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77da2ba064
linux/mm
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Claudio Imbrenda 77da2ba064 mm/ksm: fix interaction with THP 
This patch fixes a corner case for KSM.  When two pages belong or
belonged to the same transparent hugepage, and they should be merged,
KSM fails to split the page, and therefore no merging happens.

This bug can be reproduced by:
* making sure ksm is running (in case disabling ksmtuned)
* enabling transparent hugepages
* allocating a THP-aligned 1-THP-sized buffer
  e.g. on amd64: posix_memalign(&p, 1<<21, 1<<21)
* filling it with the same values
  e.g. memset(p, 42, 1<<21)
* performing madvise to make it mergeable
  e.g. madvise(p, 1<<21, MADV_MERGEABLE)
* waiting for KSM to perform a few scans

The expected outcome is that the all the pages get merged (1 shared and
the rest sharing); the actual outcome is that no pages get merged (1
unshared and the rest volatile)

The reason of this behaviour is that we increase the reference count
once for both pages we want to merge, but if they belong to the same
hugepage (or compound page), the reference counter used in both cases is
the one of the head of the compound page.  This means that
split_huge_page will find a value of the reference counter too high and
will fail.

This patch solves this problem by testing if the two pages to merge
belong to the same hugepage when attempting to merge them.  If so, the
hugepage is split safely.  This means that the hugepage is not split if
not necessary.

