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linux/mm
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Kirill A. Shutemov 73933b3315 mm: drop bogus VM_BUG_ON_PAGE assert in put_page() codepath 
My commit 8d63d99a5d ("mm: avoid tail page refcounting on non-THP
compound pages") which was merged during 4.1 merge window caused
regression:

  page:ffffea0010a15040 count:0 mapcount:1 mapping:          (null) index:0x0
  flags: 0x8000000000008014(referenced|dirty|tail)
  page dumped because: VM_BUG_ON_PAGE(page_mapcount(page) != 0)
  ------------[ cut here ]------------
  kernel BUG at mm/swap.c:134!

The problem can be reproduced by playing *two* audio files at the same
time and then stopping one of players.  I used two mplayers to trigger
this.

The VM_BUG_ON_PAGE() which triggers the bug is bogus:

Sound subsystem uses compound pages for its buffers, but unlike most
__GFP_COMP sound maps compound pages to userspace with PTEs.

In our case with two players map the buffer twice and therefore elevates
page_mapcount() on tail pages by two.  When one of players exits it
unmaps the VMA and drops page_mapcount() to one and try to release
reference on the page with put_page().

My commit changes which path it takes under put_compound_page().  It hits
put_unrefcounted_compound_page() where VM_BUG_ON_PAGE() is.  It sees
page_mapcount() == 1.  The function wrongly assumes that subpages of
compound page cannot be be mapped by itself with PTEs..

The solution is simply drop the VM_BUG_ON_PAGE().

