The patch titled oom: select_bad_process(): never choose tasks with badness == 0 has been added to the -mm tree. Its filename is oom-select_bad_process-never-choose-tasks-with-badness-==-0.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: oom: select_bad_process(): never choose tasks with badness == 0 From: Oleg Nesterov <oleg@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/oom.h | 3 ++- mm/oom_kill.c | 11 ++++------- 2 files changed, 6 insertions(+), 8 deletions(-) diff -puN include/linux/oom.h~oom-select_bad_process-never-choose-tasks-with-badness-==-0 include/linux/oom.h --- a/include/linux/oom.h~oom-select_bad_process-never-choose-tasks-with-badness-==-0 +++ a/include/linux/oom.h @@ -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); diff -puN mm/oom_kill.c~oom-select_bad_process-never-choose-tasks-with-badness-==-0 mm/oom_kill.c --- a/mm/oom_kill.c~oom-select_bad_process-never-choose-tasks-with-badness-==-0 +++ a/mm/oom_kill.c @@ -154,7 +154,7 @@ 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; @@ -174,7 +174,7 @@ 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. @@ -295,7 +295,7 @@ 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)) @@ -337,11 +337,8 @@ 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; } _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch linux-next.patch cpu-timers-simplify-rlimit_cpu-handling.patch cpu-timers-cleanup-arm_timer.patch cpu-timers-return-correct-previous-timer-reload-value.patch cpu-timers-change-sigev_none-timer-implementation.patch cpu-timers-assure-to-not-iterate-over-all-threads-in-fastpath_timer_check.patch cpu-timers-optimize-run_posix_cpu_timers.patch oom-select_bad_process-check-pf_kthread-instead-of-mm-to-skip-kthreads.patch oom-select_bad_process-pf_exiting-check-should-take-mm-into-account.patch oom-introduce-find_lock_task_mm-to-fix-mm-false-positives.patch oom-oom_forkbomb_penalty-move-thread_group_cputime-out-of-task_lock.patch oom-hold-tasklist_lock-when-dumping-tasks.patch oom-give-current-access-to-memory-reserves-if-it-has-been-killed.patch oom-avoid-sending-exiting-tasks-a-sigkill.patch oom-clean-up-oom_kill_task.patch oom-clean-up-oom_badness.patch oom-select_bad_process-never-choose-tasks-with-badness-==-0.patch kmod-add-init-function-to-usermodehelper.patch exec-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch umh-creds-convert-call_usermodehelper_keys-to-use-subprocess_info-init.patch umh-creds-kill-subprocess_info-cred-logic.patch call_usermodehelper-no-need-to-unblock-signals.patch wait_for_helper-sigchld-from-user-space-can-lead-to-use-after-free.patch call_usermodehelper-simplify-fix-umh_no_wait-case.patch call_usermodehelper-umh_wait_exec-ignores-kernel_thread-failure.patch coredump-factor-out-the-not-ispipe-file-checks.patch coredump-cleanup-ispipe-code.patch coredump-factor-out-put_cred-calls.patch coredump-shift-down_writemmap_sem-into-coredump_wait.patch exit-exit_notify-can-trust-signal-notify_count-0.patch exit-change-zap_other_threads-to-count-sub-threads.patch exit-avoid-sig-count-in-de_thread-__exit_signal-synchronization.patch exit-avoid-sig-count-in-__exit_signal-to-detect-the-group-dead-case.patch posix-cpu-timers-avoid-task-signal-=-null-checks.patch ia64-ptrace_attach_sync_user_rbs-avoid-task-signal-=-null-checks.patch fork-exit-move-tty_kref_put-outside-of-__cleanup_signal.patch signals-make-task_struct-signal-immutable-refcountable.patch signals-clear-signal-tty-when-the-last-thread-exits.patch signals-clear-signal-tty-when-the-last-thread-exits-fix.patch signals-kill-the-awful-task_rq_unlock_wait-hack.patch exit-__exit_signal-use-thread_group_leader-consistently.patch kill-the-obsolete-thread_group_cputime_free-and-taskstats_tgid_init-helpers.patch exit-move-taskstats_tgid_free-from-__exit_signal-to-free_signal_struct.patch check_unshare_flags-kill-the-bogus-clone_sighand-sig-count-check.patch proc-get_nr_threads-doesnt-need-siglock-any-longer.patch proc-make-collect_sigign_sigcatch-rcu-safe.patch proc-make-task_sig-lockless.patch proc_sched_show_task-use-get_nr_threads.patch keyctl_session_to_parent-use-thread_group_empty-to-check-singlethreadness.patch proc-turn-signal_struct-count-into-int-nr_threads.patch proc-turn-signal_struct-count-into-int-nr_threads-checkpatch-fixes.patch proc-cleanup-remove-unused-assignments.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html