Link: http://lkml.kernel.org/r/1521548069-24758-1-git-send-email-imbrenda@linux.vnet.ibm.com
Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Co-authored-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-05 21:36:27 -07:00
..
kasan slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
backing-dev.c mm: reuse DEFINE_SHOW_ATTRIBUTE() macro 2018-04-05 21:36:25 -07:00
balloon_compaction.c virtio_balloon: fix deadlock on OOM 2017-11-14 23:57:38 +02:00
bootmem.c mm: docs: fix parameter names mismatch 2018-02-06 18:32:48 -08:00
cleancache.c fs: switch ->s_uuid to uuid_t 2017-06-05 16:59:12 +02:00
cma_debug.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cma.c headers: untangle kmemleak.h from mm.h 2018-04-05 21:36:27 -07:00
cma.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compaction.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
debug_page_ref.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
debug.c mm/debug.c: provide useful debugging information for VM_BUG 2018-01-04 16:45:09 -08:00
dmapool.c lib/vsprintf.c: remove %Z support 2017-02-27 18:43:47 -08:00
early_ioremap.c mm/early_ioremap: Fix boot hang with earlyprintk=efi,keep 2017-12-11 14:54:44 +01:00
fadvise.c mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64() 2018-04-02 20:16:10 +02:00
failslab.c mm: make should_failslab always available for fault injection 2018-04-05 21:36:26 -07:00
filemap.c mm/filemap.c: remove include of hardirq.h 2018-01-31 17:18:36 -08:00
frame_vector.c mm/frame_vector.c: release a semaphore in 'get_vaddr_frames()' 2017-12-14 16:00:48 -08:00
frontswap.c mm, frontswap: convert frontswap_enabled to static key 2016-07-26 16:19:19 -07:00
gup_benchmark.c mm: add infrastructure for get_user_pages_fast() benchmarking 2017-11-17 16:10:04 -08:00
gup.c mm/gup.c: fix coding style issues. 2018-04-05 21:36:26 -07:00
highmem.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hmm.c libnvdimm for 4.16 2018-02-06 10:41:33 -08:00
huge_memory.c mm/huge_memory.c: reorder operations in __split_huge_page_tail() 2018-04-05 21:36:25 -07:00
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, hugetlbfs: introduce ->pagesize() to vm_operations_struct 2018-04-05 21:36:26 -07:00
hwpoison-inject.c mm/memory_failure: Remove unused trapno from memory_failure 2018-01-23 12:17:42 -06:00
init-mm.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
internal.h Revert "mm, thp: Do not make pmd/pud dirty without a reason" 2017-11-29 09:01:01 -08:00
interval_tree.c mm/interval_tree.c: use vma_pages() helper 2018-01-31 17:18:37 -08:00
Kconfig treewide: simplify Kconfig dependencies for removed archs 2018-03-26 15:55:57 +02:00
Kconfig.debug kmemcheck: rip it out 2017-11-15 18:21:05 -08:00
khugepaged.c mm, thp: do not cause memcg oom for thp 2018-03-22 17:07:02 -07:00
kmemleak-test.c
kmemleak.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
ksm.c mm/ksm: fix interaction with THP 2018-04-05 21:36:27 -07:00
list_lru.c mm: make counting of list_lru_one::nr_items lockless 2018-04-05 21:36:27 -07:00
maccess.c mm: docs: fix parameter names mismatch 2018-02-06 18:32:48 -08:00
madvise.c mm/memory_failure: Remove unused trapno from memory_failure 2018-01-23 12:17:42 -06:00
Makefile mm/swap_slots.c: use conditional compilation 2018-04-05 21:36:24 -07:00
memblock.c mm/memblock.c: cast constant ULLONG_MAX to phys_addr_t 2018-04-05 21:36:27 -07:00
memcontrol.c mm/memcontrol.c: fix parameter description mismatch 2018-03-28 13:42:05 -10:00
memory_hotplug.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
memory-failure.c mm: hwpoison: disable memory error handling on 1GB hugepage 2018-04-05 21:36:25 -07:00
memory.c mm: swap: unify cluster-based and vma-based swap readahead 2018-04-05 21:36:25 -07:00
mempolicy.c Merge branch 'syscalls-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux 2018-04-02 21:22:12 -07:00
mempool.c kasan: detect invalid frees for large mempool objects 2018-02-06 18:32:43 -08:00
memtest.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
migrate.c mm: add kernel_move_pages() helper, move compat syscall to mm/migrate.c 2018-04-02 20:15:32 +02:00
mincore.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mlock.c mm, mlock, vmscan: no more skipping pagevecs 2018-02-21 15:35:42 -08:00
mm_init.c
mmap.c mm: always print RLIMIT_DATA warning 2018-04-05 21:36:24 -07:00
mmu_context.c sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
mmu_notifier.c mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks 2018-01-31 17:18:38 -08:00
mmzone.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mprotect.c mm: Clear arch specific VM flags on protection change 2018-03-18 07:38:47 -07:00
mremap.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
