On Thu, Aug 22, 2019 at 02:39:26PM -0500, Jason L Tibbitts III wrote: > I now have another user reporting the same failure of readdir on a long > directory which showed up in 5.1.20 and was traced to > 3536b79ba75ba44b9ac1a9f1634f2e833bbb735c. I'm not sure what to do to > get more traction besides reposting and adding some addresses to the CC > list. If there is any information I can provide which might help to get > to the bottom of this, please let me know. > > To recap: > > 5.1.20 introduced a regression reading some large directories. In this > case, the directory should have 7800 files or so in it: > > [root@ld00 ~]# ls -l ~dblecher|wc -l > ls: reading directory '/home/dblecher': Input/output error > 1844 > [root@ld00 ~]# cat /proc/version Linux version 5.1.20-300.fc30.x86_64 (mockbuild@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) (gcc version 9.1.1 20190503 (Red Hat 9.1.1-1) (GCC)) #1 SMP Fri Jul 26 15:03:11 UTC 2019 > > (The server is a Centos 7 machine running kernel 3.10.0-957.12.2.el7.x86_64.) > > Building a kernel which reverts commit 3536b79ba75ba44b9ac1a9f1634f2e833bbb735c: > Revert "NFS: readdirplus optimization by cache mechanism" (memleak) Looks like that's db531db951f950b8 upstream. (Do you know if it's reproduceable upstream as well?) > fixes the issue, but of course that revert was fixing a real issue so > I'm not sure what to do. > > I can trivially reproduce this by simply trying to list the problematic > directories but I'm not sure how to construct such a directory; simply > creating 10000 files doesn't cause the problem for me. Maybe it depends on having names of the right length to place some bit of xdr on a boundary. I wonder if it'd be possible to reproduce just by varying the name lengths randomly till you hit it. The fact that the problematic patch fixed a memory leak also makes me wonder if it might have gone to far and freed something out from under the readdir code. > I am willing to > test patches and can build my own kernels, and I'm happy to provide any > debugging information you might require. Unfortunately I don't know > enough to dig in and figure out for myself what's going wrong. > > I did file https://bugzilla.redhat.com/show_bug.cgi?id=1740954 just to > have this in a bug tracker somewhere. I'm happy to file one somewhere > else if that would help. No clever debugging ideas off the top of my head, I'm afraid. I might start by patching the kernel or doing some tracing to figure out exactly where that EIO is being generated? --b.
