From: Yafang Shao <laoar.shao@xxxxxxxxx> Subject: mm/oom_kill.c: fix uninitialized oc->constraint In dump_oom_summary() oc->constraint is used to show oom_constraint_text, but it hasn't been set before. So the value of it is always the default value 0. We should inititialize it before. Bellow is the output when memcg oom occurs, before this patch: [ 133.078102] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null), cpuset=/,mems_allowed=0,oom_memcg=/foo,task_memcg=/foo,task=bash,pid=7997,uid=0 after this patch: [ 952.977946] oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null), cpuset=/,mems_allowed=0,oom_memcg=/foo,task_memcg=/foo,task=bash,pid=13681,uid=0 Link: http://lkml.kernel.org/r/1560522038-15879-1-git-send-email-laoar.shao@xxxxxxxxx Fixes: ef8444ea01d7 ("mm, oom: reorganize the oom report in dump_header") Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Wind Yu <yuzhoujian@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/oom_kill.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) --- a/mm/oom_kill.c~mm-oom_kill-fix-uninitialized-oc-constraint +++ a/mm/oom_kill.c @@ -987,8 +987,7 @@ static void oom_kill_process(struct oom_ /* * Determines whether the kernel must panic because of the panic_on_oom sysctl. */ -static void check_panic_on_oom(struct oom_control *oc, - enum oom_constraint constraint) +static void check_panic_on_oom(struct oom_control *oc) { if (likely(!sysctl_panic_on_oom)) return; @@ -998,7 +997,7 @@ static void check_panic_on_oom(struct oo * does not panic for cpuset, mempolicy, or memcg allocation * failures. */ - if (constraint != CONSTRAINT_NONE) + if (oc->constraint != CONSTRAINT_NONE) return; } /* Do not panic for oom kills triggered by sysrq */ @@ -1035,7 +1034,6 @@ EXPORT_SYMBOL_GPL(unregister_oom_notifie bool out_of_memory(struct oom_control *oc) { unsigned long freed = 0; - enum oom_constraint constraint = CONSTRAINT_NONE; if (oom_killer_disabled) return false; @@ -1071,10 +1069,10 @@ bool out_of_memory(struct oom_control *o * Check if there were limitations on the allocation (only relevant for * NUMA and memcg) that may require different handling. */ - constraint = constrained_alloc(oc); - if (constraint != CONSTRAINT_MEMORY_POLICY) + oc->constraint = constrained_alloc(oc); + if (oc->constraint != CONSTRAINT_MEMORY_POLICY) oc->nodemask = NULL; - check_panic_on_oom(oc, constraint); + check_panic_on_oom(oc); if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task && current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) && _
