Message-ID: <81c865ca-a9d2-413e-b43d-eedd7e4e88a1@roeck-us.net>
Date: Wed, 15 Oct 2025 10:48:21 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 Feng Chen <feng.chen@...ogic.com>, Matthew Wilcox <willy@...radead.org>,
 Jeff Layton <jlayton@...nel.org>,
 Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Tao Ren <rentao.bupt@...il.com>, Lukas Bulwahn <lukas.bulwahn@...hat.com>,
 Alexei Starovoitov <ast@...nel.org>, Vlastimil Babka <vbabka@...e.cz>
Subject: Re: Linux 6.18-rc1

On 10/15/25 10:28, Liam R. Howlett wrote:
> + Cc Vlastimil, as you are indicating the slab merge.
> 
> 
> * Guenter Roeck <linux@...ck-us.net> [251015 06:02]:
>> On Mon, Oct 13, 2025 at 09:46:44PM -0700, Guenter Roeck wrote:
>>> On Mon, Oct 13, 2025 at 10:08:26AM -0700, Guenter Roeck wrote:
>>>> On Sun, Oct 12, 2025 at 02:04:32PM -0700, Linus Torvalds wrote:
>>>>> Two weeks have passed, and 6.18-rc1 has been tagged and pushed out.
>>>>>
>>>>> Things look fairly normal: size-wise this is pretty much right in the
>>>>> middle of the pack, and nothing particular stands out in the shortlog
>>>>> of merges this merge window appended below. About half the diff is
>>>>> drivers, with the res being all over: vfs and filesystems, arch
>>>>> updates (although much of that is actually devicetree stuff, so it's
>>>>> arguably more driver-related), tooling, rust support etc etc.
>>>>>
>>>>> This was one of the good merge windows where I didn't end up having to
>>>>> bisect any particular problem on nay of the machines I was testing.
>>>>> Let's hope that success mostly translates to the bigger picture too.
>>>>>
>>>>
>>>> Test results don't look that good, unfortunately.:
>>>>
>>> ...
>>>> Qemu test results:
>>>> 	total: 609 pass: 581 fail: 28
>>>> Failed tests:
>> ...
>>>> 	sheb:rts7751r2dplus_defconfig:initrd
>>>> 	sheb:rts7751r2dplus_defconfig:ata:ext2
>>>> 	sheb:rts7751r2dplus_defconfig:usb:ext2
>>>> Unit test results:
>>>> 	pass: 655208 fail: 0
>>>>
>>>
>>
>> Update on the sheb (SH4 big endian) failures below.
> 
> What is the qemu line you use and the memory configuration of that qemu,
> or is this real hardware?
> 
qemu. I tried 6.2.0, 10.0.5, and 10.1.1. Sample command line:

qemu-system-sh4eb -M r2d -kernel arch/sh/boot/zImage \
	-append "console=ttySC1,115200 noiotrap" \
	-serial null -serial stdio -monitor null -nographic -no-reboot

initrd or root file system doesn't really matter because qemu exits
almost immediately.

> Are there sh4 configs that pass?
> 

little endian - all
big endian - none

> It's a bit odd it says "fail: 0" here, Is this message about something
> else?

This are unit (KUNIT) test results. All 655208 executed unit tests passed.
Unit tests not executed because the image crashed or because qemu died are not
counted as failed.

...

