]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commitdiff
staging: android/lowmemorykiller: Don't unregister notifier from atomic context
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Wed, 7 Mar 2012 13:54:00 +0000 (17:54 +0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 7 Mar 2012 21:18:51 +0000 (13:18 -0800)
The lowmemorykiller registers an atomic notifier for notfication of when
the task is freed.  From this atomic notifier callback, it removes the
atomic notifier via task_free_unregister().  This is incorrect because
atomic_notifier_chain_unregister() calls syncronize_rcu(), which can
sleep, which shouldn't be done from an atomic notifier.

Fix this by registering the notifier during init, and only unregister it
if the lowmemorykiller is unloaded.

Rebased to -next by Paul E. McKenney.
Rebased to -next again by Anton Vorontsov.

Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Christian Bejram <christian.bejram@stericsson.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/staging/android/lowmemorykiller.c

index cf4c6f7e6b5201c9ba757ccaf9a9c354fc4b7937..03d1de24140894ec8d147edb965d809d5b7f158c 100644 (file)
@@ -75,10 +75,10 @@ static int
 task_notify_func(struct notifier_block *self, unsigned long val, void *data)
 {
        struct task_struct *task = data;
-       if (task == lowmem_deathpending) {
+
+       if (task == lowmem_deathpending)
                lowmem_deathpending = NULL;
-               task_handoff_unregister(&task_nb);
-       }
+
        return NOTIFY_OK;
 }
 
@@ -175,14 +175,12 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
                             selected->pid, selected->comm,
                             selected_oom_score_adj, selected_tasksize);
                /*
-                * If CONFIG_PROFILING is off, then task_handoff_register()
-                * is a nop. In that case we don't want to stall the killer
-                * by setting lowmem_deathpending.
+                * If CONFIG_PROFILING is off, then we don't want to stall
+                * the killer by setting lowmem_deathpending.
                 */
 #ifdef CONFIG_PROFILING
                lowmem_deathpending = selected;
                lowmem_deathpending_timeout = jiffies + HZ;
-               task_handoff_register(&task_nb);
 #endif
                send_sig(SIGKILL, selected, 0);
                rem -= selected_tasksize;
@@ -200,6 +198,7 @@ static struct shrinker lowmem_shrinker = {
 
 static int __init lowmem_init(void)
 {
+       task_handoff_register(&task_nb);
        register_shrinker(&lowmem_shrinker);
        return 0;
 }
@@ -207,6 +206,7 @@ static int __init lowmem_init(void)
 static void __exit lowmem_exit(void)
 {
        unregister_shrinker(&lowmem_shrinker);
+       task_handoff_unregister(&task_nb);
 }
 
 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);