Subject: + mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch added to -mm tree
To: rientjes@xxxxxxxxxx,hannes@xxxxxxxxxxx,kamezawa.hiroyu@xxxxxxxxxxxxxx,mhocko@xxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 18 Nov 2013 13:42:45 -0800
The patch titled
Subject: mm, memcg: avoid oom notification when current needs access to memory reserves
has been added to the -mm tree. Its filename is
mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch
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From: David Rientjes <rientjes@xxxxxxxxxx>
Subject: mm, memcg: avoid oom notification when current needs access to memory reserves
When current has a pending SIGKILL or is already in the exit path, it only
needs access to memory reserves to fully exit. In that sense, the memcg
is not actually oom for current, it simply needs to bypass memory charges
to exit and free its memory, which is guarantee itself that memory will be
freed.
We only want to notify userspace for actionable oom conditions where
something needs to be done (and all oom handling can already be deferred
to userspace through this method by disabling the memcg oom killer with
memory.oom_control), not simply when a memcg has reached its limit, which
would actually have to happen before memcg reclaim actually frees memory
for charges.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Reported-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff -puN mm/memcontrol.c~mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves
+++ a/mm/memcontrol.c
@@ -1783,16 +1783,6 @@ static void mem_cgroup_out_of_memory(str
unsigned int points = 0;
struct task_struct *chosen = NULL;
- /*
- * If current has a pending SIGKILL or is exiting, then automatically
- * select it. The goal is to allow it to allocate so that it may
- * quickly exit and free its memory.
- */
- if (fatal_signal_pending(current) || current->flags & PF_EXITING) {
- set_thread_flag(TIF_MEMDIE);
- return;
- }
-
check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1;
for_each_mem_cgroup_tree(iter, memcg) {
@@ -2243,6 +2233,16 @@ bool mem_cgroup_oom_synchronize(bool han
if (!handle)
goto cleanup;
+ /*
+ * If current has a pending SIGKILL or is exiting, then automatically
+ * select it. The goal is to allow it to allocate so that it may
+ * quickly exit and free its memory.
+ */
+ if (fatal_signal_pending(current) || current->flags & PF_EXITING) {
+ set_thread_flag(TIF_MEMDIE);
+ goto cleanup;
+ }
+
owait.memcg = memcg;
owait.wait.flags = 0;
owait.wait.func = memcg_oom_wake_function;
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
origin.patch
x86-srat-use-numa_no_node.patch
mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch
mm-memcg-add-memoryoom_control-notification-for-system-oom.patch
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