Michal Hocko 3f70dc38ce mm: make sure that kthreads will not refault oom reaped memory ... There are only few use_mm() users in the kernel right now. Most of them write to the target memory but vhost driver relies on copy_from_user/get_user from a kernel thread context. This makes it impossible to reap the memory of an oom victim which shares the mm with the vhost kernel thread because it could see a zero page unexpectedly and theoretically make an incorrect decision visible outside of the killed task context. To quote Michael S. Tsirkin: : Getting an error from __get_user and friends is handled gracefully. : Getting zero instead of a real value will cause userspace : memory corruption. The vhost kernel thread is bound to an open fd of the vhost device which is not tight to the mm owner life cycle in general. The device fd can be inherited or passed over to another process which means that we really have to be careful about unexpected memory corruption because unlike for normal oom victims the result will be visible outside of the oom victim context. Make sure that no kthread context (users of use_mm) can ever see corrupted data because of the oom reaper and hook into the page fault path by checking MMF_UNSTABLE mm flag. __oom_reap_task_mm will set the flag before it starts unmapping the address space while the flag is checked after the page fault has been handled. If the flag is set then SIGBUS is triggered so any g-u-p user will get a error code. Regular tasks do not need this protection because all which share the mm are killed when the mm is reaped and so the corruption will not outlive them. This patch shouldn't have any visible effect at this moment because the OOM killer doesn't invoke oom reaper for tasks with mm shared with kthreads yet. Link: http://lkml.kernel.org/r/1472119394-11342-9-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: "Michael S. Tsirkin" <mst@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2016-10-07 18:46:28 -07:00
..
kasan	kasan: remove the unnecessary WARN_ONCE from quarantine.c	2016-08-11 16:58:14 -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: convert printk(KERN_<LEVEL> to pr_<level>	2016-03-17 15:09:34 -07:00
cleancache.c	cleancache: constify cleancache_ops structure	2016-01-27 09:09:57 -05:00
cma_debug.c	mm/cma_debug: correct size input to bitmap function	2015-07-17 16:39:54 -07:00
cma.c	mm/cma: silence warnings due to max() usage	2016-05-27 14:49:37 -07:00
cma.h	mm: cma: mark cma_bitmap_maxno() inline in header	2015-08-14 15:56:32 -07:00
compaction.c	mm, compaction: require only min watermarks for non-costly orders	2016-10-07 18:46:27 -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
debug.c	mm: avoid endless recursion in dump_page()	2016-09-19 15:36:16 -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	do_generic_file_read(): fail immediately if killed	2016-10-07 18:46:27 -07:00
frame_vector.c	mm/gup: Switch all callers of get_user_pages() to not pass tsk/mm	2016-02-16 10:11:12 +01:00
frontswap.c	mm, frontswap: convert frontswap_enabled to static key	2016-07-26 16:19:19 -07:00
gup.c	- ARM: GICv3 ITS emulation and various fixes. Removal of the old	2016-08-02 16:11:27 -04:00
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	Merge branch 'linus' into sched/core, to pick up fixes	2016-09-30 10:44:27 +02:00
hugetlb_cgroup.c	mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size	2016-05-20 17:58:30 -07:00
hugetlb.c	mm/hugetlb: fix incorrect hugepages count during mem hotplug	2016-08-11 16:58:13 -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 whole_zone flag ignore cached scanner positions	2016-10-07 18:46:27 -07:00
interval_tree.c	mm: replace vma->sharead.linear with vma->shared	2015-02-10 14:30:31 -08:00
Kconfig	mm: clarify COMPACTION Kconfig text	2016-08-26 17:39:35 -07:00
Kconfig.debug	PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO	2016-09-13 02:35:27 +02:00
khugepaged.c	mm, thp: fix leaking mapped pte in __collapse_huge_page_swapin()	2016-09-19 15:36:16 -07:00
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	kmemleak: don't hang if user disables scanning early	2016-07-28 16:07:41 -07:00
