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Linus Torvalds 10d20bd25e shmem: fix shm fallocate() list corruption 
The shmem hole punching with fallocate(FALLOC_FL_PUNCH_HOLE) does not
want to race with generating new pages by faulting them in.

However, the wait-queue used to delay the page faulting has a serious
problem: the wait queue head (in shmem_fallocate()) is allocated on the
stack, and the code expects that "wake_up_all()" will make sure that all
the queue entries are gone before the stack frame is de-allocated.

And that is not at all necessarily the case.

Yes, a normal wake-up sequence will remove the wait-queue entry that
caused the wakeup (see "autoremove_wake_function()"), but the key
wording there is "that caused the wakeup".  When there are multiple
possible wakeup sources, the wait queue entry may well stay around.

And _particularly_ in a page fault path, we may be faulting in new pages
from user space while we also have other things going on, and there may
well be other pending wakeups.

So despite the "wake_up_all()", it's not at all guaranteed that all list
entries are removed from the wait queue head on the stack.

Fix this by introducing a new wakeup function that removes the list
entry unconditionally, even if the target process had already woken up
for other reasons.  Use that "synchronous" function to set up the
waiters in shmem_fault().

This problem has never been seen in the wild afaik, but Dave Jones has
reported it on and off while running trinity.  We thought we fixed the
stack corruption with the blk-mq rq_list locking fix (commit
7fe311302f7d: "blk-mq: update hardware and software queues for sleeping
alloc"), but it turns out there was _another_ stack corruptor hiding
in the trinity runs.

Vegard Nossum (also running trinity) was able to trigger this one fairly
consistently, and made us look once again at the shmem code due to the
faults often being in that area.

