mm/oom_kill.c: clean up oom_reap_task_mm() (431f42fd) · Commits · 戴 / test

Andrew has noticed some inconsistencies in oom_reap_task_mm. Notably - Undocumented return value. - comment "failed to reap part..." is misleading - sounds like it's referring to something which happened in the past, is in fact referring to something which might happen in the future. - fails to call trace_finish_task_reaping() in one case - code duplication. - Increases mmap_sem hold time a little by moving trace_finish_task_reaping() inside the locked region. So sue me ;) - Sharing the finish: path means that the trace event won't distinguish between the two sources of finishing. Add a short explanation for the return value and fix the rest by reorganizing the function a bit to have unified function exit paths. Link: http://lkml.kernel.org/r/20180724141747.GP28386@dhcp22.suse.cz Suggested-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Michal Hocko <mhocko@suse.com> Reviewed-by:

Andrew Morton <akpm@linux-foundation.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/oom_kill.c

+16 −8

Original line number	Diff line number	Diff line
		@@ -534,8 +534,16 @@ bool __oom_reap_task_mm(struct mm_struct *mm)
		return ret;
		}

		/*
		* Reaps the address space of the give task.
		*
		* Returns true on success and false if none or part of the address space
		* has been reclaimed and the caller should retry later.
		*/
		static bool oom_reap_task_mm(struct task_struct tsk, struct mm_struct mm)
		{
		bool ret = true;

		if (!down_read_trylock(&mm->mmap_sem)) {
		trace_skip_task_reaping(tsk->pid);
		return false;
		@@ -548,28 +556,28 @@ static bool oom_reap_task_mm(struct task_struct tsk, struct mm_struct mm)
		* down_write();up_write() cycle in exit_mmap().
		*/
		if (test_bit(MMF_OOM_SKIP, &mm->flags)) {
		up_read(&mm->mmap_sem);
		trace_skip_task_reaping(tsk->pid);
		return true;
		goto out_unlock;
		}

		trace_start_task_reaping(tsk->pid);

		/* failed to reap part of the address space. Try again later */
		if (!__oom_reap_task_mm(mm)) {
		up_read(&mm->mmap_sem);
		return false;
		}
		ret = __oom_reap_task_mm(mm);
		if (!ret)
		goto out_finish;

		pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
		task_pid_nr(tsk), tsk->comm,
		K(get_mm_counter(mm, MM_ANONPAGES)),
		K(get_mm_counter(mm, MM_FILEPAGES)),
		K(get_mm_counter(mm, MM_SHMEMPAGES)));
		out_finish:
		trace_finish_task_reaping(tsk->pid);
		out_unlock:
		up_read(&mm->mmap_sem);

		trace_finish_task_reaping(tsk->pid);
		return true;
		return ret;
		}

		#define MAX_OOM_REAP_RETRIES 10

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