From 35451beecbd7c86ce3249d543594517a5fe9a0cd Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 21 Sep 2009 17:02:27 -0700 Subject: ksm: unmerge is an origin of OOMs 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 Acked-by: Izik Eidus Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/ksm.c | 2 ++ mm/oom_kill.c | 2 +- mm/swapfile.c | 4 ++-- 3 files changed, 5 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/ksm.c b/mm/ksm.c index e11e7a5ac84f..37cc37325094 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1557,7 +1557,9 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr, 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 --git a/mm/oom_kill.c b/mm/oom_kill.c index a7b2460e922b..da4c342f2641 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -79,7 +79,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) /* * 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 --git a/mm/swapfile.c b/mm/swapfile.c index 74f1102e8749..f1bf19daadc6 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1575,9 +1575,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) 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 */ -- cgit v1.2.3