Mel Gorman 04fa5d6a65 mm: migrate: check page_count of THP before migrating ... Hugh Dickins pointed out that migrate_misplaced_transhuge_page() does not check page_count before migrating like base page migration and khugepage. He could not see why this was safe and he is right. The potential impact of the bug is avoided due to the limitations of NUMA balancing. The page_mapcount() check ensures that only a single address space is using this page and as THPs are typically private it should not be possible for another address space to fault it in parallel. If the address space has one associated task then it's difficult to have both a GUP pin and be referencing the page at the same time. If there are multiple tasks then a buggy scenario requires that another thread be accessing the page while the direct IO is in flight. This is dodgy behaviour as there is a possibility of corruption with or without THP migration. It would be While we happen to be safe for the most part it is shoddy to depend on such "safety" so this patch checks the page count similar to anonymous pages. Note that this does not mean that the page_mapcount() check can go away. If we were to remove the page_mapcount() check the the THP would have to be unmapped from all referencing PTEs, replaced with migration PTEs and restored properly afterwards. Signed-off-by: Mel Gorman <mgorman@suse.de> Reported-by: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2013-01-11 14:54:54 -08:00
..
backing-dev.c	Revert "bdi: add a user-tunable cpu_list for the bdi flusher threads"	2012-12-17 11:29:09 -08:00
balloon_compaction.c	mm: introduce a common interface for balloon pages mobility	2012-12-11 17:22:26 -08:00
bootmem.c	mm/bootmem.c: remove unused wrapper function reserve_bootmem_generic()	2012-12-12 17:38:35 -08:00
bounce.c	bounce: allow use of bounce pool via config option	2012-07-18 16:40:35 -04:00
cleancache.c	->encode_fh() API change	2012-05-29 23:28:33 -04:00
compaction.c	compaction: fix build error in CMA && !COMPACTION	2012-12-20 17:40:18 -08:00
debug-pagealloc.c	mm, x86: Remove debug_pagealloc_enabled	2011-12-06 09:24:07 +01:00
dmapool.c	dmapool: make DMAPOOL_DEBUG detect corruption of free marker	2012-12-11 17:22:24 -08:00
fadvise.c	switch simple cases of fget_light to fdget	2012-09-26 22:20:08 -04:00
failslab.c	switch debugfs to umode_t	2012-01-03 22:54:56 -05:00
filemap_xip.c	mm: move all mmu notifier invocations to be done outside the PT lock	2012-10-09 16:22:58 +09:00
filemap.c	readahead: fault retry breaks mmap file read random detection	2012-10-09 16:22:47 +09:00
fremap.c	remap_file_pages: correctly handle the case of a NULL vm_ops pointer	2012-10-19 13:37:57 -07:00
frontswap.c	frontswap: support exclusive gets if tmem backend is capable	2012-09-21 10:38:12 -04:00
highmem.c	Some nice cleanups, and even a patch my wife did as a "live" demo for	2012-12-20 08:37:05 -08:00
huge_memory.c	mm: clean up transparent hugepage sysfs error messages	2012-12-20 17:40:20 -08:00
hugetlb_cgroup.c	mm/hugetlb: create hugetlb cgroup file in hugetlb_init	2012-12-18 15:02:15 -08:00
hugetlb.c	mm/hugetlb: create hugetlb cgroup file in hugetlb_init	2012-12-18 15:02:15 -08:00
hwpoison-inject.c	memcg: rename config variables	2012-07-31 18:42:43 -07:00
init-mm.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
internal.h	Automatic NUMA Balancing V11	2012-12-16 15:18:08 -08:00
interval_tree.c	mm: add CONFIG_DEBUG_VM_RB build option	2012-10-09 16:22:42 +09:00
Kconfig	memory-hotplug: document and enable CONFIG_MOVABLE_NODE	2012-12-18 15:02:12 -08:00
Kconfig.debug	mm: more intensive memory corruption debugging	2012-01-10 16:30:42 -08:00
kmemcheck.c
kmemleak-test.c	kmemleak: remove memset by using kzalloc	2011-01-27 18:31:51 +00:00
kmemleak.c	mm/kmemleak.c: remove obsolete simple_strtoul	2012-12-18 15:02:15 -08:00
ksm.c	ksm: make rmap walks more scalable	2012-12-20 07:06:56 -08:00
maccess.c	mm: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
madvise.c	mm: prepare VM_DONTDUMP for using in drivers	2012-10-09 16:22:18 +09:00
Makefile	mm: introduce a common interface for balloon pages mobility	2012-12-11 17:22:26 -08:00
memblock.c	x86, mm: Trim memory in memblock to be page aligned	2012-10-24 11:52:21 -07:00
