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

Rafael J. Wysocki
2006-12-18T23:09:08Z

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;