Note: there's no need to move the check under put_page_testzero().
Allocator will check the mapcount by itself before putting on free list.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-24 17:49:42 -07:00
..
kasan mm/mempool.c: kasan: poison mempool elements 2015-04-15 16:35:20 -07:00
backing-dev.c block: discard bdi_unregister() in favour of bdi_destroy() 2015-05-28 10:12:42 -06:00
balloon_compaction.c mm/balloon_compaction: fix deflation when compaction is disabled 2014-10-29 16:33:15 -07:00
bootmem.c mem-hotplug: reset node managed pages when hot-adding a new pgdat 2014-11-13 16:17:06 -08:00
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.c: remove blank lines before DEFINE_SIMPLE_ATTRIBUTE() 2015-04-15 16:35:20 -07:00
cma.c mm: cma: add trace events for CMA allocations and freeings 2015-04-15 16:35:19 -07:00
cma.h mm: cma: allocation trigger 2015-04-14 16:49:00 -07:00
compaction.c mm/compaction.c: fix "suitable_migration_target() unused" warning 2015-04-15 16:35:20 -07:00
debug-pagealloc.c mm/debug-pagealloc: make debug-pagealloc boottime configurable 2014-12-13 12:42:48 -08:00
debug.c mm: account pmd page tables to the process 2015-02-11 17:06:04 -08:00
dmapool.c mm/dmapool.c: fixed a brace coding style issue 2014-10-09 22:26:00 -04:00
early_ioremap.c mm: create generic early_ioremap() support 2014-04-07 16:36:15 -07:00
fadvise.c vfs: remove get_xip_mem 2015-02-16 17:56:03 -08:00
failslab.c
filemap.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-04-16 23:27:56 -04:00
frontswap.c mm/frontswap.c: fix the condition in BUG_ON 2014-12-10 17:41:08 -08:00
gup.c mm: use READ_ONCE() for non-scalar types 2015-04-15 16:35:18 -07:00
highmem.c mm/highmem: make kmap cache coloring aware 2014-08-06 18:01:22 -07:00
huge_memory.c thp: cleanup how khugepaged enters freezer 2015-06-24 17:49:41 -07:00
hugetlb_cgroup.c mm: page_counter: pull "-1" handling out of page_counter_memparse() 2015-02-11 17:06:02 -08:00
hugetlb.c mm/hugetlb: reduce arch dependent code about huge_pmd_unshare 2015-06-24 17:49:41 -07:00
hwpoison-inject.c mm/hwpoison-inject: check PageLRU of hpage 2015-05-05 17:10:11 -07:00
init-mm.c
internal.h mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
Kconfig mm: cma: debugfs interface 2015-04-14 16:49:00 -07:00
Kconfig.debug mm/debug_pagealloc: remove obsolete Kconfig options 2015-01-08 15:10:52 -08:00
kmemcheck.c mm/slab_common: move kmem_cache definition to internal header 2014-10-09 22:25:50 -04:00
kmemleak-test.c mm/kmemleak-test.c: use pr_fmt for logging 2014-06-06 16:08:18 -07:00
kmemleak.c gfp: add __GFP_NOACCOUNT 2015-05-14 17:55:51 -07:00
ksm.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
list_lru.c memcg: reparent list_lrus and free kmemcg_id on css offline 2015-02-12 18:54:10 -08:00
maccess.c
madvise.c vfs: remove get_xip_mem 2015-02-16 17:56:03 -08:00
Makefile mm: move memtest under mm 2015-04-14 16:49:06 -07:00
memblock.c mm/memblock.c: add debug output for memblock_add() 2015-04-15 16:35:19 -07:00
memcontrol.c mm: memcontrol: fix false-positive VM_BUG_ON() on -rt 2015-06-10 16:43:43 -07:00
memory_hotplug.c mm/memory_hotplug.c: set zone->wait_table to null after freeing it 2015-06-10 16:43:43 -07:00
memory-failure.c mm, hwpoison: remove obsolete "Notebook" todo list 2015-06-24 17:49:41 -07:00
memory.c sched/preempt, mm/fault: Trigger might_sleep() in might_fault() with disabled pagefaults 2015-05-19 08:39:14 +02:00
mempolicy.c mm, numa: really disable NUMA balancing by default on single node machines 2015-05-14 17:55:51 -07:00
mempool.c mm/mempool.c: kasan: poison mempool elements 2015-04-15 16:35:20 -07:00
memtest.c memtest: use phys_addr_t for physical addresses 2015-04-14 16:49:06 -07:00
migrate.c mm/migrate: check-before-clear PageSwapCache 2015-04-15 16:35:17 -07:00
mincore.c mincore: apply page table walker on do_mincore() 2015-02-11 17:06:06 -08:00
mlock.c mm: move mm_populate()-related code to mm/gup.c 2015-04-14 16:49:00 -07:00
mm_init.c mm/mm_init.c: mark mminit_loglevel __meminitdata 2015-02-12 18:54:11 -08:00
mmap.c mm/mmap.c: use while instead of if+goto 2015-04-15 16:35:19 -07:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c mmu_notifier: add the callback for mmu_notifier_invalidate_range() 2014-11-13 13:46:09 +11:00
mmzone.c mm: microoptimize zonelist operations 2015-02-11 17:06:02 -08:00
mprotect.c mm: fix mprotect() behaviour on VM_LOCKED VMAs 2015-06-24 17:49:41 -07:00
mremap.c mm: new arch_remap() hook 2015-06-24 17:49:41 -07:00
msync.c mm: remove rest usage of VM_NONLINEAR and pte_file() 2015-02-10 14:30:31 -08:00
nobootmem.c mem-hotplug: reset node managed pages when hot-adding a new pgdat 2014-11-13 16:17:06 -08:00
nommu.c nommu: use __vfs_read() 2015-04-11 22:27:56 -04:00
oom_kill.c mm/oom_kill.c: fix typo in comment 2015-04-15 16:35:16 -07:00
page_alloc.c mm: only define hashdist variable when needed 2015-06-24 17:49:41 -07:00
page_counter.c mm: page_counter: pull "-1" handling out of page_counter_memparse() 2015-02-11 17:06:02 -08:00
page_ext.c mm/page_owner: keep track of page owners 2014-12-13 12:42:48 -08:00
page_io.c direct_IO: remove rw from a_ops->direct_IO() 2015-04-11 22:29:45 -04:00
page_isolation.c CMA: page_isolation: check buddy before accessing it 2015-05-14 17:55:51 -07:00
page_owner.c mm/page_owner.c: remove unnecessary stack_trace field 2015-02-11 17:06:07 -08:00
page-writeback.c writeback: use |1 instead of +1 to protect against div by zero 2015-04-23 10:36:33 -06:00
pagewalk.c mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed to callers 2015-03-25 16:20:30 -07:00
percpu-km.c percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated 2014-09-02 14:46:05 -04:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c percpu: Fix trivial typos in comments 2015-03-24 13:41:54 -04:00
pgtable-generic.c mm: convert p[te|md]_mknonnuma and remaining page table manipulations 2015-02-12 18:54:08 -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 fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info 2015-01-20 14:03:04 -07:00
rmap.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
shmem.c Merge branch 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-06-22 12:51:21 -07:00
slab_common.c slab: correct size_index table before replacing the bootstrap kmem_cache_node 2015-06-24 17:49:41 -07:00
slab.c slab: correct size_index table before replacing the bootstrap kmem_cache_node 2015-06-24 17:49:41 -07:00
slab.h slab: correct size_index table before replacing the bootstrap kmem_cache_node 2015-06-24 17:49:41 -07:00
slob.c slob: make slob_alloc_node() static and remove EXPORT_SYMBOL() 2015-04-14 16:48:59 -07:00
slub.c slab: correct size_index table before replacing the bootstrap kmem_cache_node 2015-06-24 17:49:41 -07:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap_cgroup.c mm: page_cgroup: rename file to mm/swap_cgroup.c 2014-12-10 17:41:09 -08:00
swap_state.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
swap.c mm: drop bogus VM_BUG_ON_PAGE assert in put_page() codepath 2015-06-24 17:49:42 -07:00
swapfile.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
truncate.c mm: rename deactivate_page to deactivate_file_page 2015-04-15 16:35:17 -07:00
util.c mm: uninline and cleanup page-mapping related helpers 2015-04-15 16:35:19 -07:00
vmacache.c mm,vmacache: count number of system-wide flushes 2014-12-13 12:42:48 -08:00
vmalloc.c mm/vmalloc: get rid of dirty bitmap inside vmap_block structure 2015-04-15 16:35:18 -07:00
vmpressure.c mm/vmpressure.c: fix race in vmpressure_work_fn() 2014-12-02 17:32:07 -08:00
vmscan.c Merge branch 'akpm' (patches from Andrew) 2015-02-12 18:54:28 -08:00
vmstat.c vmstat: Reduce time interval to stat update on idle cpu 2015-02-11 17:06:07 -08:00
workingset.c list_lru: add helpers to isolate items 2015-02-12 18:54:10 -08:00
zbud.c mm/zpool: add name argument to create zpool 2015-02-12 18:54:12 -08:00
zpool.c mm/zpool: add name argument to create zpool 2015-02-12 18:54:12 -08:00
zsmalloc.c zsmalloc: fix a null pointer dereference in destroy_handle_cache() 2015-06-10 16:43:43 -07:00
zswap.c mm/zpool: add name argument to create zpool 2015-02-12 18:54:12 -08:00