linux-kernel - [RFC PATCH v2 1/7] mm, oom: refactor select_bad

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Message-ID: <1496342115-3974-2-git-send-email-guro@fb.com>
Date:   Thu, 1 Jun 2017 19:35:09 +0100
From:   Roman Gushchin <guro@...com>
To:     <linux-mm@...ck.org>
CC:     Roman Gushchin <guro@...com>, Tejun Heo <tj@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Li Zefan <lizefan@...wei.com>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        <kernel-team@...com>, <cgroups@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH v2 1/7] mm, oom: refactor select_bad_process() to take memcg as an argument

The select_bad_process() function will be used further
to select a process to kill in the victim cgroup.
This cgroup doesn't necessary match oc->memcg,
which is a cgroup, which limits were caused cgroup-wide OOM
(or NULL in case of global OOM).

So, refactor select_bad_process() to take a pointer to
a cgroup to iterate over as an argument.

Signed-off-by: Roman Gushchin <guro@...com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Li Zefan <lizefan@...wei.com>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Vladimir Davydov <vdavydov.dev@...il.com>
Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc: kernel-team@...com
Cc: cgroups@...r.kernel.org
Cc: linux-doc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org
---
 mm/oom_kill.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 04c9143..f8b0fb1 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -343,10 +343,11 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
  * Simple selection loop. We choose the process with the highest number of
  * 'points'. In case scan was aborted, oc->chosen is set to -1.
  */
-static void select_bad_process(struct oom_control *oc)
+static void select_bad_process(struct oom_control *oc,
+			       struct mem_cgroup *memcg)
 {
-	if (is_memcg_oom(oc))
-		mem_cgroup_scan_tasks(oc->memcg, oom_evaluate_task, oc);
+	if (memcg)
+		mem_cgroup_scan_tasks(memcg, oom_evaluate_task, oc);
 	else {
 		struct task_struct *p;
 
@@ -1032,7 +1033,7 @@ bool out_of_memory(struct oom_control *oc)
 		return true;
 	}
 
-	select_bad_process(oc);
+	select_bad_process(oc, oc->memcg);
 	/* Found nothing?!?! Either we hang forever, or we panic. */
 	if (!oc->chosen && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
 		dump_header(oc, NULL);
-- 
2.7.4