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Mike Kravetz 0ef7dcac99 mm/cma: change cma mutex to irq safe spinlock
Patch series "make hugetlb put_page safe for all calling contexts", v5.

This effort is the result a recent bug report [1].  Syzbot found a
potential deadlock in the hugetlb put_page/free_huge_page_path.  WARNING:
SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected Since the
free_huge_page_path already has code to 'hand off' page free requests to a
workqueue, a suggestion was proposed to make the in_irq() detection
accurate by always enabling PREEMPT_COUNT [2].  The outcome of that
discussion was that the hugetlb put_page path (free_huge_page) path should
be properly fixed and safe for all calling contexts.

[1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/
[2] http://lkml.kernel.org/r/20210311021321.127500-1-mike.kravetz@oracle.com

This patch (of 8):

cma_release is currently a sleepable operatation because the bitmap
manipulation is protected by cma->lock mutex.  Hugetlb code which relies
on cma_release for CMA backed (giga) hugetlb pages, however, needs to be
irq safe.

The lock doesn't protect any sleepable operation so it can be changed to a
(irq aware) spin lock.  The bitmap processing should be quite fast in
typical case but if cma sizes grow to TB then we will likely need to
replace the lock by a more optimized bitmap implementation.

Link: https://lkml.kernel.org/r/20210409205254.242291-1-mike.kravetz@oracle.com
Link: https://lkml.kernel.org/r/20210409205254.242291-2-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 11:27:21 -07:00
arch mm: generalize HUGETLB_PAGE_SIZE_VARIABLE 2021-05-05 11:27:20 -07:00
block cgroup: rstat: punt root-level optimization to individual controllers 2021-04-30 11:20:37 -07:00
certs certs: add 'x509_revocation_list' to gitignore 2021-04-26 10:48:07 -07:00
crypto for-5.13/drivers-2021-04-27 2021-04-28 14:39:37 -07:00
Documentation mm/mmzone.h: fix existing kernel-doc comments and link them to core-api 2021-04-30 11:20:43 -07:00
drivers mm/vmalloc: remove unmap_kernel_range 2021-04-30 11:20:40 -07:00
fs mm/hugetlb: remove unused variable pseudo_vma in remove_inode_hugepages() 2021-05-05 11:27:21 -07:00
include mm/huge_memory.c: remove unused macro TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG 2021-05-05 11:27:21 -07:00
init mm: move mem_init_print_info() into mm_init() 2021-04-30 11:20:42 -07:00
ipc fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
kernel irq_work: record irq_work_queue() call stack 2021-04-30 11:20:42 -07:00
lib kasan: detect false-positives in tests 2021-04-30 11:20:42 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm/cma: change cma mutex to irq safe spinlock 2021-05-05 11:27:21 -07:00
net net: page_pool: use alloc_pages_bulk in refill code path 2021-04-30 11:20:43 -07:00
samples samples/vfio-mdev/mdpy: use remap_vmalloc_range 2021-04-30 11:20:39 -07:00
scripts scripts: a new script for checking duplicate struct declaration 2021-04-30 11:20:35 -07:00
security Networking changes for 5.13. 2021-04-29 11:57:23 -07:00
sound - Core Frameworks 2021-04-28 15:59:13 -07:00
tools mm: huge_memory: debugfs for file-backed THP split 2021-05-05 11:27:21 -07:00
usr Kbuild updates for v5.12 2021-02-25 10:17:31 -08:00
virt KVM: x86/mmu: Consider the hva in mmu_notifier retry 2021-02-22 13:16:53 -05:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-04-25 05:17:02 +09:00
.mailmap It's been a relatively busy cycle in docsland, though more than usually 2021-04-26 13:22:43 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Core Frameworks 2021-04-28 15:59:13 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: assign pagewalk.h to MEMORY MANAGEMENT 2021-04-30 11:20:41 -07:00
Makefile Kconfig updates for v5.13 2021-04-29 14:32:00 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.