Hi Chaitanya, On Thu, Nov 09, 2023 at 05:00:09PM +0000, Borah, Chaitanya Kumar wrote: > Hello Krister, > > Hope you are doing well. I am Chaitanya from the linux graphics team in Intel. > > This mail is regarding a regression we are seeing in our CI runs[1] for some machines (dg2 and adl-p) on linux-next repository. > > Since the version next-20231107 [2], we are seeing the following error > ``````````````````````````````````````````````````````````````````````````````` > <4>[ 32.015910] stack segment: 0000 [#1] PREEMPT SMP NOPTI > <4>[ 32.021048] CPU: 15 PID: 766 Comm: fusermount Not tainted 6.6.0-next-20231107-next-20231107-g5cd631a52568+ #1 > <4>[ 32.031135] Hardware name: Intel Corporation Raptor Lake Client Platform/RPL-S ADP-S DDR5 UDIMM CRB, BIOS RPLSFWI1.R00.4221.A00.2305271351 05/27/2023 > <4>[ 32.044657] RIP: 0010:fuse_evict_inode+0x61/0x150 [fuse] > ````````````````````````````````````````````````````````````````````````````````` > > Details log can be found in [3]. > > After bisecting the tree, the following patch [4] seems to be the first "bad" commit > > ````````````````````````````````````````````````````````````````````````````````````````````````````````` > 513dfacefd712bcbfab64e1a9c9c3e0d51c2dca5 is the first bad commit > commit 513dfacefd712bcbfab64e1a9c9c3e0d51c2dca5 > Author: Krister Johansen kjlx@xxxxxxxxxxxxxxxxxx > Date: Fri Nov 3 10:39:47 2023 -0700 > > fuse: share lookup state between submount and its parent > > Fuse submounts do not perform a lookup for the nodeid that they inherit > from their parent. Instead, the code decrements the nlookup on the > submount's fuse_inode when it is instantiated, and no forget is > performed when a submount root is evicted. > > Trouble arises when the submount's parent is evicted despite the > submount itself being in use. In this author's case, the submount was > in a container and deatched from the initial mount namespace via a > MNT_DEATCH operation. When memory pressure triggered the shrinker, the > inode from the parent was evicted, which triggered enough forgets to > render the submount's nodeid invalid. > > Since submounts should still function, even if their parent goes away, > solve this problem by sharing refcounted state between the parent and > its submount. When all of the references on this shared state reach > zero, it's safe to forget the final lookup of the fuse nodeid. > > ````````````````````````````````````````````````````````````````````````````````````````````````````````` > > We also verified that if we revert the patch the issue is not seen. > > Could you please check why the patch causes this regression and provide a fix if necessary? Apologies for the inconvenience. I've reproduced the problem, tested a fix, and am in the process of preparing patches to send to Miklos. I'll cc the people on this e-mail in that thread. > [3] http://gfx-ci.igk.intel.com/tree/linux-next/next-20231109/bat-dg2-14/boot0.txt This link didn't resolve in DNS when I tried to access it. I needed to use intel-gfx-ci.01.org as the hostname instead. Thanks, -K
