The patch titled oom: avoid unnecessary mm locking and scanning for OOM_DISABLE has been removed from the -mm tree. Its filename was oom-avoid-unnecessary-mm-locking-and-scanning-for-oom_disable.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: oom: avoid unnecessary mm locking and scanning for OOM_DISABLE From: David Rientjes <rientjes@xxxxxxxxxx> This moves the check for OOM_DISABLE to the badness heuristic so it is only necessary to hold task_lock() once. If the mm is OOM_DISABLE, the score is 0, which is also correctly exported via /proc/pid/oom_score. This requires that tasks with badness scores of 0 are prohibited from being oom killed, which makes sense since they would not allow for future memory freeing anyway. Since the oom_adj value is a characteristic of an mm and not a task, it is no longer necessary to check the oom_adj value for threads sharing the same memory (except when simply issuing SIGKILLs for threads in other thread groups). Cc: Nick Piggin <npiggin@xxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Mel Gorman <mel@xxxxxxxxx> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/oom_kill.c | 42 ++++++++++-------------------------------- 1 file changed, 10 insertions(+), 32 deletions(-) diff -puN mm/oom_kill.c~oom-avoid-unnecessary-mm-locking-and-scanning-for-oom_disable mm/oom_kill.c --- a/mm/oom_kill.c~oom-avoid-unnecessary-mm-locking-and-scanning-for-oom_disable +++ a/mm/oom_kill.c @@ -67,6 +67,10 @@ unsigned long badness(struct task_struct return 0; } oom_adj = mm->oom_adj; + if (oom_adj == OOM_DISABLE) { + task_unlock(p); + return 0; + } /* * The memory size of the process is the basis for the badness. @@ -253,15 +257,8 @@ static struct task_struct *select_bad_pr *ppoints = ULONG_MAX; } - task_lock(p); - if (p->mm && p->mm->oom_adj == OOM_DISABLE) { - task_unlock(p); - continue; - } - task_unlock(p); - points = badness(p, uptime.tv_sec); - if (points > *ppoints || !chosen) { + if (points > *ppoints) { chosen = p; *ppoints = points; } @@ -354,32 +351,13 @@ static int oom_kill_task(struct task_str struct mm_struct *mm; struct task_struct *g, *q; + task_lock(p); mm = p->mm; - - /* WARNING: mm may not be dereferenced since we did not obtain its - * value from get_task_mm(p). This is OK since all we need to do is - * compare mm to q->mm below. - * - * Furthermore, even if mm contains a non-NULL value, p->mm may - * change to NULL at any time since we do not hold task_lock(p). - * However, this is of no concern to us. - */ - - if (mm == NULL) + if (!mm || mm->oom_adj == OOM_DISABLE) { + task_unlock(p); return 1; - - /* - * Don't kill the process if any threads are set to OOM_DISABLE - */ - do_each_thread(g, q) { - task_lock(q); - if (q->mm == mm && q->mm && q->mm->oom_adj == OOM_DISABLE) { - task_unlock(q); - return 1; - } - task_unlock(q); - } while_each_thread(g, q); - + } + task_unlock(p); __oom_kill_task(p, 1); /* _ Patches currently in -mm which might be from rientjes@xxxxxxxxxx are origin.patch linux-next.patch oom-move-oom_adj-value-from-task_struct-to-mm_struct-fix.patch memcg-add-file-based-rss-accounting.patch memcg-add-file-based-rss-accounting-fix-mem_cgroup_update_mapped_file_stat-oops.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html