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linux-next/mm
David Hildenbrand 322842ea3c mm/rmap: fix missing swap_free() in try_to_unmap() after arch_unmap_one() failed
Patch series "mm: COW fixes part 2: reliable GUP pins of anonymous pages", v4.

This series is the result of the discussion on the previous approach [2]. 
More information on the general COW issues can be found there.  It is
based on latest linus/master (post v5.17, with relevant core-MM changes
for v5.18-rc1).

This series fixes memory corruptions when a GUP pin (FOLL_PIN) was taken
on an anonymous page and COW logic fails to detect exclusivity of the page
to then replacing the anonymous page by a copy in the page table: The GUP
pin lost synchronicity with the pages mapped into the page tables.

This issue, including other related COW issues, has been summarized in [3]
under 3):
"
  3. Intra Process Memory Corruptions due to Wrong COW (FOLL_PIN)

  page_maybe_dma_pinned() is used to check if a page may be pinned for
  DMA (using FOLL_PIN instead of FOLL_GET).  While false positives are
  tolerable, false negatives are problematic: pages that are pinned for
  DMA must not be added to the swapcache.  If it happens, the (now pinned)
  page could be faulted back from the swapcache into page tables
  read-only.  Future write-access would detect the pinning and COW the
  page, losing synchronicity.  For the interested reader, this is nicely
  documented in feb889fb40 ("mm: don't put pinned pages into the swap
  cache").

  Peter reports [8] that page_maybe_dma_pinned() as used is racy in some
  cases and can result in a violation of the documented semantics: giving
  false negatives because of the race.

  There are cases where we call it without properly taking a per-process
  sequence lock, turning the usage of page_maybe_dma_pinned() racy.  While
  one case (clear_refs SOFTDIRTY tracking, see below) seems to be easy to
  handle, there is especially one rmap case (shrink_page_list) that's hard
  to fix: in the rmap world, we're not limited to a single process.

  The shrink_page_list() issue is really subtle.  If we race with
  someone pinning a page, we can trigger the same issue as in the FOLL_GET
  case.  See the detail section at the end of this mail on a discussion
  how bad this can bite us with VFIO or other FOLL_PIN user.

  It's harder to reproduce, but I managed to modify the O_DIRECT
  reproducer to use io_uring fixed buffers [15] instead, which ends up
  using FOLL_PIN | FOLL_WRITE | FOLL_LONGTERM to pin buffer pages and can
  similarly trigger a loss of synchronicity and consequently a memory
  corruption.

  Again, the root issue is that a write-fault on a page that has
  additional references results in a COW and thereby a loss of
  synchronicity and consequently a memory corruption if two parties
  believe they are referencing the same page.
"

This series makes GUP pins (R/O and R/W) on anonymous pages fully
reliable, especially also taking care of concurrent pinning via GUP-fast,
for example, also fully fixing an issue reported regarding NUMA balancing
[4] recently.  While doing that, it further reduces "unnecessary COWs",
especially when we don't fork()/KSM and don't swapout, and fixes the COW
security for hugetlb for FOLL_PIN.

In summary, we track via a pageflag (PG_anon_exclusive) whether a mapped
anonymous page is exclusive.  Exclusive anonymous pages that are mapped
R/O can directly be mapped R/W by the COW logic in the write fault
handler.  Exclusive anonymous pages that want to be shared (fork(), KSM)
first have to be marked shared -- which will fail if there are GUP pins on
the page.  GUP is only allowed to take a pin on anonymous pages that are
exclusive.  The PT lock is the primary mechanism to synchronize
modifications of PG_anon_exclusive.  We synchronize against GUP-fast
either via the src_mm->write_protect_seq (during fork()) or via
clear/invalidate+flush of the relevant page table entry.

Special care has to be taken about swap, migration, and THPs (whereby a
PMD-mapping can be converted to a PTE mapping and we have to track
information for subpages).  Besides these, we let the rmap code handle
most magic.  For reliable R/O pins of anonymous pages, we need
FAULT_FLAG_UNSHARE logic as part of our previous approach [2], however,
it's now 100% mapcount free and I further simplified it a bit.

   is a fix
  #3-#10 are mostly rmap preparations for PG_anon_exclusive handling
   introduces PG_anon_exclusive
   uses PG_anon_exclusive and make R/W pins of anonymous pages
   reliable
   is a preparation for reliable R/O pins
   and  is reused/modified GUP-triggered unsharing for R/O GUP pins
   make R/O pins of anonymous pages reliable
   adds sanity check when (un)pinning anonymous pages

[1] https://lkml.kernel.org/r/20220131162940.210846-1-david@redhat.com
[2] https://lkml.kernel.org/r/20211217113049.23850-1-david@redhat.com
[3] https://lore.kernel.org/r/3ae33b08-d9ef-f846-56fb-645e3b9b4c66@redhat.com
[4] https://bugzilla.kernel.org/show_bug.cgi?id=215616


This patch (of 17):

In case arch_unmap_one() fails, we already did a swap_duplicate().  let's
undo that properly via swap_free().

