Re: [linux-pm] OOPS: divide error while s2dsk (2.6.20-rc1-mm1)

Nigel Cunningham
2006-12-18T23:16:34Z

Hi.

On Tue, 2006-12-19 at 00:09 +0100, Rafael J. Wysocki wrote:
> Hi,
>
> On Monday, 18 December 2006 23:44, Nigel Cunningham wrote:
> > Hi.
> >
> > On Mon, 2006-12-18 at 23:38 +0100, Rafael J. Wysocki wrote:
> > > On Monday, 18 December 2006 18:02, Jiri Slaby wrote:
> > > > Rafael J. Wysocki wrote:
> > > > > Hi,
> > > > >
> > > > > On Monday, 18 December 2006 12:20, Jiri Slaby wrote:
> > > > >> Hi.
> > > > >>
> > > > >> I got this oops while suspending:
> > > > >> [ 309.366557] Disabling non-boot CPUs ...
> > > > >> [ 309.386563] CPU 1 is now offline
> > > > >> [ 309.387625] CPU1 is down
> > > > >> [ 309.387704] Stopping tasks ... done.
> > > > >> [ 310.030991] Shrinking memory... -<0>divide error: 0000 [#1]
> > > > >> [ 310.456669] SMP
> > > > >> [ 310.456814] last sysfs file:
> > > > >> /devices/pci0000:00/0000:00:1e.0/0000:02:08.0/eth0/statistics/collisions
> > > > >> [ 310.456919] Modules linked in: eth1394 floppy ohci1394 ide_cd ieee1394 cdrom
> > > > >> [ 310.457259] CPU: 0
> > > > >> [ 310.457260] EIP: 0060:[<c0150c9a>] Not tainted VLI
> > > > >> [ 310.457261] EFLAGS: 00210246 (2.6.20-rc1-mm1 #207)
> > > > >> [ 310.457478] EIP is at shrink_slab+0x9e/0x169
> > > > >
> > > > > Looks like we have a problem with slab shrinking here.
> > > > >
> > > > > Could you please use gdb to check what exactly is at shrink_slab+0x9e?
> > > >
> > > > Sure, but not till Friday, sorry (I am away).
> > >
> > > I reproduced this on one box, but then it turned out that EIP was at line 195
> > > of mm/vmscan.c where there was
> > >
> > > do_div(delta, lru_pages + 1);
> > >
> > > Well, I have no idea how this can lead to a divide error (lru_pages is
> > > unsigned).
> > >
> > > I'm unable to reproduce this on another i386 box, so it seems to be somewhat
> > > configuration specific.
> > >
> > > Does 2.6.20-rc1 work for you?
> >
> > I have a patch in -mm that reduces lru_pages by what shrink_all_zones
> > returns. Could shrink_all_zones perhaps be returning incorrect values
> > such that lru_pages ends up becoming -1?
>
> I don't think so, but look at the appended patch. ;-)
>
> Greetings,
> Rafael
>
>
> ---
> Fix a (really bad) typo in shrink_all_memory().
>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
> mm/vmscan.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: linux-2.6.20-rc1-mm1/mm/vmscan.c
> ===================================================================
> --- linux-2.6.20-rc1-mm1.orig/mm/vmscan.c
> +++ linux-2.6.20-rc1-mm1/mm/vmscan.c
> @@ -1569,7 +1569,7 @@ unsigned long shrink_all_memory(unsigned
> sc.swap_cluster_max = nr_pages - ret;
> freed = shrink_all_zones(nr_to_scan, prio, pass, &sc);
> ret += freed;
> - lru_pages =- freed;
> + lru_pages -= freed;
> nr_to_scan = nr_pages - ret;
> if (ret >= nr_pages)
> goto out;

Heh, yeah.

Definitely acked! :)

Nigel