The patch titled
oom: avoid unnecessary mm locking and scanning for OOM_DISABLE
has been added to the -mm tree. Its filename is
oom-avoid-unnecessary-mm-locking-and-scanning-for-oom_disable.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
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
cpusets-restructure-the-function-cpuset_update_task_memory_state.patch
cpusets-update-tasks-page-slab-spread-flags-in-time.patch
cpusetmm-update-tasks-mems_allowed-in-time.patch
cpusetmm-update-tasks-mems_allowed-in-time-fix.patch
cpusetmm-update-tasks-mems_allowed-in-time-cleanup.patch
page-allocator-use-a-pre-calculated-value-instead-of-num_online_nodes-in-fast-paths-do-not-override-definition-of-node_set_online-with-macro.patch
mm-setup_per_zone_inactive_ratio-do-not-call-for-int_sqrt-if-not-needed.patch
mm-setup_per_zone_inactive_ratio-fix-comment-and-make-it-__init.patch
page-allocator-warn-if-__gfp_nofail-is-used-for-a-large-allocation.patch
mm-pm-freezer-disable-oom-killer-when-tasks-are-frozen.patch
oom-move-oom_adj-value-from-task_struct-to-mm_struct.patch
oom-avoid-unnecessary-mm-locking-and-scanning-for-oom_disable.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
