The patch titled
memcg: handle panic_on_oom=always case
has been added to the -mm tree. Its filename is
memcg-handle-panic_on_oom=always-case-v2.patch
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------------------------------------------------------
Subject: memcg: handle panic_on_oom=always case
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Presently, if panic_on_oom=2, the whole system panics even if the oom
happend in some special situation (as cpuset, mempolicy....). Then,
panic_on_oom=2 means painc_on_oom_always.
Now, memcg doesn't check panic_on_oom flag. This patch adds a check.
BTW, how it's useful ?
kdump+panic_on_oom=2 is the last tool to investigate what happens in
oom-ed system. When a task is killed, the sysytem recovers and there will
be few hint to know what happnes. In mission critical system, oom should
never happen. Then, panic_on_oom=2+kdump is useful to avoid next OOM by
knowing precise information via snapshot.
TODO:
- For memcg, it's for isolate system's memory usage, oom-notiifer and
freeze_at_oom (or rest_at_oom) should be implemented. Then, management
daemon can do similar jobs (as kdump) or taking snapshot per cgroup.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Reviewed-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/cgroups/memory.txt | 5 ++++-
Documentation/sysctl/vm.txt | 5 ++++-
mm/oom_kill.c | 2 ++
3 files changed, 10 insertions(+), 2 deletions(-)
diff -puN Documentation/cgroups/memory.txt~memcg-handle-panic_on_oom=always-case-v2 Documentation/cgroups/memory.txt
--- a/Documentation/cgroups/memory.txt~memcg-handle-panic_on_oom=always-case-v2
+++ a/Documentation/cgroups/memory.txt
@@ -182,6 +182,8 @@ list.
NOTE: Reclaim does not work for the root cgroup, since we cannot set any
limits on the root cgroup.
+Note2: When panic_on_oom is set to "2", the whole system will panic.
+
2. Locking
The memory controller uses the following hierarchy
@@ -379,7 +381,8 @@ The feature can be disabled by
NOTE1: Enabling/disabling will fail if the cgroup already has other
cgroups created below it.
-NOTE2: This feature can be enabled/disabled per subtree.
+NOTE2: When panic_on_oom is set to "2", the whole system will panic in
+case of an oom event in any cgroup.
7. Soft limits
diff -puN Documentation/sysctl/vm.txt~memcg-handle-panic_on_oom=always-case-v2 Documentation/sysctl/vm.txt
--- a/Documentation/sysctl/vm.txt~memcg-handle-panic_on_oom=always-case-v2
+++ a/Documentation/sysctl/vm.txt
@@ -573,11 +573,14 @@ Because other nodes' memory may be free.
may be not fatal yet.
If this is set to 2, the kernel panics compulsorily even on the
-above-mentioned.
+above-mentioned. Even oom happens under memory cgroup, the whole
+system panics.
The default value is 0.
1 and 2 are for failover of clustering. Please select either
according to your policy of failover.
+panic_on_oom=2+kdump gives you very strong tool to investigate
+why oom happens. You can get snapshot.
=============================================================
diff -puN mm/oom_kill.c~memcg-handle-panic_on_oom=always-case-v2 mm/oom_kill.c
--- a/mm/oom_kill.c~memcg-handle-panic_on_oom=always-case-v2
+++ a/mm/oom_kill.c
@@ -473,6 +473,8 @@ void mem_cgroup_out_of_memory(struct mem
unsigned long points = 0;
struct task_struct *p;
+ if (sysctl_panic_on_oom == 2)
+ panic("out of memory(memcg). panic_on_oom is selected.\n");
read_lock(&tasklist_lock);
retry:
p = select_bad_process(&points, mem);
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
memcg-fix-oom-killing-a-child-process-in-an-other-cgroup.patch
linux-next.patch
vfs-introduce-fmode_neg_offset-for-allowing-negative-f_pos.patch
mm-clean-up-mm_counter.patch
mm-avoid-false-sharing-of-mm_counter.patch
mm-avoid-false-sharing-of-mm_counter-checkpatch-fixes.patch
mm-count-swap-usage.patch
mm-count-swap-usage-checkpatch-fixes.patch
vmscan-get_scan_ratio-cleanup.patch
mm-restore-zone-all_unreclaimable-to-independence-word.patch
mm-restore-zone-all_unreclaimable-to-independence-word-fix.patch
mm-restore-zone-all_unreclaimable-to-independence-word-fix-2.patch
mm-migratec-kill-anon-local-variable-from-migrate_page_copy.patch
nodemaskh-remove-macro-any_online_node.patch
devmem-dont-allow-seek-to-last-page.patch
drivers-char-memc-cleanups.patch
drivers-char-memc-cleanups-fix.patch
drivers-char-memc-cleanups-fix-fix.patch
cgroup-introduce-cancel_attach.patch
cgroup-introduce-coalesce-css_get-and-css_put.patch
cgroups-revamp-subsys-array.patch
cgroups-subsystem-module-loading-interface.patch
cgroups-subsystem-module-loading-interface-fix.patch
cgroups-subsystem-module-unloading.patch
cgroups-net_cls-as-module.patch
cgroups-blkio-subsystem-as-module.patch
cgroups-clean-up-cgroup_pidlist_find-a-bit.patch
memcg-add-interface-to-move-charge-at-task-migration.patch
memcg-move-charges-of-anonymous-page.patch
memcg-move-charges-of-anonymous-page-cleanup.patch
memcg-improve-performance-in-moving-charge.patch
memcg-avoid-oom-during-moving-charge.patch
memcg-move-charges-of-anonymous-swap.patch
memcg-move-charges-of-anonymous-swap-fix.patch
memcg-improve-performance-in-moving-swap-charge.patch
memcg-improve-performance-in-moving-swap-charge-fix.patch
cgroup-implement-eventfd-based-generic-api-for-notifications.patch
cgroup-implement-eventfd-based-generic-api-for-notifications-kconfig-fix.patch
cgroup-implement-eventfd-based-generic-api-for-notifications-fixes.patch
memcg-extract-mem_group_usage-from-mem_cgroup_read.patch
memcg-rework-usage-of-stats-by-soft-limit.patch
memcg-implement-memory-thresholds.patch
memcg-implement-memory-thresholds-checkpatch-fixes.patch
memcg-implement-memory-thresholds-checkpatch-fixes-fix.patch
memcg-implement-memory-thresholds-check-if-first-threshold-crossed.patch
memcg-typo-in-comment-to-mem_cgroup_print_oom_info.patch
memcg-use-generic-percpu-instead-of-private-implementation.patch
memcg-update-threshold-and-softlimit-at-commit-v2.patch
memcg-share-event-counter-rather-than-duplicate-v2.patch
memcg-update-memcg_testtxt.patch
memcg-handle-panic_on_oom=always-case-v2.patch
sysctl-clean-up-vm-related-variable-declarations.patch
sysctl-clean-up-vm-related-variable-declarations-fix.patch
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