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SubjectRe: [PATCH 3/5] oom: Fix child process iteration properly
Date
> On 06/01, KOSAKI Motohiro wrote:
> >
> > @@ -88,6 +88,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
> > {
> > unsigned long points, cpu_time, run_time;
> > struct task_struct *c;
> > + struct task_struct *t = p;
>
> This initialization should be moved down to
>
> > + do {
> > + list_for_each_entry(c, &t->children, sibling) {
> > + child = find_lock_task_mm(c);
> > + if (child) {
> > + if (child->mm != p->mm)
> > + points += child->mm->total_vm/2 + 1;
> > + task_unlock(child);
> > + }
> > }
> > - }
> > + } while_each_thread(p, t);
>
> this loop. We have "p = find_lock_task_mm(p)" in between which can change p.
>
> Apart from this, I think the whole series is nice.

Nich catch!

simple incremental patch is here.

========================================================
Subject: [PATCH] Fix oom: Fix child process iteration properly
p can be changed by find_lock_task_mm()

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
mm/oom_kill.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 9631f1b..9e7f0f9 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -88,7 +88,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
{
unsigned long points, cpu_time, run_time;
struct task_struct *c;
- struct task_struct *t = p;
+ struct task_struct *t;
struct task_struct *child;
int oom_adj = p->signal->oom_adj;
struct task_cputime task_time;
@@ -126,6 +126,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
* child is eating the vast majority of memory, adding only half
* to the parents will make the child our kill candidate of choice.
*/
+ t = p;
do {
list_for_each_entry(c, &t->children, sibling) {
child = find_lock_task_mm(c);
--
1.6.5.2






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