Messages in this thread Patch in this message | | | Date | Wed, 8 Jul 2015 16:42:47 -0700 (PDT) | From | David Rientjes <> | Subject | [patch v3 3/3] mm, oom: do not panic for oom kills triggered from sysrq |
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Sysrq+f is used to kill a process either for debug or when the VM is otherwise unresponsive.
It is not intended to trigger a panic when no process may be killed.
Avoid panicking the system for sysrq+f when no processes are killed.
Suggested-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: David Rientjes <rientjes@google.com> --- v2: no change v3: fix title per Hillf
Documentation/sysrq.txt | 3 ++- mm/oom_kill.c | 7 +++++-- 2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt --- a/Documentation/sysrq.txt +++ b/Documentation/sysrq.txt @@ -75,7 +75,8 @@ On all - write a character to /proc/sysrq-trigger. e.g.: 'e' - Send a SIGTERM to all processes, except for init. -'f' - Will call oom_kill to kill a memory hog process. +'f' - Will call the oom killer to kill a memory hog process, but do not + panic if nothing can be killed. 'g' - Used by kgdb (kernel debugger) diff --git a/mm/oom_kill.c b/mm/oom_kill.c --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -607,6 +607,9 @@ void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint, if (constraint != CONSTRAINT_NONE) return; } + /* Do not panic for oom kills triggered by sysrq */ + if (oc->order == -1) + return; dump_header(oc, NULL, memcg); panic("Out of memory: %s panic_on_oom is enabled\n", sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide"); @@ -686,11 +689,11 @@ bool out_of_memory(struct oom_control *oc) p = select_bad_process(oc, &points, totalpages); /* Found nothing?!?! Either we hang forever, or we panic. */ - if (!p) { + if (!p && oc->order != -1) { dump_header(oc, NULL, NULL); panic("Out of memory and no killable processes...\n"); } - if (p != (void *)-1UL) { + if (p && p != (void *)-1UL) { oom_kill_process(oc, p, points, totalpages, NULL, "Out of memory"); killed = 1;
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