Re: [BUG -next 20181008] list corruption with "mm/slub: remove useless condition in deactivate_slab"

[Pingfan Liu]

On Tue, Oct 9, 2018 at 2:35 PM Heiko Carstens <heiko.carstens@xxxxxxxxxx> wrote:
>
> Hello,
>
> with linux-next for 20181008 I can reliably crash my system with lot's of
> debugging options enabled on s390. List debugging triggers the list
> corruption below, which I could bisect down to this commit:
>
> fde06e07750477f049f12d7d471ffa505338a3e7 is the first bad commit
> commit fde06e07750477f049f12d7d471ffa505338a3e7
> Author: Pingfan Liu <kernelfans@xxxxxxxxx>
> Date:   Thu Oct 4 07:43:01 2018 +1000
>
>     mm/slub: remove useless condition in deactivate_slab
>
>     The var l should be used to reflect the original list, on which the page
>     should be.  But c->page is not on any list.  Furthermore, the current code
>     does not update the value of l.  Hence remove the related logic
>
>     Link: http://lkml.kernel.org/r/1537941430-16217-1-git-send-email-kernelfans@xxxxxxxxx
>     Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
>     Acked-by: Christoph Lameter <cl@xxxxxxxxx>
>     Cc: Pekka Enberg <penberg@xxxxxxxxxx>
>     Cc: David Rientjes <rientjes@xxxxxxxxxx>
>     Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>     Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>     Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
>
> list_add double add: new=000003d1029ecc08, prev=000000008ff846d0,next=000003d1029ecc08.
> ------------[ cut here ]------------
> kernel BUG at lib/list_debug.c:31!
> illegal operation: 0001 ilc:1 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 3 PID: 106 Comm: (sd-executor) Not tainted 4.19.0-rc6-00291-gfde06e077504 #21
> Hardware name: IBM 2964 NC9 702 (z/VM 6.4.0)
> Krnl PSW : (____ptrval____) (____ptrval____) (__list_add_valid+0x98/0xa8)
>            R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 RI:0 EA:3
> Krnl GPRS: 0000000074311fdf 0000000080000001 0000000000000058 0000000000e7b8b2
>            0000000000000000 0000000075438c64 00000000a7b31928 001c007b00000000
>            000000008fe99d00 00000000a7b31b40 000003d1029ecc08 00000000a7c03a80
>            000003d1029ecc08 000000008ff84680 00000000007b5674 00000000a7c03960
> Krnl Code: 00000000007b5668: c0200034734a        larl    %r2,e43cfc
>            00000000007b566e: c0e5ffd0cf51        brasl   %r14,1cf510
>           #00000000007b5674: a7f40001            brc     15,7b5676
>           >00000000007b5678: a7290001            lghi    %r2,1
>            00000000007b567c: ebcff0a00004        lmg     %r12,%r15,160(%r15)
>            00000000007b5682: 07fe                bcr     15,%r14
>            00000000007b5684: 0707                bcr     0,%r7
>            00000000007b5686: 0707                bcr     0,%r7
> Call Trace:
> ([<00000000007b5674>] __list_add_valid+0x94/0xa8)
>  [<000000000037d30e>] deactivate_slab.isra.15+0x45e/0x810
>  [<000000000037ede4>] ___slab_alloc+0x76c/0x7c0
>  [<000000000037eeb0>] __slab_alloc.isra.16+0x78/0xa8
>  [<00000000003808c8>] kmem_cache_alloc+0x160/0x458
>  [<0000000000141a3a>] vm_area_dup+0x3a/0x60
>  [<0000000000142f0a>] copy_process+0xd72/0x2100
>  [<000000000014449a>] _do_fork+0xba/0x688
>  [<0000000000144bb0>] sys_clone+0x48/0x50
>  [<0000000000b8faf0>] system_call+0xd8/0x2d0
> INFO: lockdep is turned off.
> Last Breaking-Event-Address:
>  [<00000000007b5674>] __list_add_valid+0x94/0xa8
>
> Kernel panic - not syncing: Fatal exception: panic_on_oops
>

Sorry that just see this email, and reply late.
I think it is caused by the uinon page->lru and page->next. It can be fixed by:
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 3a1a1db..4aa0fb5 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -56,6 +56,7 @@ struct kmem_cache_cpu {
 #define slub_set_percpu_partial(c, p)          \
 ({                                             \
        slub_percpu_partial(c) = (p)->next;     \
+       p->next = NULL; \
 })

I will do some test and post the fix.

Thanks,
Pingfan