ksm.c	mm,ksm: fix endless looping in allocating memory when ksm enable	2016-09-28 16:19:01 -07:00
list_lru.c	mm: memcontrol: move kmem accounting code to CONFIG_MEMCG	2016-01-20 17:09:18 -08:00
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
Makefile	Implements HARDENED_USERCOPY verification of copy_to_user/copy_from_user	2016-08-08 14:48:14 -07:00
memblock.c	mm/memblock.c: fix NULL dereference error	2016-08-04 20:02:09 -04:00
memcontrol.c	mm: memcontrol: add sanity checks for memcg->id.ref on get/put	2016-10-07 18:46:26 -07:00
memory_hotplug.c	mem-hotplug: use nodes that contain memory as mask in new_node_page()	2016-09-28 16:19:02 -07:00
memory-failure.c	mm: hwpoison: remove incorrect comments	2016-07-28 16:07:41 -07:00
memory.c	mm: make sure that kthreads will not refault oom reaped memory	2016-10-07 18:46:28 -07:00
mempolicy.c	mm, mempolicy: task->mempolicy must be NULL before dropping final reference	2016-09-01 17:52:01 -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, thp: remove __GFP_NORETRY from khugepaged and madvised allocations	2016-07-28 16:07:41 -07:00
mincore.c	mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage	2016-04-04 10:41:08 -07:00
mlock.c	mm, vmscan: move LRU lists to node	2016-07-28 16:07:41 -07:00
mm_init.c	mm: convert printk(KERN_<LEVEL> to pr_<level>	2016-03-17 15:09:34 -07:00
mmap.c	Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2016-10-03 17:29:01 -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: thp: check pmd_trans_unstable() after split_huge_pmd()	2016-07-26 16:19:19 -07:00
mremap.c	mm: thp: check pmd_trans_unstable() after split_huge_pmd()	2016-07-26 16:19:19 -07:00
msync.c	mm/msync: use offset_in_page macro	2015-11-05 19:34:48 -08:00
nobootmem.c	mm: convert printk(KERN_<LEVEL> to pr_<level>	2016-03-17 15:09:34 -07:00
nommu.c	mm: introduce fault_env	2016-07-26 16:19:19 -07:00
oom_kill.c	mm: make sure that kthreads will not refault oom reaped memory	2016-10-07 18:46:28 -07:00
page_alloc.c	mm/page_ext: support extra space allocation by page_ext user	2016-10-07 18:46:27 -07:00
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: fix the page_swap_info() BUG_ON check	2016-09-19 15:36:17 -07:00
page_isolation.c	mm/page_isolation: clean up confused code	2016-07-26 16:19:19 -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
page-writeback.c	mm, vmscan: get rid of throttle_vm_writeout	2016-10-07 18:46:27 -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	percpu: fix synchronization between synchronous map extension and chunk destruction	2016-05-25 11:48:25 -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/gup: Introduce get_user_pages_remote()	2016-02-16 10:04:09 +01:00
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	huge tmpfs: fix Committed_AS leak	2016-09-24 11:20:01 -07:00
slab_common.c	mm: charge/uncharge kmemcg from generic page allocator paths	2016-07-26 16:19:19 -07:00
slab.c	slab: Convert to hotplug state machine	2016-09-06 18:30:20 +02:00
slab.h	mm, kasan: switch SLUB to stackdepot, enable memory quarantine for SLUB	2016-07-28 16:07:41 -07:00
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_cgroup.c	mm: convert printk(KERN_<LEVEL> to pr_<level>	2016-03-17 15:09:34 -07:00
swap_state.c	mm: move most file-based accounting to the node	2016-07-28 16:07:41 -07:00
swap.c	mm, pagevec: release/reacquire lru_lock on pgdat change	2016-07-28 16:07:41 -07:00
swapfile.c	mm, swap: add swap_cluster_list	2016-10-07 18:46:27 -07:00
truncate.c	truncate: handle file thp	2016-07-26 16:19:19 -07:00
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	mm: move most file-based accounting to the node	2016-07-28 16:07:41 -07:00
vmacache.c	mm: unrig VMA cache hit ratio	2016-10-07 18:46:27 -07:00
vmalloc.c	mm/vmalloc.c: fix align value calculation error	2016-10-07 18:46:26 -07:00
vmpressure.c	mm/vmpressure.c: fix subtree pressure detection	2016-02-03 08:28:43 -08:00
vmscan.c	mm, vmscan: get rid of throttle_vm_writeout	2016-10-07 18:46:27 -07:00
vmstat.c	mm/page_owner: move page_owner specific function to page_owner.c	2016-10-07 18:46:27 -07:00
workingset.c	mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()	2016-09-30 15:26:52 -07:00
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