memcontrol.c	memcg: don't register hotcpu notifier from ->css_alloc()	2012-12-20 17:40:20 -08:00
memory_hotplug.c	mm/memory_hotplug.c: improve comments	2012-12-18 15:02:15 -08:00
memory-failure.c	Automatic NUMA Balancing V11	2012-12-16 15:18:08 -08:00
memory.c	mm: reinstante dropped pmd_trans_splitting() check	2013-01-09 08:36:54 -08:00
mempolicy.c	mm: mempolicy: Convert shared_policy mutex to spinlock	2013-01-02 17:32:13 -08:00
mempool.c	mempool: add @gfp_mask to mempool_create_node()	2012-06-25 11:53:47 +02:00
migrate.c	mm: migrate: check page_count of THP before migrating	2013-01-11 14:54:54 -08:00
mincore.c	mm: thp: fix pmd_bad() triggering in code paths holding mmap_sem read mode	2012-03-21 17:54:54 -07:00
mlock.c	mm, thp: fix mlock statistics	2012-10-09 16:23:03 +09:00
mm_init.c	mm: Map most files to use export.h instead of module.h	2011-10-31 09:20:12 -04:00
mmap.c	Automatic NUMA Balancing V11	2012-12-16 15:18:08 -08:00
mmu_context.c	mm, counters: remove task argument to sync_mm_rss() and __sync_task_rss_stat()	2012-03-21 17:54:59 -07:00
mmu_notifier.c	mm/mmu_notifier: allocate mmu_notifier in advance	2012-10-25 14:37:53 -07:00
mmzone.c	memcg: fix hotplugged memory zone oops	2012-11-16 14:33:04 -08:00
mprotect.c	mm/mprotect.c: coding-style cleanups	2012-12-18 15:02:15 -08:00
mremap.c	Automatic NUMA Balancing V11	2012-12-16 15:18:08 -08:00
msync.c
nobootmem.c	mm: introduce new field "managed_pages" to struct zone	2012-12-12 17:38:34 -08:00
nommu.c	mm: export a function to get vm committed memory	2012-11-15 15:41:22 -08:00
oom_kill.c	mm, oom: remove redundant sleep in pagefault oom handler	2012-12-12 17:38:34 -08:00
page_alloc.c	mm: fix zone_watermark_ok_safe() accounting of isolated pages	2013-01-04 16:11:46 -08:00
page_cgroup.c	memcontrol: use N_MEMORY instead N_HIGH_MEMORY	2012-12-12 17:38:32 -08:00
page_io.c	mm: add support for direct_IO to highmem pages	2012-07-31 18:42:47 -07:00
page_isolation.c	mm: fix zone_watermark_ok_safe() accounting of isolated pages	2013-01-04 16:11:46 -08:00
page-writeback.c	mm: fix calculation of dirtyable memory	2012-12-20 17:40:18 -08:00
pagewalk.c	thp: change split_huge_page_pmd() interface	2012-12-12 17:38:31 -08:00
percpu-km.c	percpu: clear memory allocated with the km allocator	2010-10-02 10:28:42 +03:00
percpu-vm.c	mm: fix kernel-doc warnings	2012-06-20 14:39:36 -07:00
percpu.c	mm, percpu: Make sure percpu_alloc early parameter has an argument	2012-12-02 06:23:04 -08:00
pgtable-generic.c	mm: Only flush the TLB when clearing an accessible pte	2012-12-11 14:28:34 +00:00
process_vm_access.c	aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector()	2012-05-31 17:49:32 -07:00
quicklist.c	mm: delete various needless include <linux/module.h>	2011-10-31 09:20:11 -04:00
readahead.c	switch simple cases of fget_light to fdget	2012-09-26 22:20:08 -04:00
rmap.c	Automatic NUMA Balancing V11	2012-12-16 15:18:08 -08:00
shmem.c	mempolicy: remove arg from mpol_parse_str, mpol_to_str	2013-01-02 09:27:10 -08:00
slab_common.c	slab: propagate tunable values	2012-12-18 15:02:14 -08:00
slab.c	memcg: add comments clarifying aspects of cache attribute propagation	2012-12-18 15:02:15 -08:00
slab.h	slab: propagate tunable values	2012-12-18 15:02:14 -08:00
slob.c	sl[au]b: always get the cache from its page in kmem_cache_free()	2012-12-18 15:02:14 -08:00
slub.c	slub: drop mutex before deleting sysfs entry	2012-12-18 15:02:15 -08:00
sparse-vmemmap.c	mm: delete various needless include <linux/module.h>	2011-10-31 09:20:11 -04:00
sparse.c	memory-hotplug, mm/sparse.c: clear the memory to store struct page	2012-12-11 17:22:23 -08:00
swap_state.c	mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages	2012-07-31 18:42:47 -07:00
swap.c	mm: remove vma arg from page_evictable	2012-10-09 16:22:55 +09:00
swapfile.c	mm, oom: fix race when specifying a thread as the oom origin	2012-12-11 17:22:27 -08:00
truncate.c	mm: drop vmtruncate	2012-12-20 18:46:29 -05:00
util.c	Merge branch 'master' into for-next	2012-10-28 19:29:19 +01:00
vmalloc.c	mm: use IS_ENABLED(CONFIG_NUMA) instead of NUMA_BUILD	2012-12-11 17:22:22 -08:00
vmscan.c	MM: vmscan: remove __devinit attribute.	2013-01-03 15:57:13 -08:00
vmstat.c	Automatic NUMA Balancing V11	2012-12-16 15:18:08 -08:00