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Date: Thu, 26 Apr 2012 14:40:48 -0700 (PDT)
From: David Rientjes <rientjes@...gle.com>
To: Dave Jones <davej@...hat.com>, linux-mm@...ck.org,
Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: 3.4-rc4 oom killer out of control.
On Thu, 26 Apr 2012, Dave Jones wrote:
> On a test machine that was running my system call fuzzer, I just saw
> the oom killer take out everything but the process that was doing all
> the memory exhausting.
>
Would it be possible to try the below patch? It should kill the thread
using the most memory (which happens to only be a couple more megabytes on
your system), but it might just delay the inevitable since the system is
still in a pretty bad state.
KOSAKI-san suggested doing this before and I think it's the best direction
to go in anyway.
---
fs/proc/base.c | 5 +++--
include/linux/oom.h | 5 +++--
mm/oom_kill.c | 39 ++++++++++++++-------------------------
3 files changed, 20 insertions(+), 29 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -410,12 +410,13 @@ static const struct file_operations proc_lstats_operations = {
static int proc_oom_score(struct task_struct *task, char *buffer)
{
+ unsigned long totalpages = totalram_pages + total_swap_pages;
unsigned long points = 0;
read_lock(&tasklist_lock);
if (pid_alive(task))
- points = oom_badness(task, NULL, NULL,
- totalram_pages + total_swap_pages);
+ points = oom_badness(task, NULL, NULL, totalpages) *
+ 1000 / totalpages;
read_unlock(&tasklist_lock);
return sprintf(buffer, "%lu\n", points);
}
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 3d76475..e4c29bc 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -43,8 +43,9 @@ enum oom_constraint {
extern void compare_swap_oom_score_adj(int old_val, int new_val);
extern int test_set_oom_score_adj(int new_val);
-extern unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
- const nodemask_t *nodemask, unsigned long totalpages);
+extern unsigned long oom_badness(struct task_struct *p,
+ struct mem_cgroup *memcg, const nodemask_t *nodemask,
+ unsigned long totalpages);
extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 46bf2ed5..4bbf085 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -180,10 +180,10 @@ static bool oom_unkillable_task(struct task_struct *p,
* predictable as possible. The goal is to return the highest value for the
* task consuming the most memory to avoid subsequent oom failures.
*/
-unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
- const nodemask_t *nodemask, unsigned long totalpages)
+unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
+ const nodemask_t *nodemask, unsigned long totalpages)
{
- long points;
+ unsigned long points;
if (oom_unkillable_task(p, memcg, nodemask))
return 0;
@@ -198,45 +198,33 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
}
/*
- * The memory controller may have a limit of 0 bytes, so avoid a divide
- * by zero, if necessary.
- */
- if (!totalpages)
- totalpages = 1;
-
- /*
* The baseline for the badness score is the proportion of RAM that each
* task's rss, pagetable and swap space use.
*/
- points = get_mm_rss(p->mm) + p->mm->nr_ptes;
- points += get_mm_counter(p->mm, MM_SWAPENTS);
-
- points *= 1000;
- points /= totalpages;
+ points = get_mm_rss(p->mm) + p->mm->nr_ptes +
+ get_mm_counter(p->mm, MM_SWAPENTS);
task_unlock(p);
/*
* Root processes get 3% bonus, just like the __vm_enough_memory()
* implementation used by LSMs.
*/
- if (has_capability_noaudit(p, CAP_SYS_ADMIN))
- points -= 30;
+ if (has_capability_noaudit(p, CAP_SYS_ADMIN) && totalpages)
+ points -= 30 * totalpages / 1000;
/*
* /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may
* either completely disable oom killing or always prefer a certain
* task.
*/
- points += p->signal->oom_score_adj;
+ points += p->signal->oom_score_adj * totalpages / 1000;
/*
* Never return 0 for an eligible task that may be killed since it's
* possible that no single user task uses more than 0.1% of memory and
* no single admin tasks uses more than 3.0%.
*/
- if (points <= 0)
- return 1;
- return (points < 1000) ? points : 1000;
+ return points <= 0 ? 1 : points;
}
/*
@@ -314,7 +302,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
{
struct task_struct *g, *p;
struct task_struct *chosen = NULL;
- *ppoints = 0;
+ unsigned long chosen_points = 0;
do_each_thread(g, p) {
unsigned int points;
@@ -354,7 +342,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
*/
if (p == current) {
chosen = p;
- *ppoints = 1000;
+ chosen_points = ULONG_MAX;
} else if (!force_kill) {
/*
* If this task is not being ptraced on exit,
@@ -367,12 +355,13 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
}
points = oom_badness(p, memcg, nodemask, totalpages);
- if (points > *ppoints) {
+ if (points > chosen_points) {
chosen = p;
- *ppoints = points;
+ chosen_points = points;
}
} while_each_thread(g, p);
+ *ppoints = chosen_points * 1000 / totalpages;
return chosen;
}
--
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