format dynamic access pattern of various realistic workloads for
  heap area[3], mmap()-ed area[4], and stack[5] area,
- the dynamic working set size distribution[6] and chronological working set
  size changes[7], and
- the latest performance test results[8].

[1] https://damonitor.github.io/_index
[2] https://damonitor.github.io/doc/html/latest-damon
[3] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.0.png.html
[4] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
[5] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.2.png.html
[6] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
[7] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.png.html
[8] https://damonitor.github.io/test/result/perf/latest/html/index.html

Baseline and Complete Git Trees
===============================

The patches are based on the latest -mm tree, specifically
v5.14-rc1-mmots-2021-07-15-18-47 of https://github.com/hnaz/linux-mm.  You can
also clone the complete git tree:

    $ git clone git://github.com/sjp38/linux -b damon/patches/v34

The web is also available:
https://github.com/sjp38/linux/releases/tag/damon/patches/v34

Development Trees
-----------------

There are a couple of trees for entire DAMON patchset series and features
for future release.

- For latest release: https://github.com/sjp38/linux/tree/damon/master
- For next release: https://github.com/sjp38/linux/tree/damon/next

Long-term Support Trees
-----------------------

For people who want to test DAMON but using LTS kernels, there are another
couple of trees based on two latest LTS kernels respectively and
containing the 'damon/master' backports.

- For v5.4.y: https://github.com/sjp38/linux/tree/damon/for-v5.4.y
- For v5.10.y: https://github.com/sjp38/linux/tree/damon/for-v5.10.y

Amazon Linux Kernel Trees
-------------------------

DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].

[1] https://github.com/amazonlinux/linux/tree/amazon-5.4.y/master/mm/damon
[2] https://github.com/amazonlinux/linux/tree/amazon-5.10.y/master/mm/damon

Git Tree for Diff of Patches
============================

For easy review of diff between different versions of each patch, I
prepared a git tree containing all versions of the DAMON patchset series:
https://github.com/sjp38/damon-patches

You can clone it and use 'diff' for easy review of changes between
different versions of the patchset.  For example:

    $ git clone https://github.com/sjp38/damon-patches && cd damon-patches
    $ diff -u damon/v33 damon/v34

Sequence Of Patches
===================

First three patches implement the core logics of DAMON.  The 1st patch
introduces basic sampling based hotness monitoring for arbitrary types of
targets.  Following two patches implement the core mechanisms for control
of overhead and accuracy, namely regions based sampling (patch 2) and
adaptive regions adjustment (patch 3).

Now the essential parts of DAMON is complete, but it cannot work unless
someone provides monitoring primitives for a specific use case.  The
following two patches make it just work for virtual address spaces
monitoring.  The 4th patch makes 'PG_idle' can be used by DAMON and the
5th patch implements the virtual memory address space specific monitoring
primitives using page table Accessed bits and the 'PG_idle' page flag.

Now DAMON just works for virtual address space monitoring via the kernel
space api.  To let the user space users can use DAMON, following four
patches add interfaces for them.  The 6th patch adds a tracepoint for
monitoring results.  The 7th patch implements a DAMON application kernel
module, namely damon-dbgfs, that simply wraps DAMON and exposes DAMON
interface to the user space via the debugfs interface.  The 8th patch
further exports pid of monitoring thread (kdamond) to user space for
easier cpu usage accounting, and the 9th patch makes the debugfs interface
to support multiple contexts.

Three patches for maintainability follows.  The 10th patch adds
documentations for both the user space and the kernel space.  The 11th
patch provides unit tests (based on the kunit) while the 12th patch adds
user space tests (based on the kselftest).

Finally, the last patch (13th) updates the MAINTAINERS file.

This patch (of 13):

DAMON is a data access monitoring framework for the Linux kernel.  The
core mechanisms of DAMON make it

 - accurate (the monitoring output is useful enough for DRAM level
   performance-centric memory management; It might be inappropriate for
   CPU cache levels, though),
 - light-weight (the monitoring overhead is normally low enough to be
   applied online), and
 - scalable (the upper-bound of the overhead is in constant range
   regardless of the size of target workloads).

Using this framework, hence, we can easily write efficient kernel space
data access monitoring applications.  For example, the kernel's memory
management mechanisms can make advanced decisions using this.
Experimental data access aware optimization works that incurring high
access monitoring overhead could again be implemented on top of this.

Due to its simple and flexible interface, providing user space interface
would be also easy.  Then, user space users who have some special
workloads can write personalized applications for better understanding and
optimizations of their workloads and systems.

===

Nevertheless, this commit is defining and implementing only basic access
check part without the overhead-accuracy handling core logic.  The basic
access check is as below.

