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

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Message-ID: <7bdd83d7c2442d8096612ad3f821af556dd96015.camel@hammerspace.com>
Date:   Tue, 9 Apr 2019 16:55:47 +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

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?

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