>>
>> # bad: [ba9dac987319d4f3969691dcf366ef19c9ed8281] Merge tag 'libnvdimm-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
>> # good: [e5f0a698b34ed76002dc5cff3804a61c80233a7a] Linux 6.17
>> git bisect start 'HEAD' 'v6.17'
>> # good: [58809f614e0e3f4e12b489bddf680bfeb31c0a20] Merge tag 'drm-next-2025-10-01' of https://gitlab.freedesktop.org/drm/kernel
>> git bisect good 58809f614e0e3f4e12b489bddf680bfeb31c0a20
>> # bad: [8804d970fab45726b3c7cd7f240b31122aa94219] Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
>> git bisect bad 8804d970fab45726b3c7cd7f240b31122aa94219
>> # good: [30c3055f9c0d84a67b8fd723bdec9b1b52b3c695] xsk: wrap generic metadata handling onto separate function
>> git bisect good 30c3055f9c0d84a67b8fd723bdec9b1b52b3c695
>> # good: [f79e772258df311c2cb21594ca0996318e720d28] Merge tag 'media/v6.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
>> git bisect good f79e772258df311c2cb21594ca0996318e720d28
>> # good: [f1455695d2d99894b65db233877acac9a0e120b9] Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
>> git bisect good f1455695d2d99894b65db233877acac9a0e120b9
>> # good: [a16c46c2402026162111ed9fd1fc28d25223443e] dma-remap: drop nth_page() in dma_common_contiguous_remap()
>> git bisect good a16c46c2402026162111ed9fd1fc28d25223443e
>> # good: [a5883fa94295f1ef2473eadd84cc1e24dab9ae18] selftests/mm: gup_tests: option to GUP all pages in a single call
>> git bisect good a5883fa94295f1ef2473eadd84cc1e24dab9ae18
>> # good: [08498be43ee676d8a5eefb22278266322578a3e0] mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL
>> git bisect good 08498be43ee676d8a5eefb22278266322578a3e0
>> # good: [719a42e563bb087758500e43e67a57b27f303c4c] maple_tree: Convert forking to use the sheaf interface
>> git bisect good 719a42e563bb087758500e43e67a57b27f303c4c
>> # good: [b9120619246d733a27e5e93c29e86f2e0401cfc5] Merge series "SLUB percpu sheaves"
>> git bisect good b9120619246d733a27e5e93c29e86f2e0401cfc5
>> # bad: [24d9e8b3c9c8a6f72c8b4c196a703e144928d919] Merge tag 'slab-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
>> git bisect bad 24d9e8b3c9c8a6f72c8b4c196a703e144928d919
>> # good: [83382af9ddc3cb0ef43f67d049b461720ad785e6] slab: Make slub local_(try)lock more precise for LOCKDEP
>> git bisect good 83382af9ddc3cb0ef43f67d049b461720ad785e6
>> # good: [af92793e52c3a99b828ed4bdd277fd3e11c18d08] slab: Introduce kmalloc_nolock() and kfree_nolock().
>> git bisect good af92793e52c3a99b828ed4bdd277fd3e11c18d08
>> # good: [ca74b8cadaad4b179f77f1f4dc3d288be9a580f1] Merge series "slab: Re-entrant kmalloc_nolock()"
>> git bisect good ca74b8cadaad4b179f77f1f4dc3d288be9a580f1
>> # good: [07fdad3a93756b872da7b53647715c48d0f4a2d0] Merge tag 'net-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
>> git bisect good 07fdad3a93756b872da7b53647715c48d0f4a2d0
>> # first bad commit: [24d9e8b3c9c8a6f72c8b4c196a703e144928d919] Merge tag 'slab-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
>>
>> I had to revert commit 719a42e563bb ("maple_tree: Convert forking to use
>> the sheaf interface") and commit af92793e52c3 ("slab: Introduce
>> kmalloc_nolock() and kfree_nolock()") in the 'slab-for-6.18' branch to fix
>> the problem. The first patch can not be reverted in mainline since other
>> patches depend on it.
> 
> Both 719a42e563bb and af92793e52c3 are listed as good in your bisect
> above.  Why are the two commits you name as the cause listed as 'good'?
> 
> What did you revert to get sh4 to work, and from which git branch?
> 
> What do you mean "can not be reverted in mainline"?  And which is "the
> first patch", I'm assuming the first one you listed (719a42e563bb)?
> 

I checked out a test branch at 24d9e8b3c9c, rebased it on top of
24d9e8b3c9c8a6~1 (07fdad3a93756b8), and ran another bisect. Results:

# bad: [c5e19dc4c1db098456ee6a924e276a26e692f26c] slab: Introduce kmalloc_nolock() and kfree_nolock().
# good: [07fdad3a93756b872da7b53647715c48d0f4a2d0] Merge tag 'net-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
git bisect start 'HEAD' '07fdad3a93756b872da7b53647715c48d0f4a2d0'
# good: [10f17a5a3befa328bd9a78ca6b799dd1933f108b] maple_tree: remove redundant __GFP_NOWARN
git bisect good 10f17a5a3befa328bd9a78ca6b799dd1933f108b
# good: [f97515baad5efa6e1963abd37188fad42515edc8] maple_tree: Replace mt_free_one() with kfree()
git bisect good f97515baad5efa6e1963abd37188fad42515edc8
# bad: [4df642aa2128c2c346f9c945bddbae37c59bba82] locking/local_lock: Introduce local_lock_is_locked().
git bisect bad 4df642aa2128c2c346f9c945bddbae37c59bba82
# good: [a20be9b8014abfe68acc2efd81bfb5d2dd4eaf34] maple_tree: Prefilled sheaf conversion and testing
git bisect good a20be9b8014abfe68acc2efd81bfb5d2dd4eaf34
# bad: [40696586bc008ad34db8135c35ec4b459691af3c] maple_tree: Convert forking to use the sheaf interface
git bisect bad 40696586bc008ad34db8135c35ec4b459691af3c
# good: [8387347ae261c5e74e9db3f73b91d47f11f8d6f8] maple_tree: Add single node allocation support to maple state
git bisect good 8387347ae261c5e74e9db3f73b91d47f11f8d6f8
# first bad commit: [40696586bc008ad34db8135c35ec4b459691af3c] maple_tree: Convert forking to use the sheaf interface

Reverting just 40696586bc008 in that branch didn't help. So I reverted "slab: Introduce
kmalloc_nolock() and kfree_nolock()" in that branch as well, and the image started
passing.
In mainline, 719a42e563bb ("maple_tree: Convert forking to use the sheaf interface")
can be reverted, but trying to revert af92793e52c3 results in:

CONFLICT (content): Merge conflict in mm/slub.c

Guenter

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