diff options
| author | Andrew Morton <akpm@osdl.org> | 2006-04-18 22:20:38 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-04-19 09:13:49 -0700 |
| commit | 97c2c9b84d0c1edf4926b13661d5af3f0edccbce (patch) | |
| tree | bc986808cd7b5a8219a0c40ca9fdfc40524883e4 | |
| parent | 75129e297e861e6c61038aa4cdbf604b022de4ff (diff) | |
[PATCH] oom-kill: mm locking fix
Dave Peterson <dsp@llnl.gov> points out that badness() is playing with
mm_structs without taking a reference on them.
mmput() can sleep, so taking a reference here (inside tasklist_lock) is
hard. Fix it up via task_lock() instead.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | mm/oom_kill.c | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 78747afad6b..9a643c4bf77 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -46,15 +46,25 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) { unsigned long points, cpu_time, run_time, s; - struct list_head *tsk; + struct mm_struct *mm; + struct task_struct *child; - if (!p->mm) + task_lock(p); + mm = p->mm; + if (!mm) { + task_unlock(p); return 0; + } /* * The memory size of the process is the basis for the badness. */ - points = p->mm->total_vm; + points = mm->total_vm; + + /* + * After this unlock we can no longer dereference local variable `mm' + */ + task_unlock(p); /* * Processes which fork a lot of child processes are likely @@ -64,11 +74,11 @@ 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. */ - list_for_each(tsk, &p->children) { - struct task_struct *chld; - chld = list_entry(tsk, struct task_struct, sibling); - if (chld->mm != p->mm && chld->mm) - points += chld->mm->total_vm/2 + 1; + list_for_each_entry(child, &p->children, sibling) { + task_lock(child); + if (child->mm != mm && child->mm) + points += child->mm->total_vm/2 + 1; + task_unlock(child); } /* |