The output of DAMON says what memory regions are how frequently accessed
for a given duration.  The resolution of the access frequency is
controlled by setting ``sampling interval`` and ``aggregation interval``.
In detail, DAMON checks access to each page per ``sampling interval`` and
aggregates the results.  In other words, counts the number of the accesses
to each region.  After each ``aggregation interval`` passes, DAMON calls
callback functions that previously registered by users so that users can
read the aggregated results and then clears the results.  This can be
described in below simple pseudo-code::

    init()
    while monitoring_on:
        for page in monitoring_target:
            if accessed(page):
                nr_accesses[page] += 1
        if time() % aggregation_interval == 0:
            for callback in user_registered_callbacks:
                callback(monitoring_target, nr_accesses)
            for page in monitoring_target:
                nr_accesses[page] = 0
        if time() % update_interval == 0:
            update()
        sleep(sampling interval)

The target regions constructed at the beginning of the monitoring and
updated after each ``regions_update_interval``, because the target regions
could be dynamically changed (e.g., mmap() or memory hotplug).  The
monitoring overhead of this mechanism will arbitrarily increase as the
size of the target workload grows.

The basic monitoring primitives for actual access check and dynamic target
regions construction aren't in the core part of DAMON.  Instead, it allows
users to implement their own primitives that are optimized for their use
case and configure DAMON to use those.  In other words, users cannot use
current version of DAMON without some additional works.

Following commits will implement the core mechanisms for the
overhead-accuracy control and default primitives implementations.

Link: https://lkml.kernel.org/r/20210716081449.22187-1-sj38.park@gmail.com
Link: https://lkml.kernel.org/r/20210716081449.22187-2-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Leonard Foerster <foersleo@amazon.de>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Marco Elver <elver@google.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Joe Perches <joe@perches.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Markus Boehme <markubo@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-09-08 11:50:24 -07:00
Mike Rapoport
859a85ddf9 mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE 
Patch series "mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE".

After recent updates to freeing unused parts of the memory map, no
architecture can have holes in the memory map within a pageblock.  This
makes pfn_valid_within() check and CONFIG_HOLES_IN_ZONE configuration
option redundant.

The first patch removes them both in a mechanical way and the second patch
simplifies memory_hotplug::test_pages_in_a_zone() that had
pfn_valid_within() surrounded by more logic than simple if.

This patch (of 2):

After recent changes in freeing of the unused parts of the memory map and
rework of pfn_valid() in arm and arm64 there are no architectures that can
have holes in the memory map within a pageblock and so nothing can enable
CONFIG_HOLES_IN_ZONE which guards non trivial implementation of
pfn_valid_within().

With that, pfn_valid_within() is always hardwired to 1 and can be
completely removed.

Remove calls to pfn_valid_within() and CONFIG_HOLES_IN_ZONE.

Link: https://lkml.kernel.org/r/20210713080035.7464-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20210713080035.7464-2-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-09-08 11:50:22 -07:00
Mike Rapoport
1507f51255 mm: introduce memfd_secret system call to create "secret" memory areas 
Introduce "memfd_secret" system call with the ability to create memory
areas visible only in the context of the owning process and not mapped not
only to other processes but in the kernel page tables as well.

The secretmem feature is off by default and the user must explicitly
enable it at the boot time.

Once secretmem is enabled, the user will be able to create a file
descriptor using the memfd_secret() system call.  The memory areas created
by mmap() calls from this file descriptor will be unmapped from the kernel
direct map and they will be only mapped in the page table of the processes
that have access to the file descriptor.

Secretmem is designed to provide the following protections:

* Enhanced protection (in conjunction with all the other in-kernel
  attack prevention systems) against ROP attacks.  Seceretmem makes
  "simple" ROP insufficient to perform exfiltration, which increases the
  required complexity of the attack.  Along with other protections like
  the kernel stack size limit and address space layout randomization which
  make finding gadgets is really hard, absence of any in-kernel primitive
  for accessing secret memory means the one gadget ROP attack can't work.
  Since the only way to access secret memory is to reconstruct the missing
  mapping entry, the attacker has to recover the physical page and insert
  a PTE pointing to it in the kernel and then retrieve the contents.  That
  takes at least three gadgets which is a level of difficulty beyond most
  standard attacks.

* Prevent cross-process secret userspace memory exposures.  Once the
  secret memory is allocated, the user can't accidentally pass it into the
  kernel to be transmitted somewhere.  The secreremem pages cannot be
  accessed via the direct map and they are disallowed in GUP.

* Harden against exploited kernel flaws.  In order to access secretmem,
  a kernel-side attack would need to either walk the page tables and
  create new ones, or spawn a new privileged uiserspace process to perform
  secrets exfiltration using ptrace.

