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linux/mm
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Junil Lee c102f07ca0 zsmalloc: fix migrate_zspage-zs_free race condition 
record_obj() in migrate_zspage() does not preserve handle's
HANDLE_PIN_BIT, set by find_aloced_obj()->trypin_tag(), and implicitly
(accidentally) un-pins the handle, while migrate_zspage() still performs
an explicit unpin_tag() on the that handle.  This additional explicit
unpin_tag() introduces a race condition with zs_free(), which can pin
that handle by this time, so the handle becomes un-pinned.

Schematically, it goes like this:

  CPU0                                        CPU1
  migrate_zspage
    find_alloced_obj
      trypin_tag
        set HANDLE_PIN_BIT                    zs_free()
                                                pin_tag()
  obj_malloc() -- new object, no tag
  record_obj() -- remove HANDLE_PIN_BIT           set HANDLE_PIN_BIT
  unpin_tag()  -- remove zs_free's HANDLE_PIN_BIT

The race condition may result in a NULL pointer dereference:

  Unable to handle kernel NULL pointer dereference at virtual address 00000000
  CPU: 0 PID: 19001 Comm: CookieMonsterCl Tainted:
  PC is at get_zspage_mapping+0x0/0x24
  LR is at obj_free.isra.22+0x64/0x128
  Call trace:
     get_zspage_mapping+0x0/0x24
     zs_free+0x88/0x114
     zram_free_page+0x64/0xcc
     zram_slot_free_notify+0x90/0x108
     swap_entry_free+0x278/0x294
     free_swap_and_cache+0x38/0x11c
     unmap_single_vma+0x480/0x5c8
     unmap_vmas+0x44/0x60
     exit_mmap+0x50/0x110
     mmput+0x58/0xe0
     do_exit+0x320/0x8dc
     do_group_exit+0x44/0xa8
     get_signal+0x538/0x580
     do_signal+0x98/0x4b8
     do_notify_resume+0x14/0x5c

This patch keeps the lock bit in migration path and update value
atomically.

