On Fri, Sep 01, 2017 at 04:14:27PM -0600, Liu Bo wrote: > wake_up() will go to check whether someone is on the waiting list with > holding spin_lock(). > > Around some btrfs code, we don't check waitqueue_active() firstly, so > the spin_lock() pair in wake_up() is called even if no one is waiting > on the queue. > > There are more wake_up()s without waitqueue_active(), but these two > are the hottest one I've run into so far. > > Signed-off-by: Liu Bo <bo.li....@oracle.com>
Can you please split the patch and address both separately, as they are not affecting the same data structure? It would be good to mention the other parts of code specifically (not just "around some code"), or briefly describe the state transitions where it matters for the wake ups. A missed wakeup appears as if the system is hung, but it's not a deadlock and we don't have much help debugging that when it happens. I'd like to review that in a way where I can make sure you have checked all the possible lost wakeups. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