The file descriptor based memory has several advantages over the
"traditional" mm interfaces, such as mlock(), mprotect(), madvise().  File
descriptor approach allows explicit and controlled sharing of the memory
areas, it allows to seal the operations.  Besides, file descriptor based
memory paves the way for VMMs to remove the secret memory range from the
userspace hipervisor process, for instance QEMU.  Andy Lutomirski says:

  "Getting fd-backed memory into a guest will take some possibly major
  work in the kernel, but getting vma-backed memory into a guest without
  mapping it in the host user address space seems much, much worse."

memfd_secret() is made a dedicated system call rather than an extension to
memfd_create() because it's purpose is to allow the user to create more
secure memory mappings rather than to simply allow file based access to
the memory.  Nowadays a new system call cost is negligible while it is way
simpler for userspace to deal with a clear-cut system calls than with a
multiplexer or an overloaded syscall.  Moreover, the initial
implementation of memfd_secret() is completely distinct from
memfd_create() so there is no much sense in overloading memfd_create() to
begin with.  If there will be a need for code sharing between these
implementation it can be easily achieved without a need to adjust user
visible APIs.

The secret memory remains accessible in the process context using uaccess
primitives, but it is not exposed to the kernel otherwise; secret memory
areas are removed from the direct map and functions in the
follow_page()/get_user_page() family will refuse to return a page that
belongs to the secret memory area.

Once there will be a use case that will require exposing secretmem to the
kernel it will be an opt-in request in the system call flags so that user
would have to decide what data can be exposed to the kernel.

Removing of the pages from the direct map may cause its fragmentation on
architectures that use large pages to map the physical memory which
affects the system performance.  However, the original Kconfig text for
CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct map "...  can
improve the kernel's performance a tiny bit ..." (commit 00d1c5e057
("x86: add gbpages switches")) and the recent report [1] showed that "...
although 1G mappings are a good default choice, there is no compelling
evidence that it must be the only choice".  Hence, it is sufficient to
have secretmem disabled by default with the ability of a system
administrator to enable it at boot time.

Pages in the secretmem regions are unevictable and unmovable to avoid
accidental exposure of the sensitive data via swap or during page
migration.

Since the secretmem mappings are locked in memory they cannot exceed
RLIMIT_MEMLOCK.  Since these mappings are already locked independently
from mlock(), an attempt to mlock()/munlock() secretmem range would fail
and mlockall()/munlockall() will ignore secretmem mappings.

However, unlike mlock()ed memory, secretmem currently behaves more like
long-term GUP: secretmem mappings are unmovable mappings directly consumed
by user space.  With default limits, there is no excessive use of
secretmem and it poses no real problem in combination with
ZONE_MOVABLE/CMA, but in the future this should be addressed to allow
balanced use of large amounts of secretmem along with ZONE_MOVABLE/CMA.

A page that was a part of the secret memory area is cleared when it is
freed to ensure the data is not exposed to the next user of that page.

The following example demonstrates creation of a secret mapping (error
handling is omitted):

	fd = memfd_secret(0);
	ftruncate(fd, MAP_SIZE);
	ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
		   MAP_SHARED, fd, 0);

[1] https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux.intel.com/

[akpm@linux-foundation.org: suppress Kconfig whine]

Link: https://lkml.kernel.org/r/20210518072034.31572-5-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Hagen Paul Pfeifer <hagen@jauu.net>
Acked-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-07-08 11:48:21 -07:00
Kefeng Wang
63703f37aa mm: generalize ZONE_[DMA|DMA32] 
ZONE_[DMA|DMA32] configs have duplicate definitions on platforms that
subscribe to them.  Instead, just make them generic options which can be
selected on applicable platforms.

Also only x86/arm64 architectures could enable both ZONE_DMA and
ZONE_DMA32 if EXPERT, add ARCH_HAS_ZONE_DMA_SET to make dma zone
configurable and visible on the two architectures.

Link: https://lkml.kernel.org/r/20210528074557.17768-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>	[m68k]
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>	[RISC-V]
Acked-by: Michal Simek <michal.simek@xilinx.com>	[microblaze]
Acked-by: Michael Ellerman <mpe@ellerman.id.au>		[powerpc]
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-06-30 20:47:30 -07:00
Miaohe Lin
2a03085ce8 mm/zbud: don't export any zbud API 
The zbud doesn't need to export any API and it is meant to be used via
zpool API since the commit 12d79d64bf ("mm/zpool: update zswap to use
zpool").  So we can remove the unneeded zbud.h and move down zpool API to
avoid any forward declaration.

[linmiaohe@huawei.com: fix unused function warnings when CONFIG_ZPOOL is disabled]
  Link: https://lkml.kernel.org/r/20210619025508.1239386-1-linmiaohe@huawei.com

Link: https://lkml.kernel.org/r/20210608114515.206992-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-06-30 20:47:29 -07:00
Kefeng Wang
781eb2cdd2 mm/kconfig: move HOLES_IN_ZONE into mm 
commit a55749639dc1 ("ia64: drop marked broken DISCONTIGMEM and
VIRTUAL_MEM_MAP") drop VIRTUAL_MEM_MAP, so there is no need HOLES_IN_ZONE
on ia64.

Also move HOLES_IN_ZONE into mm/Kconfig, select it if architecture needs
this feature.

