2.6.30-stable review patch. If anyone has any objections, please let us know. ------------------ From: Oleg Nesterov The bug should be "accidently" fixed by recent changes in 2.6.31, all kernels <= 2.6.30 need the fix. The problem was never noticed before, it was found because it causes mysterious failures with GFS mount/umount. Credits to Robert Peterson. He blaimed kthread.c from the very beginning. But, despite my promise, I forgot to inspect the old implementation until he did a lot of testing and reminded me. This led to huge delay in fixing this bug. kthread_stop() does put_task_struct(k) before it clears kthread_stop_info.k. This means another kthread_create() can re-use this task_struct, but the new kthread can still see kthread_should_stop() == T and exit even without calling threadfn(). Reported-by: Robert Peterson Tested-by: Robert Peterson Signed-off-by: Oleg Nesterov Acked-by: Rusty Russell Signed-off-by: Greg Kroah-Hartman --- kernel/kthread.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -216,12 +216,12 @@ int kthread_stop(struct task_struct *k) /* Now set kthread_should_stop() to true, and wake it up. */ kthread_stop_info.k = k; wake_up_process(k); - put_task_struct(k); /* Once it dies, reset stop ptr, gather result and we're done. */ wait_for_completion(&kthread_stop_info.done); kthread_stop_info.k = NULL; ret = kthread_stop_info.err; + put_task_struct(k); mutex_unlock(&kthread_stop_lock); trace_sched_kthread_stop_ret(ret); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/