| Date | Tue, 21 Jul 2015 15:40:36 +0200 | From | Oleg Nesterov <> | Subject | [PATCH v3 14/14] uprobes: fix the waitqueue_active() check in xol_free_insn_slot() |
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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@redhat.com> --- kernel/events/uprobes.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
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); -- 1.5.5.1
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