Messages in this thread Patch in this message | | | Date | Mon, 5 Apr 2010 16:23:34 +0200 | From | Oleg Nesterov <> | Subject | [PATCH -mm] oom: select_bad_process: never choose tasks with badness == 0 |
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This is the David's patch rediffed agains the recent changes in -mm.
As David pointed out, we should fix select_bad_process() which currently always selects the first process which was not filtered out before oom_badness(), no matter what oom_badness() returns.
Change the code to ignore the process if oom_badness() returns 0, this matters Documentation/filesystems/proc.txt and this merely looks better.
This also allows us to do more cleanups:
- no need to check OOM_SCORE_ADJ_MIN in select_bad_process(), oom_badness() returns 0 in this case.
- oom_badness() can simply return 0 instead of -1 if the task has no ->mm.
Now we can make it "unsigned" again, the signness and the special "points >= 0" in select_bad_process() was added to preserve the current behaviour.
Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> ---
include/linux/oom.h | 3 ++- mm/oom_kill.c | 11 ++++------- 2 files changed, 6 insertions(+), 8 deletions(-)
--- MM/include/linux/oom.h~5_BADNESS_DONT_RET_NEGATIVE 2010-04-05 15:39:21.000000000 +0200 +++ MM/include/linux/oom.h 2010-04-05 15:44:49.000000000 +0200 @@ -40,7 +40,8 @@ enum oom_constraint { CONSTRAINT_MEMORY_POLICY, }; -extern int oom_badness(struct task_struct *p, unsigned long totalpages); +extern unsigned int oom_badness(struct task_struct *p, + unsigned long totalpages); extern int try_set_zone_oom(struct zonelist *zonelist, gfp_t gfp_flags); extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags); --- MM/mm/oom_kill.c~5_BADNESS_DONT_RET_NEGATIVE 2010-04-05 15:39:21.000000000 +0200 +++ MM/mm/oom_kill.c 2010-04-05 16:09:58.000000000 +0200 @@ -153,7 +153,7 @@ static unsigned long oom_forkbomb_penalt * predictable as possible. The goal is to return the highest value for the * task consuming the most memory to avoid subsequent oom conditions. */ -int oom_badness(struct task_struct *p, unsigned long totalpages) +unsigned int oom_badness(struct task_struct *p, unsigned long totalpages) { int points; @@ -173,7 +173,7 @@ int oom_badness(struct task_struct *p, u p = find_lock_task_mm(p); if (!p) - return -1; + return 0; /* * The baseline for the badness score is the proportion of RAM that each * task's rss and swap space use. @@ -294,7 +294,7 @@ static struct task_struct *select_bad_pr *ppoints = 0; for_each_process(p) { - int points; + unsigned int points; /* skip the init task and kthreads */ if (is_global_init(p) || (p->flags & PF_KTHREAD)) @@ -336,11 +336,8 @@ static struct task_struct *select_bad_pr *ppoints = 1000; } - if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) - continue; - points = oom_badness(p, totalpages); - if (points >= 0 && (points > *ppoints || !chosen)) { + if (points > *ppoints) { chosen = p; *ppoints = points; }
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