Link: https://lkml.kernel.org/r/20220428083441.37290-1-david@redhat.com
Link: https://lkml.kernel.org/r/20220428083441.37290-2-david@redhat.com
Fixes: ca827d55eb ("mm, swap: Add infrastructure for saving page metadata on swap")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liang Zhang <zhangliang5@huawei.com>
Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com>
Cc: Oded Gabbay <oded.gabbay@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-05-09 18:20:42 -07:00
..
damon mm/damon/reclaim: fix the timer always stays active 2022-04-29 14:37:00 -07:00
kasan kasan: fix sleeping function called from invalid context on RT kernel 2022-04-29 14:36:58 -07:00
kfence mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-15 14:49:55 -07:00
backing-dev.c remove congestion tracking framework 2022-03-22 15:57:01 -07:00
balloon_compaction.c mm/balloon_compaction: make balloon page compaction callbacks static 2022-03-28 16:52:57 -04:00
bootmem_info.c bootmem: Use page->index instead of page->freelist 2022-01-06 12:27:03 +01:00
cma_debug.c
cma_sysfs.c
cma.c mm/cma: provide option to opt out from exposing pages on activation failure 2022-03-22 15:57:09 -07:00
cma.h mm/cma: provide option to opt out from exposing pages on activation failure 2022-03-22 15:57:09 -07:00
compaction.c mm: compaction: make sure highest is above the min_pfn 2022-04-28 23:16:19 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: drop protection_map[] usage 2022-04-28 23:16:12 -07:00
debug.c mm: unexport page_init_poison 2022-03-24 19:06:45 -07:00
dmapool.c mm/dmapool.c: revert "make dma pool to use kmalloc_node" 2022-01-15 16:30:28 +02:00
early_ioremap.c mm/early_ioremap: declare early_memremap_pgprot_adjust() 2022-03-22 15:57:11 -07:00
fadvise.c remove inode_congested() 2022-03-22 15:57:01 -07:00
failslab.c
filemap.c tmpfs: fix regressions from wider use of ZERO_PAGE 2022-04-15 14:49:54 -07:00
folio-compat.c mm/rmap: Convert rmap_walk() to take a folio 2022-03-21 13:01:35 -04:00
frontswap.c frontswap: remove support for multiple ops 2022-01-22 08:33:38 +02:00
gup_test.c
gup_test.h
gup.c mm/munlock: add lru_add_drain() to fix memcg_stat_test 2022-04-01 11:46:09 -07:00
highmem.c highmem: fix checks in __kmap_local_sched_{in,out} 2022-04-08 14:20:36 -10:00
hmm.c mm/hmm.c: remove unneeded local variable ret 2022-03-22 15:57:12 -07:00
huge_memory.c mm/huge_memory: Avoid calling pmd_page() on a non-leaf PMD 2022-04-07 09:43:41 -04:00
hugetlb_cgroup.c hugetlb: add hugetlb.*.numa_stat file 2022-01-15 16:30:29 +02:00
hugetlb_vmemmap.c mm/hugetlb_vmemmap: move comment block to Documentation/vm 2022-04-28 23:16:15 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: cleanup CONFIG_HUGETLB_PAGE_FREE_VMEMMAP* 2022-04-28 23:16:15 -07:00
hugetlb.c mm: hugetlb: add missing cache flushing in hugetlb_unshare_all_pmds() 2022-04-29 14:36:58 -07:00
hwpoison-inject.c mm/hwpoison: avoid the impact of hwpoison_filter() return value on mce handler 2022-03-22 15:57:07 -07:00
init-mm.c kernel/fork: Initialize mm's PASID 2022-02-14 19:51:47 +01:00
internal.h mm: compaction: clean up comment for sched contention 2022-04-28 23:16:17 -07:00
interval_tree.c
io-mapping.c
ioremap.c mm: move ioremap_page_range to vmalloc.c 2021-09-08 11:50:24 -07:00
Kconfig mm/mmap: drop arch_filter_pgprot() 2022-04-28 23:16:13 -07:00
Kconfig.debug mm: page table check 2022-01-15 16:30:28 +02:00
