[PATCH] fix OOM killing of swapoff

These days, if you swapoff when there isn't enough memory, OOM killer gives
"BUG: scheduling while atomic" and the machine hangs: badness() needs to do
its PF_SWAPOFF return after the task_unlock (tasklist_lock is also held
here, so p isn't going to be freed: PF_SWAPOFF might get turned off at any
moment, but that doesn't really matter).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6969cfb..b278b8d 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -60,12 +60,6 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
                return 0;
        }
 
-       /*
-        * swapoff can easily use up all memory, so kill those first.
-        */
-       if (p->flags & PF_SWAPOFF)
-               return ULONG_MAX;
-
        /*
         * The memory size of the process is the basis for the badness.
         */
@@ -76,6 +70,12 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
         */
        task_unlock(p);
 
+       /*
+        * swapoff can easily use up all memory, so kill those first.
+        */
+       if (p->flags & PF_SWAPOFF)
+               return ULONG_MAX;
+
        /*
         * Processes which fork a lot of child processes are likely
         * a good choice. We add half the vmsize of the children if they