Link: https://lkml.kernel.org/r/20210417075946.181402-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-06-30 20:47:28 -07:00
Mike Rapoport
43b02ba93b mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM 
After removal of the DISCONTIGMEM memory model the FLAT_NODE_MEM_MAP
configuration option is equivalent to FLATMEM.

Drop CONFIG_FLAT_NODE_MEM_MAP and use CONFIG_FLATMEM instead.

Link: https://lkml.kernel.org/r/20210608091316.3622-10-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-06-29 10:53:55 -07:00
Mike Rapoport
a9ee6cf5c6 mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA 
After removal of DISCINTIGMEM the NEED_MULTIPLE_NODES and NUMA
configuration options are equivalent.

Drop CONFIG_NEED_MULTIPLE_NODES and use CONFIG_NUMA instead.

Done with

	$ sed -i 's/CONFIG_NEED_MULTIPLE_NODES/CONFIG_NUMA/' \
		$(git grep -wl CONFIG_NEED_MULTIPLE_NODES)
	$ sed -i 's/NEED_MULTIPLE_NODES/NUMA/' \
		$(git grep -wl NEED_MULTIPLE_NODES)

with manual tweaks afterwards.

[rppt@linux.ibm.com: fix arm boot crash]
  Link: https://lkml.kernel.org/r/YMj9vHhHOiCVN4BF@linux.ibm.com

Link: https://lkml.kernel.org/r/20210608091316.3622-9-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-06-29 10:53:55 -07:00
Mike Rapoport
bb1c50d396 mm: remove CONFIG_DISCONTIGMEM 
There are no architectures that support DISCONTIGMEM left.

Remove the configuration option and the dead code it was guarding in the
generic memory management code.

Link: https://lkml.kernel.org/r/20210608091316.3622-6-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-06-29 10:53:55 -07:00
Oscar Salvador
a08a2ae346 mm,memory_hotplug: allocate memmap from the added memory range 
Physical memory hotadd has to allocate a memmap (struct page array) for
the newly added memory section.  Currently, alloc_pages_node() is used
for those allocations.

This has some disadvantages:
 a) an existing memory is consumed for that purpose
    (eg: ~2MB per 128MB memory section on x86_64)
    This can even lead to extreme cases where system goes OOM because
    the physically hotplugged memory depletes the available memory before
    it is onlined.
 b) if the whole node is movable then we have off-node struct pages
    which has performance drawbacks.
 c) It might be there are no PMD_ALIGNED chunks so memmap array gets
    populated with base pages.

This can be improved when CONFIG_SPARSEMEM_VMEMMAP is enabled.

Vmemap page tables can map arbitrary memory.  That means that we can
reserve a part of the physically hotadded memory to back vmemmap page
tables.  This implementation uses the beginning of the hotplugged memory
for that purpose.

There are some non-obviously things to consider though.

Vmemmap pages are allocated/freed during the memory hotplug events
(add_memory_resource(), try_remove_memory()) when the memory is
added/removed.  This means that the reserved physical range is not
online although it is used.  The most obvious side effect is that
pfn_to_online_page() returns NULL for those pfns.  The current design
expects that this should be OK as the hotplugged memory is considered a
garbage until it is onlined.  For example hibernation wouldn't save the
content of those vmmemmaps into the image so it wouldn't be restored on
resume but this should be OK as there no real content to recover anyway
while metadata is reachable from other data structures (e.g.  vmemmap
page tables).

The reserved space is therefore (de)initialized during the {on,off}line
events (mhp_{de}init_memmap_on_memory).  That is done by extracting page
allocator independent initialization from the regular onlining path.
The primary reason to handle the reserved space outside of
{on,off}line_pages is to make each initialization specific to the
purpose rather than special case them in a single function.

As per above, the functions that are introduced are:

 - mhp_init_memmap_on_memory:
   Initializes vmemmap pages by calling move_pfn_range_to_zone(), calls
   kasan_add_zero_shadow(), and onlines as many sections as vmemmap pages
   fully span.

 - mhp_deinit_memmap_on_memory:
   Offlines as many sections as vmemmap pages fully span, removes the
   range from zhe zone by remove_pfn_range_from_zone(), and calls
   kasan_remove_zero_shadow() for the range.

The new function memory_block_online() calls mhp_init_memmap_on_memory()
before doing the actual online_pages().  Should online_pages() fail, we
clean up by calling mhp_deinit_memmap_on_memory().  Adjusting of
present_pages is done at the end once we know that online_pages()
succedeed.

On offline, memory_block_offline() needs to unaccount vmemmap pages from
present_pages() before calling offline_pages().  This is necessary because
offline_pages() tears down some structures based on the fact whether the
node or the zone become empty.  If offline_pages() fails, we account back
vmemmap pages.  If it succeeds, we call mhp_deinit_memmap_on_memory().

