linux-kernel - Re: PowerPC guest getting "BUG: scheduling while atomic" on linux-next-20210623 during secondary CPUs bringup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 25 Jun 2021 11:16:08 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Bharata B Rao <bharata@...ux.ibm.com>
Cc:     linux-next@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        LKML <linux-kernel@...r.kernel.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: PowerPC guest getting "BUG: scheduling while atomic" on
 linux-next-20210623 during secondary CPUs bringup

* Bharata B Rao <bharata@...ux.ibm.com> [2021-06-24 21:25:09]:

> A PowerPC KVM guest gets the following BUG message when booting
> linux-next-20210623:
> 
> smp: Bringing up secondary CPUs ...
> BUG: scheduling while atomic: swapper/1/0/0x00000000
> no locks held by swapper/1/0.
> Modules linked in:
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.13.0-rc7-next-20210623
> Call Trace:
> [c00000000ae5bc20] [c000000000badc64] dump_stack_lvl+0x98/0xe0 (unreliable)
> [c00000000ae5bc60] [c000000000210200] __schedule_bug+0xb0/0xe0
> [c00000000ae5bcd0] [c000000001609e28] __schedule+0x1788/0x1c70
> [c00000000ae5be20] [c00000000160a8cc] schedule_idle+0x3c/0x70
> [c00000000ae5be50] [c00000000022984c] do_idle+0x2bc/0x420
> [c00000000ae5bf00] [c000000000229d88] cpu_startup_entry+0x38/0x40
> [c00000000ae5bf30] [c0000000000666c0] start_secondary+0x290/0x2a0
> [c00000000ae5bf90] [c00000000000be54] start_secondary_prolog+0x10/0x14
> 
> <The above repeats for all the secondary CPUs>
> 
> smp: Brought up 2 nodes, 16 CPUs
> numa: Node 0 CPUs: 0-7
> numa: Node 1 CPUs: 8-15
> 
> This seems to have started from next-20210521 and isn't seen on
> next-20210511.
> 

Bharata,

I think the regression is due to Commit f1a0a376ca0c ("sched/core:
Initialize the idle task with preemption disabled")

Can you please try with the above commit reverted?

-- 
Thanks and Regards
Srikar Dronamraju