From 1eda5166c7640092f512138be6899d050c3d62ed Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 7 Mar 2012 17:54:00 +0400 Subject: [PATCH] staging: android/lowmemorykiller: Don't unregister notifier from atomic context 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 Signed-off-by: Christian Bejram Signed-off-by: Paul E. McKenney Reported-by: John Stultz Signed-off-by: Anton Vorontsov Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/lowmemorykiller.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c index cf4c6f7e6b52..03d1de241408 100644 --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -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); -- 2.20.1