Signed-off-by: Junil Lee <junil0814.lee@lge.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: <stable@vger.kernel.org> [4.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
..
kasan kasan: fix kmemleak false-positive in kasan_module_alloc() 2015-11-20 16:17:32 -08:00
backing-dev.c mm: memcontrol: export root_mem_cgroup 2016-01-14 16:00:49 -08:00
balloon_compaction.c virtio_balloon: fix race between migration and ballooning 2016-01-12 20:47:06 +02:00
bootmem.c x86/mm: Introduce max_possible_pfn 2015-12-06 12:46:31 +01:00
cleancache.c cleancache: remove limit on the number of cleancache enabled filesystems 2015-04-14 16:49:03 -07:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
cma.c mm/cma.c: suppress warning 2015-11-05 19:34:48 -08:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
compaction.c mm/compaction.c: __compact_pgdat() code cleanuup 2016-01-14 16:00:49 -08:00
debug-pagealloc.c
debug.c mm: rework mapcount accounting to enable 4k mapping of THPs 2016-01-15 17:56:32 -08:00
dmapool.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
early_ioremap.c mm/early_ioremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
fadvise.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
failslab.c mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 2015-11-06 17:50:42 -08:00
filemap.c mm: differentiate page_mapped() from page_mapcount() for compound pages 2016-01-15 17:56:32 -08:00
frame_vector.c mm: fix docbook comment for get_vaddr_frames() 2015-11-05 19:34:48 -08:00
frontswap.c frontswap: allow multiple backends 2015-06-24 17:49:45 -07:00
gup.c mm: bring in additional flag for fixup_user_fault to signal unlock 2016-01-15 17:56:32 -08:00
highmem.c
huge_memory.c thp: fix interrupt unsafe locking in split_huge_page() 2016-01-20 17:09:18 -08:00
hugetlb_cgroup.c mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
hugetlb.c mm: rework mapcount accounting to enable 4k mapping of THPs 2016-01-15 17:56:32 -08:00
hwpoison-inject.c hwpoison: use page_cgroup_ino for filtering by memcg 2015-09-10 13:29:01 -07:00
init-mm.c
internal.h thp: reintroduce split_huge_page() 2016-01-15 17:56:32 -08:00
interval_tree.c
Kconfig mm: re-enable THP 2016-01-15 17:56:32 -08:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c Revert "gfp: add __GFP_NOACCOUNT" 2016-01-14 16:00:49 -08:00
ksm.c mm/ksm.c: mark stable page dirty 2016-01-15 17:56:32 -08:00
list_lru.c memcg: simplify and inline __mem_cgroup_from_kmem 2015-11-05 19:34:48 -08:00
maccess.c mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe 2015-11-05 19:34:48 -08:00
madvise.c mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called 2016-01-15 17:56:32 -08:00
Makefile media updates for v4.3-rc1 2015-09-11 16:42:39 -07:00
memblock.c mm/memblock: introduce for_each_memblock_type() 2016-01-14 16:00:49 -08:00
memcontrol.c memcg: only free spare array when readers are done 2016-01-15 17:56:32 -08:00
memory_hotplug.c x86, mm: introduce vmem_altmap to augment vmemmap_populate() 2016-01-15 17:56:32 -08:00
memory-failure.c mm: soft-offline: exit with failure for non anonymous thp 2016-01-15 17:56:32 -08:00
memory.c mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd 2016-01-15 17:56:32 -08:00
mempolicy.c mm: mempolicy: skip non-migratable VMAs when setting MPOL_MF_LAZY 2016-01-15 17:56:32 -08:00
mempool.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c thp: introduce deferred_split_huge_page() 2016-01-15 17:56:32 -08:00
mincore.c mm, thp: remove infrastructure for handling splitting PMDs 2016-01-15 17:56:32 -08:00
mlock.c mm/mlock.c: change can_do_mlock return value type to boolean 2016-01-15 17:56:32 -08:00
mm_init.c mm: meminit: remove mminit_verify_page_links 2015-06-30 19:44:56 -07:00
mmap.c mm: fix locking order in mm_take_all_locks() 2016-01-15 17:56:32 -08:00
mmu_context.c
mmu_notifier.c mmu-notifier: add clear_young callback 2015-09-10 13:29:01 -07:00
mmzone.c mm/mmzone.c: memmap_valid_within() can be boolean 2016-01-14 16:00:49 -08:00
mprotect.c mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd 2016-01-15 17:56:32 -08:00
mremap.c mm, thp: remove infrastructure for handling splitting PMDs 2016-01-15 17:56:32 -08:00
msync.c mm/msync: use offset_in_page macro 2015-11-05 19:34:48 -08:00
nobootmem.c x86/mm: Introduce max_possible_pfn 2015-12-06 12:46:31 +01:00
nommu.c kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
oom_kill.c mm, shmem: add internal shmem resident memory accounting 2016-01-14 16:00:49 -08:00
page_alloc.c mm/page_alloc.c: remove unused struct zone *z variable 2016-01-15 17:56:32 -08:00
page_counter.c mm: page_counter: let page_counter_try_charge() return bool 2015-11-05 19:34:48 -08:00
page_ext.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
page_idle.c mm: add page_check_address_transhuge() helper 2016-01-15 17:56:32 -08:00
page_io.c fs: use helper bio_add_page() instead of open coding on bi_io_vec 2015-08-13 12:32:00 -06:00
page_isolation.c mm/page_isolation: do some cleanup in "undo_isolate_page_range" 2016-01-15 17:56:32 -08:00
page_owner.c mm/page_owner: set correct gfp_mask on page_owner 2015-07-17 16:39:54 -07:00
page-writeback.c mm: page_alloc: generalize the dirty balance reserve 2016-01-14 16:00:49 -08:00
pagewalk.c thp: rename split_huge_page_pmd() to split_huge_pmd() 2016-01-15 17:56:32 -08:00
percpu-km.c
percpu-vm.c
percpu.c mm/percpu: use offset_in_page macro 2015-11-05 19:34:48 -08:00
pgtable-generic.c mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd 2016-01-15 17:56:32 -08:00
process_vm_access.c process_vm_access: switch to {compat_,}import_iovec() 2015-04-11 22:27:12 -04:00
quicklist.c
readahead.c mm: move lru_to_page to mm_inline.h 2016-01-14 16:00:49 -08:00
rmap.c mm: fix locking order in mm_take_all_locks() 2016-01-15 17:56:32 -08:00
shmem.c memcg: adjust to support new THP refcounting 2016-01-15 17:56:32 -08:00
slab_common.c slab: add SLAB_ACCOUNT flag 2016-01-14 16:00:49 -08:00
slab.c mm/slab.c: add a helper function get_first_slab 2016-01-14 16:00:49 -08:00
slab.h slab: add SLAB_ACCOUNT flag 2016-01-14 16:00:49 -08:00
slob.c slab/slub: adjust kmem_cache_alloc_bulk API 2015-11-22 11:58:44 -08:00
slub.c page-flags: define PG_locked behavior on compound pages 2016-01-15 17:56:32 -08:00
sparse-vmemmap.c x86, mm: introduce vmem_altmap to augment vmemmap_populate() 2016-01-15 17:56:32 -08:00
sparse.c x86, mm: introduce vmem_altmap to augment vmemmap_populate() 2016-01-15 17:56:32 -08:00
swap_cgroup.c
swap_state.c mm: support madvise(MADV_FREE) 2016-01-15 17:56:32 -08:00
swap.c mm, x86: get_user_pages() for dax mappings 2016-01-15 17:56:32 -08:00
swapfile.c mm: make swapoff more robust against soft dirty 2016-01-15 17:56:32 -08:00
truncate.c memcg: add per cgroup dirty page accounting 2015-06-02 08:33:33 -06:00
userfaultfd.c memcg: adjust to support new THP refcounting 2016-01-15 17:56:32 -08:00
util.c mm: prepare page_referenced() and page_idle to new THP refcounting 2016-01-15 17:56:32 -08:00
vmacache.c mm/vmacache: inline vmacache_valid_mm() 2015-11-05 19:34:48 -08:00
vmalloc.c mm/vmalloc.c: use macro IS_ALIGNED to judge the aligment 2016-01-15 17:56:32 -08:00
vmpressure.c memcg: avoid vmpressure oops when memcg disabled 2016-01-14 16:00:49 -08:00
vmscan.c mm: support madvise(MADV_FREE) 2016-01-15 17:56:32 -08:00
vmstat.c mm: support madvise(MADV_FREE) 2016-01-15 17:56:32 -08:00
workingset.c
zbud.c mm/zbud.c: use list_last_entry() instead of list_tail_entry() 2016-01-15 11:40:52 -08:00
zpool.c mm: zsmalloc: constify struct zs_pool name 2015-11-06 17:50:42 -08:00
zsmalloc.c zsmalloc: fix migrate_zspage-zs_free race condition 2016-01-20 17:09:18 -08:00
zswap.c mm/zswap: change incorrect strncmp use to strcmp 2015-12-18 14:25:40 -08:00