Hot-remove:

 We need to be careful when removing memory, as adding and
 removing memory needs to be done with the same granularity.
 To check that this assumption is not violated, we check the
 memory range we want to remove and if a) any memory block has
 vmemmap pages and b) the range spans more than a single memory
 block, we scream out loud and refuse to proceed.

 If all is good and the range was using memmap on memory (aka vmemmap pages),
 we construct an altmap structure so free_hugepage_table does the right
 thing and calls vmem_altmap_free instead of free_pagetable.

Link: https://lkml.kernel.org/r/20210421102701.25051-5-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-05-05 11:27:26 -07:00
Anshuman Khandual
91024b3ce2 mm: generalize ARCH_ENABLE_MEMORY_[HOTPLUG|HOTREMOVE] 
ARCH_ENABLE_MEMORY_[HOTPLUG|HOTREMOVE] configs have duplicate
definitions on platforms that subscribe them.  Instead, just make them
generic options which can be selected on applicable platforms.

Link: https://lkml.kernel.org/r/1617259448-22529-4-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Acked-by: Heiko Carstens <hca@linux.ibm.com>		[s390]
Cc: Will Deacon <will@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-05-05 11:27:25 -07:00
Anshuman Khandual
c2280be81d mm: generalize ARCH_HAS_CACHE_LINE_SIZE 
Patch series "mm: some config cleanups", v2.

This series contains config cleanup patches which reduces code
duplication across platforms and also improves maintainability.  There
is no functional change intended with this series.

This patch (of 6):

ARCH_HAS_CACHE_LINE_SIZE config has duplicate definitions on platforms
that subscribe it.  Instead, just make it a generic option which can be
selected on applicable platforms.  This change reduces code duplication
and makes it cleaner.

Link: https://lkml.kernel.org/r/1617259448-22529-1-git-send-email-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/1617259448-22529-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Acked-by: Vineet Gupta <vgupta@synopsys.com>		[arc]
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-05-05 11:27:25 -07:00
Minchan Kim
43ca106fa8 mm: cma: support sysfs 
Since CMA is getting used more widely, it's more important to keep
monitoring CMA statistics for system health since it's directly related to
user experience.

This patch introduces sysfs statistics for CMA, in order to provide some
basic monitoring of the CMA allocator.

 * the number of CMA page successful allocations
 * the number of CMA page allocation failures

These two values allow the user to calcuate the allocation
failure rate for each CMA area.

e.g.)
  /sys/kernel/mm/cma/WIFI/alloc_pages_[success|fail]
  /sys/kernel/mm/cma/SENSOR/alloc_pages_[success|fail]
  /sys/kernel/mm/cma/BLUETOOTH/alloc_pages_[success|fail]

The cma_stat was intentionally allocated by dynamic allocation
to harmonize with kobject lifetime management.
https://lore.kernel.org/linux-mm/YCOAmXqt6dZkCQYs@kroah.com/

Link: https://lkml.kernel.org/r/20210324230759.2213957-1-minchan@kernel.org
Link: https://lore.kernel.org/linux-mm/20210316100433.17665-1-colin.king@canonical.com/
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>

Tested-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: John Dias <joaodias@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-05-05 11:27:24 -07:00
Anshuman Khandual
4bfb68a085 mm: generalize HUGETLB_PAGE_SIZE_VARIABLE 
HUGETLB_PAGE_SIZE_VARIABLE need not be defined for each individual
platform subscribing it.  Instead just make it generic.

Link: https://lkml.kernel.org/r/1614914928-22039-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>	[powerpc]
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-05-05 11:27:20 -07:00
Geert Uytterhoeven
d68d015a7e mm/Kconfig: remove default DISCONTIGMEM_MANUAL 
Commit 214496cb18 ("ia64: make SPARSEMEM default and disable
DISCONTIGMEM") removed the last enabler of ARCH_DISCONTIGMEM_DEFAULT,
hence the memory model can no longer default to DISCONTIGMEM_MANUAL.

Link: https://lkml.kernel.org/r/20210312141208.3465520-1-geert@linux-m68k.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-04-30 11:20:43 -07:00
Christoph Hellwig
1fbaf8fc12 mm: add a io_mapping_map_user helper 
Add a helper that calls remap_pfn_range for an struct io_mapping, relying
on the pgprot pre-validation done when creating the mapping instead of
doing it at runtime.

Link: https://lkml.kernel.org/r/20210326055505.1424432-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2021-04-30 11:20:39 -07:00
Christoph Hellwig
ce288e0535 block: remove BLK_BOUNCE_ISA support 
Remove the BLK_BOUNCE_ISA support now that all users are gone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210331073001.46776-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
 2021-04-06 09:28:17 -06:00
Daniel Vetter
eb83b8e3e6 media: videobuf2: Move frame_vector into media subsystem 
It's the only user. This also garbage collects the CONFIG_FRAME_VECTOR
symbol from all over the tree (well just one place, somehow omap media
driver still had this in its Kconfig, despite not using it).

Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Pawel Osciak <pawel@osciak.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-7-daniel.vetter@ffwll.ch
 2021-01-12 14:15:31 +01:00
Colin Ian King
01ab1ede91 mm/Kconfig: fix spelling mistake "whats" -> "what's" 
There is a spelling mistake in the Kconfig help text. Fix it.

Link: https://lkml.kernel.org/r/20201217172717.58203-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-12-19 11:25:41 -08:00
Linus Torvalds
5ee863bec7 Merge branch 'parisc-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 
Pull parisc updates from Helge Deller:
 "A change to increase the default maximum stack size on parisc to 100MB
  and the ability to further increase the stack hard limit size at
  runtime with ulimit for newly started processes.

  The other patches fix compile warnings, utilize the Kbuild logic and
  cleanups the parisc arch code"

* 'parisc-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: pci-dma: fix warning unused-function
  parisc/uapi: Use Kbuild logic to provide <asm/types.h>
  parisc: Make user stack size configurable
  parisc: Use _TIF_USER_WORK_MASK in entry.S
  parisc: Drop loops_per_jiffy from per_cpu struct
 2020-12-16 12:10:40 -08:00
Linus Torvalds
ac73e3dc8a Merge branch 'akpm' (patches from Andrew) 
Merge misc updates from Andrew Morton:

 - a few random little subsystems

 - almost all of the MM patches which are staged ahead of linux-next
   material. I'll trickle to post-linux-next work in as the dependents
   get merged up.

Subsystems affected by this patch series: kthread, kbuild, ide, ntfs,
ocfs2, arch, and mm (slab-generic, slab, slub, dax, debug, pagecache,
gup, swap, shmem, memcg, pagemap, mremap, hmm, vmalloc, documentation,
kasan, pagealloc, memory-failure, hugetlb, vmscan, z3fold, compaction,
oom-kill, migration, cma, page-poison, userfaultfd, zswap, zsmalloc,
uaccess, zram, and cleanups).

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (200 commits)
  mm: cleanup kstrto*() usage
  mm: fix fall-through warnings for Clang
  mm: slub: convert sysfs sprintf family to sysfs_emit/sysfs_emit_at
  mm: shmem: convert shmem_enabled_show to use sysfs_emit_at
  mm:backing-dev: use sysfs_emit in macro defining functions
  mm: huge_memory: convert remaining use of sprintf to sysfs_emit and neatening
  mm: use sysfs_emit for struct kobject * uses
  mm: fix kernel-doc markups
  zram: break the strict dependency from lzo
  zram: add stat to gather incompressible pages since zram set up
  zram: support page writeback
  mm/process_vm_access: remove redundant initialization of iov_r
  mm/zsmalloc.c: rework the list_add code in insert_zspage()
  mm/zswap: move to use crypto_acomp API for hardware acceleration
  mm/zswap: fix passing zero to 'PTR_ERR' warning
  mm/zswap: make struct kernel_param_ops definitions const
  userfaultfd/selftests: hint the test runner on required privilege
  userfaultfd/selftests: fix retval check for userfaultfd_open()
  userfaultfd/selftests: always dump something in modes
  userfaultfd: selftests: make __{s,u}64 format specifiers portable
  ...
 2020-12-15 12:53:37 -08:00
Barry Song
d0de824118 mm/gup_test: GUP_TEST depends on DEBUG_FS 
Without DEBUG_FS, all the code in gup_benchmark becomes meaningless.
For sure kernel provides debugfs stub while DEBUG_FS is disabled, but
the point here is that GUP_TEST can do nothing without DEBUG_FS.

[song.bao.hua@hisilicon.com: add comment as a prompt to users as commented by John and Randy]
  Link: https://lkml.kernel.org/r/20201108083732.15336-1-song.bao.hua@hisilicon.com

Link: https://lkml.kernel.org/r/20201104100552.20156-1-song.bao.hua@hisilicon.com
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Suggested-by: John Garry <john.garry@huawei.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-12-15 12:13:38 -08:00
John Hubbard
f4f9bda418 selftests/vm: gup_test: introduce the dump_pages() sub-test 
For quite a while, I was doing a quick hack to gup_test.c (previously,
gup_benchmark.c) whenever I wanted to try out my changes to dump_page().
This makes that hack unnecessary, and instead allows anyone to easily get
the same coverage from a user space program.  That saves a lot of time
because you don't have to change the kernel, in order to test different
pages and options.

The new sub-test takes advantage of the existing gup_test infrastructure,
which already provides a simple user space program, some allocated user
space pages, an ioctl call, pinning of those pages (via either
get_user_pages or pin_user_pages) and a corresponding kernel-side test
invocation.  There's not much more required, mainly just a couple of
inputs from the user.

In fact, the new test re-uses the existing command line options in order
to get various helpful combinations (THP or normal, _fast or slow gup, gup
vs.  pup, and more).

