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| author | Oleg Nesterov <oleg@redhat.com> | 2015-07-21 15:40:36 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-07-31 10:38:07 +0200 |
| commit | 2a742cedcf13572999436676cbe36c3a9b733b0f (patch) | |
| tree | bb614fd0d0204a48f9ff739bced7cb45567f9fdb | |
| parent | uprobes: Use vm_special_mapping to name the XOL vma (diff) | |
| download | linux-2a742cedcf13572999436676cbe36c3a9b733b0f.tar.xz linux-2a742cedcf13572999436676cbe36c3a9b733b0f.zip | |
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@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134036.GA4799@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | 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 2d5b7bd337a7..4e5e9798aa0c 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); |