On Tue 28-03-17 15:23:58, Ilya Dryomov wrote: > On Tue, Mar 28, 2017 at 2:43 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > On Tue 28-03-17 14:30:45, Greg KH wrote: > >> 4.4-stable review patch. If anyone has any objections, please let me know. > > > > I haven't seen the original patch but the changelog makes me worried. > > How exactly this is a problem? Where do we lockup? Does rbd/libceph take > > any xfs locks? > > No, it doesn't. This is just another instance of "using GFP_KERNEL on > the writeback path may lead to a deadlock" with nothing extra to it. > > XFS is writing out data, libceph messenger worker tries to open > a socket and recurses back into XFS because the sockfs inode is > allocated with GFP_KERNEL. The message with some of the data never > goes out and eventually we get a deadlock. > > I've only included the offending stack trace. I guess I should have > stressed that ceph-msgr workqueue is used for reclaim. Could you be more specific about the lockup scenario. I still do not get how this would lead to a deadlock. -- Michal Hocko SUSE Labs