New command line options are: which pages to dump, and what type of
"get/pin" to use.

In order to figure out which pages to dump, the logic is:

* If the user doesn't specify anything, the page 0 (the first page in
  the address range that the program sets up for testing) is dumped.

* Or, the user can type up to 8 page indices anywhere on the command
  line.  If you type more than 8, then it uses the first 8 and ignores the
  remaining items.

For example:

    ./gup_test -ct -F 1 0 19 0x1000

Meaning:
    -c:          dump pages sub-test
    -t:          use THP pages
    -F 1:        use pin_user_pages() instead of get_user_pages()
    0 19 0x1000: dump pages 0, 19, and 4096

Link: https://lkml.kernel.org/r/20201026064021.3545418-7-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-12-15 12:13:38 -08:00
John Hubbard
9c84f22926 mm/gup_benchmark: rename to mm/gup_test 
Patch series "selftests/vm: gup_test, hmm-tests, assorted improvements", v3.

Summary: This series provides two main things, and a number of smaller
supporting goodies.  The two main points are:

1) Add a new sub-test to gup_test, which in turn is a renamed version
   of gup_benchmark.  This sub-test allows nicer testing of dump_pages(),
   at least on user-space pages.

   For quite a while, I was doing a quick hack to gup_test.c whenever I
   wanted to try out changes to dump_page().  Then Matthew Wilcox asked me
   what I meant when I said "I used my dump_page() unit test", and I
   realized that it might be nice to check in a polished up version of
   that.

   Details about how it works and how to use it are in the commit
   description for patch #6 ("selftests/vm: gup_test: introduce the
   dump_pages() sub-test").

2) Fixes a limitation of hmm-tests: these tests are incredibly useful,
   but only if people actually build and run them.  And it turns out that
   libhugetlbfs is a little too effective at throwing a wrench in the
   works, there.  So I've added a little configuration check that removes
   just two of the 21 hmm-tests, if libhugetlbfs is not available.

   Further details in the commit description of patch #8
   ("selftests/vm: hmm-tests: remove the libhugetlbfs dependency").

Other smaller things that this series does:

a) Remove code duplication by creating gup_test.h.

b) Clear up the sub-test organization, and their invocation within
   run_vmtests.sh.

c) Other minor assorted improvements.

[1] v2 is here:
https://lore.kernel.org/linux-doc/20200929212747.251804-1-jhubbard@nvidia.com/

[2] https://lore.kernel.org/r/CAHk-=wgh-TMPHLY3jueHX7Y2fWh3D+nMBqVS__AZm6-oorquWA@mail.gmail.com

This patch (of 9):

Rename nearly every "gup_benchmark" reference and file name to "gup_test".
The one exception is for the actual gup benchmark test itself.

The current code already does a *little* bit more than benchmarking, and
definitely covers more than get_user_pages_fast().  More importantly,
however, subsequent patches are about to add some functionality that is
non-benchmark related.

Closely related changes:

* Kconfig: in addition to renaming the options from GUP_BENCHMARK to
  GUP_TEST, update the help text to reflect that it's no longer a
  benchmark-only test.

Link: https://lkml.kernel.org/r/20201026064021.3545418-1-jhubbard@nvidia.com
Link: https://lkml.kernel.org/r/20201026064021.3545418-2-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-12-15 12:13:38 -08:00
Linus Torvalds
edd7ab7684 The new preemtible kmap_local() implementation: 
- Consolidate all kmap_atomic() internals into a generic implementation
     which builds the base for the kmap_local() API and make the
     kmap_atomic() interface wrappers which handle the disabling/enabling of
     preemption and pagefaults.
 
   - Switch the storage from per-CPU to per task and provide scheduler
     support for clearing mapping when scheduling out and restoring them
     when scheduling back in.
 
   - Merge the migrate_disable/enable() code, which is also part of the
     scheduler pull request. This was required to make the kmap_local()
     interface available which does not disable preemption when a mapping
     is established. It has to disable migration instead to guarantee that
     the virtual address of the mapped slot is the same accross preemption.
 
   - Provide better debug facilities: guard pages and enforced utilization
     of the mapping mechanics on 64bit systems when the architecture allows
     it.
 
   - Provide the new kmap_local() API which can now be used to cleanup the
     kmap_atomic() usage sites all over the place. Most of the usage sites
     do not require the implicit disabling of preemption and pagefaults so
     the penalty on 64bit and 32bit non-highmem systems is removed and quite
     some of the code can be simplified. A wholesale conversion is not
     possible because some usage depends on the implicit side effects and
     some need to be cleaned up because they work around these side effects.
 
     The migrate disable side effect is only effective on highmem systems
     and when enforced debugging is enabled. On 64bit and 32bit non-highmem
     systems the overhead is completely avoided.
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Merge tag 'core-mm-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull kmap updates from Thomas Gleixner:
 "The new preemtible kmap_local() implementation:

   - Consolidate all kmap_atomic() internals into a generic
     implementation which builds the base for the kmap_local() API and
     make the kmap_atomic() interface wrappers which handle the
     disabling/enabling of preemption and pagefaults.

