Re: linux-5.13.2: warning from kernel/rcu/tree_plugin.h:359

From: Matthew Wilcox
Date: Sun Jul 18 2021 - 17:22:44 EST


On Sun, Jul 18, 2021 at 11:03:51PM +0200, Oleksandr Natalenko wrote:
> + stable@xxxxxxxxxxxxxxx
>
> On neděle 18. července 2021 23:01:24 CEST Oleksandr Natalenko wrote:
> > Hello.
> >
> > On sobota 17. července 2021 22:22:08 CEST Chris Clayton wrote:
> > > I checked the output from dmesg yesterday and found the following warning:
> > >
> > > [Fri Jul 16 09:15:29 2021] ------------[ cut here ]------------
> > > [Fri Jul 16 09:15:29 2021] WARNING: CPU: 11 PID: 2701 at
> > > kernel/rcu/tree_plugin.h:359 rcu_note_context_switch+0x37/0x3d0 [Fri Jul

Could you run ./scripts/faddr2line vmlinux rcu_note_context_switch+0x37/0x3d0

> > > [Fri Jul 16 09:15:29 2021] Call Trace:
> > > [Fri Jul 16 09:15:29 2021] __schedule+0x86/0x810
> > > [Fri Jul 16 09:15:29 2021] schedule+0x40/0xe0
> > > [Fri Jul 16 09:15:29 2021] io_schedule+0x3d/0x60
> > > [Fri Jul 16 09:15:29 2021] wait_on_page_bit_common+0x129/0x390
> > > [Fri Jul 16 09:15:29 2021] ? __filemap_set_wb_err+0x10/0x10
> > > [Fri Jul 16 09:15:29 2021] __lock_page_or_retry+0x13f/0x1d0
> > > [Fri Jul 16 09:15:29 2021] do_swap_page+0x335/0x5b0
> > > [Fri Jul 16 09:15:29 2021] __handle_mm_fault+0x444/0xb20
> > > [Fri Jul 16 09:15:29 2021] handle_mm_fault+0x5c/0x170

You were handling a page fault at the time. The page you wanted was
on swap and this warning fired as a result of waiting for the page
to come back in from swap. There are a number of warnings in that
function, so it'd be good to track down exactly which one it is.