Re: nfs_scan_commit: BUG: unable to handle page fault for address: 000000001d473c07

[Trond Myklebust <trondmy@hammerspace.com>]

On Thu, 2022-09-22 at 13:42 +0200, Paul Menzel wrote:
> Dear Trond,
> 
> 
> Thank you for the quick reply.
> 
> Am 21.09.22 um 14:44 schrieb Trond Myklebust:
> 
> > On Wed, 2022-09-21 at 13:42 +0200, Paul Menzel wrote:
> 
> > > Moving from Linux 5.10.113 to 5.15.69, starting Mozilla
> > > Thunderbird or
> > > Mozilla Firefox with the home on NFS, both programs get killed,
> > > and
> > > Linux 5.15.69 logs:
> > > 
> > > ```
> > > [ 3827.604396] BUG: unable to handle page fault for address:
> > > 000000001d473c07
> > > [ 3827.611297] #PF: supervisor read access in kernel mode
> > > [ 3827.616452] #PF: error_code(0x0000) - not-present page
> > > [ 3827.621604] PGD 0 P4D 0
> > > [ 3827.624152] Oops: 0000 [#1] SMP PTI
> > > [ 3827.627657] CPU: 0 PID: 2378 Comm: firefox Not tainted
> > > 5.15.69.mx64.435 #1
> > > [ 3827.634551] Hardware name: Dell Inc. Precision Tower
> > > 3620/0MWYPT, BIOS 2.20.0 12/09/2021
> 
> […]
> 
> > > [ 3827.743328] Call Trace:
> > > [ 3827.745779]  <TASK>
> > > [ 3827.747883]  nfs_scan_commit+0x76/0xb0 [nfs]
> > > [ 3827.752167]  __nfs_commit_inode+0x108/0x180 [nfs]
> > > [ 3827.756886]  nfs_wb_all+0x59/0x110 [nfs]
> > > [ 3827.760822]  nfs4_inode_return_delegation+0x58/0x90 [nfsv4]
> > > [ 3827.766413]  nfs4_proc_remove+0x101/0x110 [nfsv4]
> > > [ 3827.771130]  nfs_unlink+0xf5/0x2d0 [nfs]
> > > [ 3827.775065]  vfs_unlink+0x10b/0x280
> > > [ 3827.778563]  do_unlinkat+0x19e/0x2c0
> > > [ 3827.782158]  __x64_sys_unlink+0x3e/0x60
> > > [ 3827.786002]  ? __x64_sys_readlink+0x1b/0x30
> > > [ 3827.790192]  do_syscall_64+0x40/0x90
> > > [ 3827.793779]  entry_SYSCALL_64_after_hwframe+0x61/0xcb
> 
> […]
> 
> > > ```
> > > 
> > 
> > Does cherry-picking commit 6e176d47160c ("NFSv4: Fixes for
> > nfs4_inode_return_delegation()") into 5.15.69 from the upstream
> > kernel
> > tree fix the problem?
> > 
> > 8<---------------------------------------------------
> > From 6e176d47160cec8bcaa28d9aa06926d72d54237c Mon Sep 17 00:00:00
> > 2001
> > From: Trond Myklebust <trond.myklebust@hammerspace.com>
> > Date: Sun, 10 Oct 2021 10:58:12 +0200
> > Subject: [PATCH] NFSv4: Fixes for nfs4_inode_return_delegation()
> 
> […]
> 
> Indeed with that commit, present since v5.16-rc1, we are unable to 
> reproduce the issue, so it seems to be the fix. It looks like there
> are 
> not a lot of 5.15 NFS users out there. ;-)
> 

I believe this is a dependency that was introduced by the back port of
commit e591b298d7ec ("NFS: Save some space in the inode") into 5.15.68.
So the reason it wasn't seen is because the change is very recent.

FYI Greg and Sasha: please also consider pulling 6e176d47160c ("NFSv4:
Fixes for nfs4_inode_return_delegation()") into that stable series.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com