Reported-and-tested-by: Vegard Nossum <vegard.nossum@oracle.com>.
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2016-12-06 08:59:05 -08:00
..
kasan kasan: support use-after-scope detection 2016-11-30 16:32:52 -08:00
Kconfig Allow KASAN and HOTPLUG_MEMORY to co-exist when doing build testing 2016-10-27 16:23:01 -07:00
Kconfig.debug PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO 2016-09-13 02:35:27 +02:00
Makefile Disable the __builtin_return_address() warning globally after all 2016-10-12 10:23:41 -07:00
backing-dev.c block: fix bdi vs gendisk lifetime mismatch 2016-08-04 14:19:16 -06:00
balloon_compaction.c mm: balloon: use general non-lru movable page feature 2016-07-26 16:19:19 -07:00
bootmem.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
cleancache.c cleancache: constify cleancache_ops structure 2016-01-27 09:09:57 -05:00
cma.c mm/cma.c: check the max limit for cma allocation 2016-11-11 08:12:37 -08:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
compaction.c mm, compaction: restrict fragindex to costly orders 2016-10-07 18:46:29 -07:00
debug.c mm: clarify why we avoid page_mapcount() for slab pages in dump_page() 2016-10-07 18:46:29 -07:00
debug_page_ref.c mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
dmapool.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
early_ioremap.c mm/early_ioremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
fadvise.c mm/fadvise.c: do not discard partial pages with POSIX_FADV_DONTNEED 2016-06-09 14:23:11 -07:00
failslab.c mm: fault-inject take over bootstrap kmem_cache check 2016-03-15 16:55:16 -07:00
filemap.c mm/filemap: don't allow partially uptodate page for pipes 2016-11-11 08:12:37 -08:00
frame_vector.c mm: replace get_vaddr_frames() write/force parameters with gup_flags 2016-10-19 08:11:24 -07:00
frontswap.c mm, frontswap: convert frontswap_enabled to static key 2016-07-26 16:19:19 -07:00
gup.c mm: unexport __get_user_pages() 2016-10-24 19:13:20 -07:00
highmem.c mm/highmem: make nr_free_highpages() handles all highmem zones by itself 2016-05-19 19:12:14 -07:00
huge_memory.c mremap: move_ptes: check pte dirty after its removal 2016-11-29 08:20:24 -08:00
hugetlb.c mm/hugetlb: fix huge page reservation leak in private mapping error paths 2016-11-11 08:12:37 -08:00
hugetlb_cgroup.c mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size 2016-05-20 17:58:30 -07:00
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 mm, compaction: make full priority ignore pageblock suitability 2016-10-07 18:46:29 -07:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
khugepaged.c mm, thp: propagation of conditional compilation in khugepaged.c 2016-11-30 16:32:52 -08:00
kmemcheck.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak-test.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak.c mm: kmemleak: scan .data.ro_after_init 2016-11-11 08:12:37 -08:00
ksm.c mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node() 2016-10-07 18:46:29 -07:00
list_lru.c mm/list_lru.c: avoid error-path NULL pointer deref 2016-10-27 18:43:42 -07:00
maccess.c x86: remove more uaccess_32.h complexity 2016-05-22 17:21:27 -07:00
madvise.c mm: make mmap_sem for write waits killable for mm syscalls 2016-05-23 17:04:14 -07:00
memblock.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
memcontrol.c mm: memcontrol: do not recurse in direct reclaim 2016-10-27 18:43:43 -07:00
memory-failure.c mm: hwpoison: fix thp split handling in memory_failure() 2016-11-11 08:12:37 -08:00
memory.c mm: replace access_process_vm() write parameter with gup_flags 2016-10-19 08:31:25 -07:00
memory_hotplug.c mm: remove unused variable in memory hotplug 2016-10-27 15:49:12 -07:00
mempolicy.c mm: replace get_user_pages() write/force parameters with gup_flags 2016-10-19 08:11:43 -07:00
mempool.c Revert "mm, mempool: only set __GFP_NOMEMALLOC if there are free elements" 2016-07-28 16:07:41 -07:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c mm: vm_page_prot: update with WRITE_ONCE/READ_ONCE 2016-10-07 18:46:29 -07:00
mincore.c mm, swap: use offset of swap entry as key of swap cache 2016-10-07 18:46:28 -07:00
mlock.c thp: fix corner case of munlock() of PTE-mapped THPs 2016-11-30 16:32:52 -08:00
mm_init.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
mmap.c mm: vma_merge: correct false positive from __vma_unlink->validate_mm_rb 2016-10-07 18:46:29 -07:00
mmu_context.c mm/mmu_context, sched/core: Fix mmu_context.h assumption 2016-04-28 11:44:19 +02:00
mmu_notifier.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
mmzone.c mm, page_alloc: inline the fast path of the zonelist iterator 2016-05-19 19:12:14 -07:00
mprotect.c mm/numa: Remove duplicated include from mprotect.c 2016-10-19 17:28:48 +02:00
mremap.c mremap: move_ptes: check pte dirty after its removal 2016-11-29 08:20:24 -08:00
msync.c mm/msync: use offset_in_page macro 2015-11-05 19:34:48 -08:00
nobootmem.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
nommu.c mm: unexport __get_user_pages() 2016-10-24 19:13:20 -07:00
oom_kill.c oom: print nodemask in the oom report 2016-10-07 18:46:29 -07:00
page-writeback.c mm: don't use radix tree writeback tags for pages in swap cache 2016-10-07 18:46:28 -07:00
page_alloc.c mm: remove extra newline from allocation stall warning 2016-11-11 08:12:37 -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/page_ext: support extra space allocation by page_ext user 2016-10-07 18:46:27 -07:00
page_idle.c mm, vmscan: move lru_lock to the node 2016-07-28 16:07:41 -07:00
page_io.c mm/page_io.c: replace some BUG_ON()s with VM_BUG_ON_PAGE() 2016-10-07 18:46:29 -07:00
page_isolation.c mm/page_isolation: fix typo: "paes" -> "pages" 2016-10-07 18:46:29 -07:00
page_owner.c mm/page_owner: don't define fields on struct page_ext by hard-coding 2016-10-07 18:46:27 -07:00
page_poison.c mm: check the return value of lookup_page_ext for all call sites 2016-06-03 15:06:22 -07:00
pagewalk.c thp: rename split_huge_page_pmd() to split_huge_pmd() 2016-01-15 17:56:32 -08:00
percpu-km.c mm: percpu: use pr_fmt to prefix output 2016-03-17 15:09:34 -07:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c mm/percpu.c: fix potential memory leakage for pcpu_embed_first_chunk() 2016-10-05 11:52:55 -04:00
pgtable-generic.c mm/thp/migration: switch from flush_tlb_range to flush_pmd_tlb_range 2016-03-17 15:09:34 -07:00
process_vm_access.c mm: remove write/force parameters from __get_user_pages_unlocked() 2016-10-18 14:13:37 -07:00
quicklist.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
readahead.c mm: silently skip readahead for DAX inodes 2016-08-26 17:39:35 -07:00
rmap.c rmap: fix compound check logic in page_remove_file_rmap 2016-08-10 16:40:56 -07:00
shmem.c shmem: fix shm fallocate() list corruption 2016-12-06 08:59:05 -08:00
slab.c mm/slab: improve performance of gathering slabinfo stats 2016-10-27 18:43:43 -07:00
slab.h mm/slab: improve performance of gathering slabinfo stats 2016-10-27 18:43:43 -07:00
slab_common.c memcg: prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB 2016-11-11 08:12:37 -08:00
slob.c mm: slab: free kmem_cache_node after destroy sysfs file 2016-02-18 16:23:24 -08:00
slub.c slub: Convert to hotplug state machine 2016-09-06 18:30:20 +02:00
sparse-vmemmap.c treewide: replace obsolete _refok by __ref 2016-08-02 17:31:41 -04:00
sparse.c treewide: replace obsolete _refok by __ref 2016-08-02 17:31:41 -04:00
swap.c thp: reduce usage of huge zero page's atomic counter 2016-10-07 18:46:28 -07:00
swap_cgroup.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
swap_state.c mm, swap: use offset of swap entry as key of swap cache 2016-10-07 18:46:28 -07:00
swapfile.c swapfile: fix memory corruption via malformed swapfile 2016-11-11 08:12:37 -08:00
truncate.c mm: fix false-positive WARN_ON() in truncate/invalidate for hugetlb 2016-11-30 16:32:52 -08:00
usercopy.c mm: usercopy: Check for module addresses 2016-09-20 16:07:39 -07:00
userfaultfd.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
util.c Merge branch 'mm-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-22 09:39:10 -07:00
vmacache.c mm: unrig VMA cache hit ratio 2016-10-07 18:46:27 -07:00
vmalloc.c mm: consolidate warn_alloc_failed users 2016-10-07 18:46:29 -07:00
vmpressure.c mm/vmpressure.c: fix subtree pressure detection 2016-02-03 08:28:43 -08:00
vmscan.c mm, vmscan: add cond_resched() into shrink_node_memcg() 2016-12-02 18:48:03 -08:00
vmstat.c seq/proc: modify seq_put_decimal_[u]ll to take a const char *, not char 2016-10-07 18:46:30 -07:00
workingset.c mm: workingset: fix NULL ptr in count_shadow_nodes 2016-12-02 18:48:03 -08:00
z3fold.c mm/z3fold.c: avoid modifying HEADLESS page and minor cleanup 2016-06-03 16:02:55 -07:00
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: Delete an unnecessary check before the function call "iput" 2016-07-28 16:07:41 -07:00
zswap.c mm/zswap: use workqueue to destroy pool 2016-05-20 17:58:30 -07:00