On Fri, May 10, 2013 at 11:52 PM, Toralf Förster <toralf.foerster@xxxxxx> wrote:
> The bisected commit introduced this WARNING: on a user mode linux guest
> if the UML guest is fuzz tested with trinity :
>
>
> 2013-05-10T22:38:42.191+02:00 trinity kernel: ------------[ cut here ]------------
> 2013-05-10T22:38:42.191+02:00 trinity kernel: WARNING: at mm/slab_common.c:376 kmalloc_slab+0x33/0x80()
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fda8: [<08336928>] dump_stack+0x22/0x24
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fdc0: [<0807c2da>] warn_slowpath_common+0x5a/0x80
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fde8: [<0807c3a3>] warn_slowpath_null+0x23/0x30
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fdf8: [<080dfc93>] kmalloc_slab+0x33/0x80
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fe0c: [<080f8beb>] __kmalloc_track_caller+0x1b/0x110
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fe30: [<080dc866>] memdup_user+0x26/0x70
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fe4c: [<080dca6e>] strndup_user+0x3e/0x60
> 2013-05-10T22:38:42.191+02:00 trinity kernel: 40e2fe68: [<0811ba60>] copy_mount_string+0x30/0x50
> 2013-05-10T22:38:42.195+02:00 trinity kernel: 40e2fe7c: [<0811c46a>] sys_mount+0x1a/0xe0
> 2013-05-10T22:38:42.195+02:00 trinity kernel: 40e2feac: [<08062b32>] handle_syscall+0x82/0xb0
> 2013-05-10T22:38:42.195+02:00 trinity kernel: 40e2fef4: [<0807520d>] userspace+0x46d/0x590
> 2013-05-10T22:38:42.195+02:00 trinity kernel: 40e2ffec: [<0805f7fc>] fork_handler+0x6c/0x70
> 2013-05-10T22:38:42.195+02:00 trinity kernel: 40e2fffc: [<00000000>] 0x0
> 2013-05-10T22:38:42.195+02:00 trinity kernel:
> 2013-05-10T22:38:42.195+02:00 trinity kernel: ---[ end trace 17e5931469d0697d ]---
>
>
> Tested with host kernel 3.9.1, host and client were 32bit stable Gentoo Linux.
>
>
> 6286ae97d10ea2b5cd90532163797ab217bfdbdf is the first bad commit
> commit 6286ae97d10ea2b5cd90532163797ab217bfdbdf
> Author: Christoph Lameter <cl@xxxxxxxxx>
> Date: Fri May 3 15:43:18 2013 +0000
>
> slab: Return NULL for oversized allocations
>
> The inline path seems to have changed the SLAB behavior for very large
> kmalloc allocations with commit e3366016 ("slab: Use common
> kmalloc_index/kmalloc_size functions"). This patch restores the old
> behavior but also adds diagnostics so that we can figure where in the
> code these large allocations occur.
>
> Reported-and-tested-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/201305040348.CIF81716.OStQOHFJMFLOVF@xxxxxxxxxxxxxxxxxxx
> [ penberg@xxxxxxxxxx: use WARN_ON_ONCE ]
> Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxx>
>
So, we trigger "if (WARN_ON_ONCE(size > KMALLOC_MAX_SIZE))".
Now I'm wondering what kind of argument string trinity gave to mount().
How long is it?
BTW: Toralf, why are you sending this to user-mode-linux-*user*@lists...?
We also have a -devel list. Please at least CC me.
Otherwise it is most likely that I miss such reports...
--
Thanks,
//richard
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