| From | Ilya Dryomov <> | Date | Tue, 28 Mar 2017 15:23:58 +0200 | Subject | Re: [PATCH 4.4 48/76] libceph: force GFP_NOIO for socket allocations |
| |
On Tue, Mar 28, 2017 at 2:43 PM, Michal Hocko <mhocko@kernel.org> 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.
Thanks,
Ilya
|