khugepaged.c mm/khugepaged: use vma_is_anonymous 2022-04-29 14:36:58 -07:00
kmemleak.c mm: kmemleak: take a full lowmem check in kmemleak_*_phys() 2022-04-15 14:49:56 -07:00
ksm.c ksm: count ksm merging pages for each process 2022-04-28 23:16:16 -07:00
list_lru.c mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()" 2022-04-08 14:20:36 -10:00
maccess.c asm-generic updates for 5.18 2022-03-23 18:03:08 -07:00
madvise.c mm/madvise: fix potential pte_unmap_unlock pte error 2022-04-28 23:16:09 -07:00
Makefile mm: hugetlb_vmemmap: cleanup CONFIG_HUGETLB_PAGE_FREE_VMEMMAP* 2022-04-28 23:16:15 -07:00
mapping_dirty_helpers.c mm: move tlb_flush_pending inline helpers to mm_inline.h 2022-01-15 16:30:27 +02:00
memblock.c memblock: test suite and a small cleanup 2022-03-27 13:36:06 -07:00
memcontrol.c memcg: introduce per-memcg reclaim interface 2022-04-29 14:36:59 -07:00
memfd.c memfd: fix F_SEAL_WRITE after shmem huge page allocated 2022-03-05 11:08:32 -08:00
memory_hotplug.c mm/sparse-vmemmap: add a pgmap argument to section activation 2022-04-28 23:16:15 -07:00
memory-failure.c mm, hugetlb, hwpoison: separate branch for free and in-use hugepage 2022-04-28 23:16:02 -07:00
memory.c mm/vmstat: add events for ksm cow 2022-04-28 23:16:16 -07:00
mempolicy.c mm/mempolicy: clean up the code logic in queue_pages_pte_range 2022-04-28 23:16:06 -07:00
mempool.c mm: remove spurious blkdev.h includes 2021-10-18 06:17:01 -06:00
memremap.c mm/sparse-vmemmap: improve memory savings for compound devmaps 2022-04-28 23:16:16 -07:00
memtest.c
migrate_device.c mm/migrate: Convert remove_migration_ptes() to folios 2022-03-21 13:01:35 -04:00
migrate.c mm: untangle config dependencies for demote-on-reclaim 2022-04-28 23:16:09 -07:00
mincore.c
mlock.c mm/munlock: protect the per-CPU pagevec by a local_lock_t 2022-04-01 11:46:09 -07:00
mm_init.c
mmap_lock.c
mmap.c mm/mmap: drop arch_vm_get_page_pgprot() 2022-04-28 23:16:14 -07:00
mmu_gather.c mm/mmu_gather: limit free batch count and add schedule point in tlb_batch_pages_flush 2022-04-28 23:16:12 -07:00
mmu_notifier.c mm/mmu_notifier.c: fix race in mmu_interval_notifier_remove() 2022-04-21 20:01:10 -07:00
mmzone.c Folio changes for 5.18 2022-03-22 17:03:12 -07:00
mprotect.c memory tiering: skip to scan fast memory 2022-03-22 15:57:09 -07:00
mremap.c mm/mremap: avoid unneeded do_munmap call 2022-04-28 23:16:14 -07:00
msync.c
nommu.c no-MMU: expose vmalloc_huge() for alloc_large_system_hash() 2022-04-25 10:11:49 -07:00
oom_kill.c oom_kill.c: futex: delay the OOM reaper to allow time for proper futex cleanup 2022-04-21 20:01:10 -07:00
page_alloc.c mm/page_alloc: simplify update of pgdat in wake_all_kswapds 2022-04-29 14:36:59 -07:00
page_counter.c mm/page_counter: remove an incorrect call to propagate_protected_usage() 2022-01-15 16:30:27 +02:00
page_ext.c mm: use for_each_online_node and node_online instead of open coding 2022-04-29 14:36:58 -07:00
page_idle.c mm/rmap: Constify the rmap_walk_control argument 2022-03-21 13:01:35 -04:00
page_io.c mm: fix unexpected zeroed page mapping with zram swap 2022-04-15 14:49:55 -07:00
page_isolation.c mm: wrap __find_buddy_pfn() with a necessary buddy page validation 2022-04-28 23:16:01 -07:00
page_owner.c mm/page_owner.c: record tgid 2022-03-24 19:06:44 -07:00
page_poison.c
page_reporting.c
page_reporting.h
