If mm->mm_users is not incremented because it is already zero by the oom reaper, meaning the final refcount has been dropped, do not set MMF_OOM_SKIP prematurely. __mmput() may not have had a chance to do exit_mmap() yet, so memory from a previous oom victim is still mapped. __mput() naturally requires no references on mm->mm_users to do exit_mmap(). Without this, several processes can be oom killed unnecessarily and the oom log can show an abundance of memory available if exit_mmap() is in progress at the time the process is skipped. Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx> --- mm/oom_kill.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -531,6 +531,7 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) NULL); } tlb_finish_mmu(&tlb, 0, -1); + set_bit(MMF_OOM_SKIP, &mm->flags); pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n", task_pid_nr(tsk), tsk->comm, K(get_mm_counter(mm, MM_ANONPAGES)), @@ -562,7 +563,11 @@ static void oom_reap_task(struct task_struct *tsk) if (attempts <= MAX_OOM_REAP_RETRIES) goto done; - + /* + * Hide this mm from OOM killer because it cannot be reaped since + * mm->mmap_sem cannot be acquired. + */ + set_bit(MMF_OOM_SKIP, &mm->flags); pr_info("oom_reaper: unable to reap pid:%d (%s)\n", task_pid_nr(tsk), tsk->comm); debug_show_all_locks(); @@ -570,12 +575,6 @@ static void oom_reap_task(struct task_struct *tsk) done: tsk->oom_reaper_list = NULL; - /* - * Hide this mm from OOM killer because it has been either reaped or - * somebody can't call up_write(mmap_sem). - */ - set_bit(MMF_OOM_SKIP, &mm->flags); - /* Drop a reference taken by wake_oom_reaper */ put_task_struct(tsk); } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>