   - Switch the storage from per-CPU to per task and provide scheduler
     support for clearing mapping when scheduling out and restoring them
     when scheduling back in.

   - Merge the migrate_disable/enable() code, which is also part of the
     scheduler pull request. This was required to make the kmap_local()
     interface available which does not disable preemption when a
     mapping is established. It has to disable migration instead to
     guarantee that the virtual address of the mapped slot is the same
     across preemption.

   - Provide better debug facilities: guard pages and enforced
     utilization of the mapping mechanics on 64bit systems when the
     architecture allows it.

   - Provide the new kmap_local() API which can now be used to cleanup
     the kmap_atomic() usage sites all over the place. Most of the usage
     sites do not require the implicit disabling of preemption and
     pagefaults so the penalty on 64bit and 32bit non-highmem systems is
     removed and quite some of the code can be simplified. A wholesale
     conversion is not possible because some usage depends on the
     implicit side effects and some need to be cleaned up because they
     work around these side effects.

     The migrate disable side effect is only effective on highmem
     systems and when enforced debugging is enabled. On 64bit and 32bit
     non-highmem systems the overhead is completely avoided"

* tag 'core-mm-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  ARM: highmem: Fix cache_is_vivt() reference
  x86/crashdump/32: Simplify copy_oldmem_page()
  io-mapping: Provide iomap_local variant
  mm/highmem: Provide kmap_local*
  sched: highmem: Store local kmaps in task struct
  x86: Support kmap_local() forced debugging
  mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP
  mm/highmem: Provide and use CONFIG_DEBUG_KMAP_LOCAL
  microblaze/mm/highmem: Add dropped #ifdef back
  xtensa/mm/highmem: Make generic kmap_atomic() work correctly
  mm/highmem: Take kmap_high_get() properly into account
  highmem: High implementation details and document API
  Documentation/io-mapping: Remove outdated blurb
  io-mapping: Cleanup atomic iomap
  mm/highmem: Remove the old kmap_atomic cruft
  highmem: Get rid of kmap_types.h
  xtensa/mm/highmem: Switch to generic kmap atomic
  sparc/mm/highmem: Switch to generic kmap atomic
  powerpc/mm/highmem: Switch to generic kmap atomic
  nds32/mm/highmem: Switch to generic kmap atomic
  ...
 2020-12-14 18:35:53 -08:00
Minchan Kim
e91d8d7823 mm/zsmalloc.c: drop ZSMALLOC_PGTABLE_MAPPING 
While I was doing zram testing, I found sometimes decompression failed
since the compression buffer was corrupted.  With investigation, I found
below commit calls cond_resched unconditionally so it could make a
problem in atomic context if the task is reschedule.

  BUG: sleeping function called from invalid context at mm/vmalloc.c:108
  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 946, name: memhog
  3 locks held by memhog/946:
   #0: ffff9d01d4b193e8 (&mm->mmap_lock#2){++++}-{4:4}, at: __mm_populate+0x103/0x160
   #1: ffffffffa3d53de0 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_slowpath.constprop.0+0xa98/0x1160
   #2: ffff9d01d56b8110 (&zspage->lock){.+.+}-{3:3}, at: zs_map_object+0x8e/0x1f0
  CPU: 0 PID: 946 Comm: memhog Not tainted 5.9.3-00011-gc5bfc0287345-dirty #316
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014
  Call Trace:
    unmap_kernel_range_noflush+0x2eb/0x350
    unmap_kernel_range+0x14/0x30
    zs_unmap_object+0xd5/0xe0
    zram_bvec_rw.isra.0+0x38c/0x8e0
    zram_rw_page+0x90/0x101
    bdev_write_page+0x92/0xe0
    __swap_writepage+0x94/0x4a0
    pageout+0xe3/0x3a0
    shrink_page_list+0xb94/0xd60
    shrink_inactive_list+0x158/0x460

We can fix this by removing the ZSMALLOC_PGTABLE_MAPPING feature (which
contains the offending calling code) from zsmalloc.

Even though this option showed some amount improvement(e.g., 30%) in
some arm32 platforms, it has been headache to maintain since it have
abused APIs[1](e.g., unmap_kernel_range in atomic context).

Since we are approaching to deprecate 32bit machines and already made
the config option available for only builtin build since v5.8, lastly it
has been not default option in zsmalloc, it's time to drop the option
for better maintenance.

[1] http://lore.kernel.org/linux-mm/20201105170249.387069-1-minchan@kernel.org

Fixes: e47110e905 ("mm/vunmap: add cond_resched() in vunmap_pmd_range")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Harish Sriram <harish@linux.ibm.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201117202916.GA3856507@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-12-06 10:19:07 -08:00