page_table_check.c mm/page_table_check.c: use strtobool for param parsing 2022-03-22 15:57:11 -07:00
page_vma_mapped.c mm: pvmw: add support for walking devmap pages 2022-04-28 23:16:10 -07:00
page-writeback.c mm: rework calculation of bdi_min_ratio in bdi_set_min_ratio 2022-04-28 23:15:57 -07:00
pagewalk.c
percpu-internal.h mm: memcg/percpu: account extra objcg space to memory cgroups 2022-01-15 16:30:31 +02:00
percpu-km.c
percpu-stats.c mm: use vmalloc_array and vcalloc for array allocations 2022-03-08 09:30:46 -05:00
percpu-vm.c
percpu.c bitmap patches for 5.17-rc1 2022-01-23 06:20:44 +02:00
pgalloc-track.h
pgtable-generic.c mm: move tlb_flush_pending inline helpers to mm_inline.h 2022-01-15 16:30:27 +02:00
process_vm_access.c
ptdump.c mm: sparsemem: use page table lock to protect kernel pmd operations 2022-03-22 15:57:08 -07:00
readahead.c readahead: Update comments 2022-04-01 14:40:42 -04:00
rmap.c mm/rmap: fix missing swap_free() in try_to_unmap() after arch_unmap_one() failed 2022-05-09 18:20:42 -07:00
rodata_test.c
secretmem.c mm/secretmem: fix panic when growing a memfd_secret 2022-04-15 14:49:54 -07:00
shmem.c mm: shmem: make shmem_init return void 2022-04-28 23:15:58 -07:00
shuffle.c
shuffle.h
slab_common.c mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-15 14:49:55 -07:00
slab.c mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-15 14:49:55 -07:00
slab.h mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-15 14:49:55 -07:00
slob.c mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-15 14:49:55 -07:00
slub.c mm, kfence: support kmem_dump_obj() for KFENCE objects 2022-04-15 14:49:55 -07:00
sparse-vmemmap.c mm/sparse-vmemmap: improve memory savings for compound devmaps 2022-04-28 23:16:16 -07:00
sparse.c mm/sparse-vmemmap: add a pgmap argument to section activation 2022-04-28 23:16:15 -07:00
swap_cgroup.c mm: use vmalloc_array and vcalloc for array allocations 2022-03-08 09:30:46 -05:00
swap_slots.c treewide: Add missing includes masked by cgroup -> bpf dependency 2021-12-03 10:58:13 -08:00
swap_state.c Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
swap.c mm/munlock: protect the per-CPU pagevec by a local_lock_t 2022-04-01 11:46:09 -07:00
swapfile.c mm/swapfile: remove stale reuse_swap_page() 2022-03-24 19:06:51 -07:00
truncate.c Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
usercopy.c Merge branch 'akpm' (patches from Andrew) 2022-03-22 16:11:53 -07:00
userfaultfd.c userfaultfd: mark uffd_wp regardless of VM_WRITE flag 2022-04-21 20:01:09 -07:00
util.c kvmalloc: use vmalloc_huge for vmalloc allocations 2022-04-24 10:05:38 -07:00
vmacache.c
vmalloc.c vmap(): don't allow invalid pages 2022-04-28 23:16:00 -07:00
vmpressure.c mm/vmpressure: fix data-race with memcg->socket_pressure 2021-11-06 13:30:40 -07:00
vmscan.c mm/vmscan: fix comment for isolate_lru_pages 2022-04-28 23:16:04 -07:00
vmstat.c mm/vmstat: add events for ksm cow 2022-04-28 23:16:16 -07:00
workingset.c memcg: sync flush only if periodic flush is delayed 2022-04-21 20:01:09 -07:00
z3fold.c mm/z3fold: remove unneeded PAGE_HEADLESS check in free_handle() 2022-04-28 23:16:06 -07:00
zbud.c
zpool.c zpool: remove the list of pools_head 2022-01-15 16:30:31 +02:00
zsmalloc.c zsmalloc: replace get_cpu_var with local_lock 2022-01-22 08:33:37 +02:00
zswap.c mm/zswap.c: allow handling just same-value filled pages 2022-03-22 15:57:11 -07:00