msync.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nobootmem.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nommu.c mm/nommu: remove description of alloc_vm_area 2018-04-05 21:36:26 -07:00
oom_kill.c mm, oom: remove 3% bonus for CAP_SYS_ADMIN processes 2018-04-05 21:36:27 -07:00
page_alloc.c mm/page_isolation.c: make start_isolate_page_range() fail if already isolated 2018-04-05 21:36:27 -07:00
page_counter.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
page_ext.c mm/page_ext.c: make page_ext_init a noop when CONFIG_PAGE_EXTENSION but nothing uses it 2018-01-31 17:18:39 -08:00
page_idle.c mm: thp: fix potential clearing to referenced flag in page_idle_clear_pte_refs_one() 2018-04-05 21:36:25 -07:00
page_io.c block: convert to bio_first_bvec_all & bio_first_page_all 2018-01-06 09:18:00 -07:00
page_isolation.c mm/page_isolation.c: make start_isolate_page_range() fail if already isolated 2018-04-05 21:36:27 -07:00
page_owner.c mm/page_owner.c: make early_page_owner_param() __init 2018-04-05 21:36:26 -07:00
page_poison.c mm/page_poison.c: make early_page_poison_param() __init 2018-04-05 21:36:26 -07:00
page_vma_mapped.c mm, page_vma_mapped: Introduce pfn_in_hpage() 2018-01-22 12:15:57 -08:00
page-writeback.c Revert "mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical" 2017-11-29 18:40:43 -08:00
pagewalk.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
percpu-internal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
percpu-km.c percpu: allow select gfp to be passed to underlying allocators 2018-02-18 05:33:01 -08:00
percpu-stats.c mm: reuse DEFINE_SHOW_ATTRIBUTE() macro 2018-04-05 21:36:25 -07:00
percpu-vm.c percpu: allow select gfp to be passed to underlying allocators 2018-02-18 05:33:01 -08:00
percpu.c arch: remove obsolete architecture ports 2018-04-02 20:20:12 -07:00
pgtable-generic.c mm: do not lose dirty and accessed bits in pmdp_invalidate() 2018-01-31 17:18:38 -08:00
process_vm_access.c mm: docs: add blank lines to silence sphinx "Unexpected indentation" errors 2018-02-06 18:32:48 -08:00
quicklist.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
readahead.c mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead() 2018-04-02 20:16:12 +02:00
rmap.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
rodata_test.c mm: fix RODATA_TEST failure "rodata_test: test data was not read only" 2017-10-03 17:54:24 -07:00
shmem.c mm: swap: unify cluster-based and vma-based swap readahead 2018-04-05 21:36:25 -07:00
slab_common.c mm: make should_failslab always available for fault injection 2018-04-05 21:36:26 -07:00
slab.c slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
slab.h slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
slob.c slab, slub, slob: add slab_flags_t 2017-11-15 18:21:01 -08:00
slub.c slab, slub: skip unnecessary kasan_cache_shutdown() 2018-04-05 21:36:24 -07:00
sparse-vmemmap.c mm: merge vmem_altmap_alloc into altmap_alloc_block_buf 2018-01-08 11:46:23 -08:00
sparse.c mm/memory_hotplug: optimize memory hotplug 2018-04-05 21:36:25 -07:00
swap_cgroup.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
swap_slots.c mm/swap_slots.c: use conditional compilation 2018-04-05 21:36:24 -07:00
swap_state.c mm/swap_state.c: make bool enable_vma_readahead and swap_vma_readahead() static 2018-04-05 21:36:27 -07:00
swap.c mm/swap.c: remove @cold parameter description for release_pages() 2018-04-05 21:36:26 -07:00
swapfile.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
truncate.c mm: add unmap_mapping_pages() 2018-01-31 17:18:37 -08:00
usercopy.c usercopy: WARN() on slab cache usercopy region violations 2018-01-15 12:07:48 -08:00
userfaultfd.c mm/userfaultfd.c: remove duplicate include 2018-02-06 18:32:47 -08:00
util.c mm: fix races between swapoff and flush dcache 2018-04-05 21:36:26 -07:00
vmacache.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vmalloc.c vmalloc: fix __GFP_HIGHMEM usage for vmalloc_32 on 32b systems 2018-02-21 15:35:43 -08:00
vmpressure.c mm, vmpressure: pass-through notification support 2017-07-10 16:32:31 -07:00
vmscan.c mm, page_alloc: wakeup kcompactd even if kswapd cannot free more memory 2018-04-05 21:36:27 -07:00
vmstat.c mm/vmstat.c: fix vmstat_update() preemption BUG 2018-03-28 13:42:05 -10:00
workingset.c mm, truncate: do not check mapping for every page being truncated 2017-11-15 18:21:06 -08:00
z3fold.c z3fold: limit use of stale list for allocation 2018-04-05 21:36:25 -07:00
zbud.c mm: docs: fix parameter names mismatch 2018-02-06 18:32:48 -08:00
zpool.c mm/zpool.c: zpool_evictable: fix mismatch in parameter name and kernel-doc 2018-02-21 15:35:43 -08:00
zsmalloc.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
zswap.c mm, swap, frontswap: fix THP swap if frontswap enabled 2018-02-21 15:35:43 -08:00