Commit-ID: 2a742cedcf13572999436676cbe36c3a9b733b0f Gitweb: http://git.kernel.org/tip/2a742cedcf13572999436676cbe36c3a9b733b0f Author: Oleg Nesterov <oleg@xxxxxxxxxx> AuthorDate: Tue, 21 Jul 2015 15:40:36 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Fri, 31 Jul 2015 10:38:07 +0200 uprobes: Fix the waitqueue_active() check in xol_free_insn_slot() The xol_free_insn_slot()->waitqueue_active() check is buggy. We need mb() after we set the conditon for wait_event(), or xol_take_insn_slot() can miss the wakeup. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Pratyush Anand <panand@xxxxxxxxxx> Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20150721134036.GA4799@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/events/uprobes.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 2d5b7bd..4e5e979 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1337,6 +1337,7 @@ static void xol_free_insn_slot(struct task_struct *tsk) clear_bit(slot_nr, area->bitmap); atomic_dec(&area->slot_count); + smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ if (waitqueue_active(&area->wq)) wake_up(&area->wq); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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