Both "child->mm == mm" and "p->mm != mm" checks in oom_kill_process() are wrong. ->mm can be if task is the exited group leader. This means in particular that "kill sharing same memory" loop can miss a process with a zombie leader which uses the same ->mm.
Note: the process_has_mm(child, p->mm) check is still not 100% correct, p->mm can be NULL too. This is minor, but probably deserves a fix or a comment anyway. Signed-off-by: Oleg Nesterov <[email protected]> --- mm/oom_kill.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 8e7bed2..8ecac2ef 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -483,6 +483,17 @@ void oom_killer_enable(void) oom_killer_disabled = false; } +static bool process_has_mm(struct task_struct *p, struct mm_struct *mm) +{ + struct task_struct *t; + + for_each_thread(p, t) + if (t->mm) + return t->mm == mm; + + return false; +} + #define K(x) ((x) << (PAGE_SHIFT-10)) /* * Must be called while holding a reference to p, which will be released upon @@ -530,7 +541,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, list_for_each_entry(child, &t->children, sibling) { unsigned int child_points; - if (child->mm == p->mm) + if (process_has_mm(child, p->mm)) continue; /* * oom_badness() returns 0 if the thread is unkillable @@ -588,7 +599,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, continue; if (same_thread_group(p, victim)) continue; - if (p->mm != mm) + if (!process_has_mm(p, mm)) continue; if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) continue; -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
