The patch titled
ksm: unmerge is an origin of OOMs
has been added to the -mm tree. Its filename is
ksm-unmerge-is-an-origin-of-ooms.patch
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------------------------------------------------------
Subject: ksm: unmerge is an origin of OOMs
From: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Just as the swapoff system call allocates many pages of RAM to various
processes, perhaps triggering OOM, so "echo 2 >/sys/kernel/mm/ksm/run"
(unmerge) is liable to allocate many pages of RAM to various processes,
perhaps triggering OOM; and each is normally run from a modest admin
process (swapoff or shell), easily repeated until it succeeds.
So treat unmerge_and_remove_all_rmap_items() in the same way that we treat
try_to_unuse(): generalize PF_SWAPOFF to PF_OOM_ORIGIN, and bracket both
with that, to ask the OOM killer to kill them first, to prevent them from
spawning more and more OOM kills.
Signed-off-by: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Acked-by: Izik Eidus <ieidus@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 2 +-
mm/ksm.c | 2 ++
mm/oom_kill.c | 2 +-
mm/swapfile.c | 4 ++--
4 files changed, 6 insertions(+), 4 deletions(-)
diff -puN include/linux/sched.h~ksm-unmerge-is-an-origin-of-ooms include/linux/sched.h
--- a/include/linux/sched.h~ksm-unmerge-is-an-origin-of-ooms
+++ a/include/linux/sched.h
@@ -1723,7 +1723,7 @@ extern cputime_t task_gtime(struct task_
#define PF_FROZEN 0x00010000 /* frozen for system suspend */
#define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */
#define PF_KSWAPD 0x00040000 /* I am kswapd */
-#define PF_SWAPOFF 0x00080000 /* I am in swapoff */
+#define PF_OOM_ORIGIN 0x00080000 /* Allocating much memory to others */
#define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */
#define PF_KTHREAD 0x00200000 /* I am a kernel thread */
#define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */
diff -puN mm/ksm.c~ksm-unmerge-is-an-origin-of-ooms mm/ksm.c
--- a/mm/ksm.c~ksm-unmerge-is-an-origin-of-ooms
+++ a/mm/ksm.c
@@ -1564,7 +1564,9 @@ static ssize_t run_store(struct kobject
if (ksm_run != flags) {
ksm_run = flags;
if (flags & KSM_RUN_UNMERGE) {
+ current->flags |= PF_OOM_ORIGIN;
err = unmerge_and_remove_all_rmap_items();
+ current->flags &= ~PF_OOM_ORIGIN;
if (err) {
ksm_run = KSM_RUN_STOP;
count = err;
diff -puN mm/oom_kill.c~ksm-unmerge-is-an-origin-of-ooms mm/oom_kill.c
--- a/mm/oom_kill.c~ksm-unmerge-is-an-origin-of-ooms
+++ a/mm/oom_kill.c
@@ -79,7 +79,7 @@ unsigned long badness(struct task_struct
/*
* swapoff can easily use up all memory, so kill those first.
*/
- if (p->flags & PF_SWAPOFF)
+ if (p->flags & PF_OOM_ORIGIN)
return ULONG_MAX;
/*
diff -puN mm/swapfile.c~ksm-unmerge-is-an-origin-of-ooms mm/swapfile.c
--- a/mm/swapfile.c~ksm-unmerge-is-an-origin-of-ooms
+++ a/mm/swapfile.c
@@ -1573,9 +1573,9 @@ SYSCALL_DEFINE1(swapoff, const char __us
p->flags &= ~SWP_WRITEOK;
spin_unlock(&swap_lock);
- current->flags |= PF_SWAPOFF;
+ current->flags |= PF_OOM_ORIGIN;
err = try_to_unuse(type);
- current->flags &= ~PF_SWAPOFF;
+ current->flags &= ~PF_OOM_ORIGIN;
if (err) {
/* re-insert swap space back into swap_list */
_
Patches currently in -mm which might be from hugh.dickins@xxxxxxxxxxxxx are
linux-next.patch
acpi-fix-null-bug-for-hid-uid-string-2.patch
vfs-optimize-touch_time-too-fix.patch
fs-new-truncate-helpers.patch
fs-use-new-truncate-helpers.patch
fs-introduce-new-truncate-sequence.patch
fs-convert-simple-fs-to-new-truncate.patch
tmpfs-convert-to-use-the-new-truncate-convention.patch
ext2-convert-to-use-the-new-truncate-convention.patch
fat-convert-to-use-the-new-truncate-convention.patch
btrfs-convert-to-use-the-new-truncate-convention.patch
jfs-convert-to-use-the-new-truncate-convention.patch
udf-convert-to-use-the-new-truncate-convention.patch
minix-convert-to-use-the-new-truncate-convention.patch
mm-oom-analysis-add-shmem-vmstat.patch
ksm-add-mmu_notifier-set_pte_at_notify.patch
ksm-first-tidy-up-madvise_vma.patch
ksm-define-madv_mergeable-and-madv_unmergeable.patch
ksm-the-mm-interface-to-ksm.patch
ksm-no-debug-in-page_dup_rmap.patch
ksm-identify-pageksm-pages.patch
ksm-kernel-samepage-merging.patch
ksm-prevent-mremap-move-poisoning.patch
ksm-change-copyright-message.patch
ksm-change-ksm-nice-level-to-be-5.patch
ksm-rename-kernel_pages_allocated.patch
ksm-move-pages_sharing-updates.patch
ksm-pages_unshared-and-pages_volatile.patch
ksm-break-cow-once-unshared.patch
ksm-keep-quiet-while-list-empty.patch
ksm-five-little-cleanups.patch
ksm-fix-endless-loop-on-oom.patch
ksm-distribute-remove_mm_from_lists.patch
ksm-fix-oom-deadlock.patch
ksm-fix-deadlock-with-munlock-in-exit_mmap.patch
ksm-sysfs-and-defaults.patch
ksm-add-some-documentation.patch
ksm-remove-vm_mergeable_flags.patch
ksm-clean-up-obsolete-references.patch
ksm-unmerge-is-an-origin-of-ooms.patch
ksm-mremap-use-err-from-ksm_madvise.patch
mm-add_to_swap_cache-must-not-sleep.patch
mm-add_to_swap_cache-does-not-return-eexist.patch
mm-includecheck-fix-for-mm-shmemc.patch
mm-introduce-page_lru_base_type-fix.patch
mm-replace-various-uses-of-num_physpages-by-totalram_pages.patch
hugetlbfs-allow-the-creation-of-files-suitable-for-map_private-on-the-vfs-internal-mount.patch
hugetlb-add-map_hugetlb-for-mmaping-pseudo-anonymous-huge-page-regions.patch
hugetlb-add-map_hugetlb-example.patch
getrusage-fill-ru_maxrss-value.patch
getrusage-fill-ru_maxrss-value-update.patch
ramfs-move-ramfs_magic-to-include-linux-magich.patch
memory-controller-soft-limit-organize-cgroups-v9-fix.patch
prio_tree-debugging-patch.patch
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