Hello, When waiting for response to fanotify permission events, we currently use uninterruptible waits. That makes code simple however it can cause lots of processes to end up in uninterruptible sleep with hard reboot being the only alternative in case fanotify listener process stops responding (e.g. due to a bug in its implementation) - reported e.g. in [1]. Uninterruptible sleep also makes system hibernation fail if the listener gets frozen before the process generating fanotify permission event (as reported e.g. here [2]). This patch set modifies fanotify so that it will use interruptible wait when waiting for fanotify permission event response. Patches are based on current Linus' tree for the ease of testing (I plan to rebase them on top of Amir's pending changes later). I have also create LTP test which stresses handling of permission events while sending processes signals to test the new code [3] Review, comments, and testing are welcome. [1] https://lore.kernel.org/lkml/153474898224.6806.12518115530793064797.stgit@buzz/ [2] https://lore.kernel.org/lkml/c1bb16b7-9eee-9cea-2c96-a512d8b3b9c7@xxxxxxxx/ [3] https://lwn.net/ml/linux-fsdevel/20190108165307.GA11259@xxxxxxxxxxxxxx/ Changes since v1: * leave pr_debug() calls alone (Amir) * simplify permission event state tracking (Amir) * split some changes into separate patches (Amir) Honza
