linux-kernel - Re: 5.1.0-rc4: Oops in __rpc_execute() when trying to boot from NFS

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Date:   Thu, 11 Apr 2019 19:50:15 +0000
From:   Trond Myklebust <trondmy@...merspace.com>
To:     "bfields@...ldses.org" <bfields@...ldses.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "daniel@...que.org" <daniel@...que.org>,
        "jlayton@...nel.org" <jlayton@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: 5.1.0-rc4: Oops in __rpc_execute() when trying to boot from NFS

Hi Daniel,

On Tue, 2019-04-09 at 19:54 +0200, Daniel Mack wrote:
> On 9/4/2019 6:55 PM, Trond Myklebust wrote:
> > On Tue, 2019-04-09 at 18:25 +0200, Daniel Mack wrote:
> > > On 8/4/2019 8:51 PM, Trond Myklebust wrote:
> > > > On Mon, 2019-04-08 at 19:01 +0200, Daniel Mack wrote:
> > > > > Hi,
> > > > > 
> > > > > I'm seeing the Oops below when trying to boot 5.1.0-rc4 on an
> > > > > ARM
> > > > > PXA3xx
> > > > > platform. v5.0 did not show this effect with the same
> > > > > cmdline.
> > > > > 
> > > > Please do bisect if that is at all practical. I'm having
> > > > trouble
> > > > interpreting this Oops.
> > > 
> > > Here you go:
> > > 
> > > 009a82f6437490c262584d65a14094a818bcb747 is the first bad commit
> > > commit 009a82f6437490c262584d65a14094a818bcb747
> > > Author: Trond Myklebust <trond.myklebust@...merspace.com>
> > > Date:   Sat Mar 9 12:07:17 2019 -0500
> > > 
> > >     SUNRPC: Micro-optimise when the task is known not to be
> > > sleeping
> > > 
> > >     In cases where we know the task is not sleeping, try to
> > > optimise
> > >     away the indirect call to task->tk_action() by replacing it
> > > with
> > >     a direct call.
> > >     Only change tail calls, to allow gcc to perform tail call
> > >     elimination.
> > 
> > Ah... It looks like we explicitly turn off tail call optimisation
> > in
> > some ARM configs, so this might be a stack overflow.
> > 
> > Does your config file have THUMB2_AVOID_R_ARM_THM_JUMP11 set?
> 
> Nope. I don't even have THUMB2_KERNEL.
> 
> In the meantime, I tried to trace that with some printks, but the bug
> appears evasive, and the backtrace changes as soon as I modify the
> timing. Hmm.
> 
> Happy to test patches if you have any idea.
> 

Could you please try pulling the 'testing' branch from 
http://git.linux-nfs.org/?p=trondmy/linux-nfs.git;a=shortlog;h=refs/heads/testing

i.e. 'git pull git://git.linux-nfs.org/projects/trondmy/linux-nfs.git
testing'

to see if that suffices to fix the issue you're reporting?

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