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Date: Fri, 10 Jul 2015 00:25:47 +0200 From: Oleg Nesterov <oleg@...hat.com> To: Ingo Molnar <mingo@...nel.org>, Srikar Dronamraju <srikar@...ux.vnet.ibm.com> Cc: Andy Lutomirski <luto@...capital.net>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, linux-kernel@...r.kernel.org Subject: [PATCH v2 3/3] 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@...hat.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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