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Message-ID: <d024b846-9282-4ecd-eafd-2e5571932a72@suse.cz>
Date: Tue, 10 Jan 2023 15:09:36 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Oliver Sang <oliver.sang@...el.com>
Cc: Hyeonggon Yoo <42.hyeyoo@...il.com>, oe-lkp@...ts.linux.dev,
lkp@...el.com, Mike Rapoport <rppt@...ux.ibm.com>,
Christoph Lameter <cl@...ux.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, Matthew Wilcox <willy@...radead.org>
Subject: Re: [linus:master] [mm, slub] 0af8489b02:
kernel_BUG_at_include/linux/mm.h
On 1/10/23 14:53, Oliver Sang wrote:
> hi all,
>
> On Mon, Jan 09, 2023 at 10:01:15PM +0800, Oliver Sang wrote:
>>
>> On Fri, Jan 06, 2023 at 11:13:15AM +0100, Vlastimil Babka wrote:
>>
>> > And if the rate at the parent (has it increased thanks to the
>> > DEBUG_PAGEALLOC?) is sufficient to bisect to the truly first bad commit. Thanks!
>>
>> got it. Thanks for suggestion!
>>
>> since 0af8489b02 is based on v6.1-rc2, we will test (both rectorture and boot)
>> with same config upon v6.1-rc2 to see if it's really clean there.
>> if so we will use dmesg.invalid_opcode:#[##] to trigger new bisect.
>>
>> will keep you updated. Thanks
>
> by more tests, we cannot make sure the v6.1-rc2 is clean, so we also checked
> v6.1-rc1 and v6.0. from results, we have low confidence that we can make a
> successful bisection based on them [1][2]. could you suggest?
So am I reading it right, that the probleam appears to be introduced between
v6.0 (0 failures) and v6.1-rc1 (>0 failures)? But agree that with such low
incidence, it's hard to bisect.
> a further information not sure if it's helpful, [1][2] are both i386 based.
> we also tried to run boot tests on x86_64 upon commit 0af8489b02, whatever
> with or without CONFIG_DEBUG_PAGEALLOC/CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT,
> we never obseve similar issues (also run 999 times).
Yeah it looks very much like something that manifests only on i386 (perhaps
only in QEMU as well?) and never x86_64.
What might be interesting then is v6.1-rc1 with further modified config to
enabled CONFIG_SLUB_DEBUG and CONFIG_SLUB_DEBUG_ON. Maybe it will catch the
culprit sooner. Or maybe it will obscure the bug instead, unfortunately.
Thanks for all your effort!
> [1]
> boot results:
> =========================================================================================
> compiler/kconfig/rootfs/sleep/tbox_group/testcase:
> gcc-11/i386-randconfig-a012-20221226+CONFIG_DEBUG_PAGEALLOC+CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT/debian-11.1-i386-20220923.cgz/1/vm-snb/boot
>
> v6.0 v6.1-rc1 v6.1-rc2 56d5a2b9ba85a390473e86b4fe4 0af8489b0216fa1dd83e264bef8
> ---------------- --------------------------- --------------------------- --------------------------- ---------------------------
> fail:runs %reproduction fail:runs %reproduction fail:runs %reproduction fail:runs %reproduction fail:runs
> | | | | | | | | |
> :999 0% 2:999 0% 1:999 1% 11:999 21% 208:999 dmesg.invalid_opcode:#[##]
> :999 0% :999 0% :999 0% 2:999 5% 51:999 dmesg.kernel_BUG_at_include/linux/mm.h
> :999 0% 1:999 0% :999 0% 4:999 4% 40:999 dmesg.kernel_BUG_at_include/linux/page-flags.h
> :999 0% 1:999 0% 1:999 0% 4:999 11% 111:999 dmesg.kernel_BUG_at_lib/list_debug.c
> :999 0% :999 0% :999 0% :999 0% 2:999 dmesg.kernel_BUG_at_mm/page_alloc.c
> :999 0% :999 0% :999 0% 1:999 0% 3:999 dmesg.kernel_BUG_at_mm/usercopy.c
>
> [2]
> rcutorture results:
> =========================================================================================
> compiler/kconfig/rootfs/runtime/tbox_group/test/testcase/torture_type:
> gcc-11/i386-randconfig-a012-20221226+CONFIG_DEBUG_PAGEALLOC+CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT/debian-11.1-i386-20220923.cgz/300s/vm-snb/default/rcutorture/tasks-tracing
>
> v6.0 v6.1-rc1 v6.1-rc2 56d5a2b9ba85a390473e86b4fe4 0af8489b0216fa1dd83e264bef8
> ---------------- --------------------------- --------------------------- --------------------------- ---------------------------
> fail:runs %reproduction fail:runs %reproduction fail:runs %reproduction fail:runs %reproduction fail:runs
> | | | | | | | | |
> :999 0% 3:999 0% :999 1% 8:998 20% 200:999 dmesg.invalid_opcode:#[##]
> :999 0% :999 0% :999 0% :998 5% 51:999 dmesg.kernel_BUG_at_include/linux/mm.h
> :999 0% :999 0% :999 0% 3:998 4% 42:999 dmesg.kernel_BUG_at_include/linux/page-flags.h
> :999 0% 3:999 0% :999 0% 4:998 10% 102:999 dmesg.kernel_BUG_at_lib/list_debug.c
> :999 0% :999 0% :999 0% :998 0% 2:999 dmesg.kernel_BUG_at_mm/page_alloc.c
> :999 0% :999 0% :999 0% 1:998 0% 3:999 dmesg.kernel_BUG_at_mm/usercopy.c
>
>>
>> >
>> >
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