Re: [PATCH 6.1 000/481] 6.1.167-rc1 review

[Mark Brown]

On Tue, Mar 24, 2026 at 02:40:31PM +0100, Jan Kara wrote:
> On Tue 24-03-26 08:34:47, Francesco Dolcini wrote:

> > I have an ext4 Oops on arm

> > [   27.908560] 8<--- cut here ---
> > [   27.911697] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> > [   27.919880] [00000000] *pgd=00000000
> > [   27.923482] Internal error: Oops: 5 [#1] SMP ARM
> > [   27.928117] Modules linked in: 8021q cfg80211 imx_sdma coda_vpu v4l2_jpeg imx_vdoa dw_hdmi_ahb_audio fuse
> > [   27.937784] CPU: 1 PID: 736 Comm: tar Not tainted 6.1.167-rc1-6.8.6-devel+git.67c872a868ac #1
> > [   27.946342] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> > [   27.952889] PC is at ext4_mb_load_buddy_gfp+0xac/0x438

> Can you run this through "addr2line -i" to get exact position in that big
> function? Because from a quick look it doesn't ring a bell...

I have a bisect for an ext4 issue in v6.1 which comes out at:

# first bad commit: [29897d75d6491ffe23cdc9d96caba9282a20dfc3] ext4: convert bd_bitmap_page to bd_bitmap_folio

For an oops which looks very similar (but on arm64):

[  217.347067] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000

...

[  217.567412] Call trace:
[  217.569884] ext4_mb_load_buddy_gfp (include/asm-generic/bitops/generic-non-atomic.h:128 include/linux/page-flags.h:719 fs/ext4/mballoc.c:1536)
[  217.574388] ext4_discard_preallocations (fs/ext4/mballoc.c:5137)
[  217.579421] ext4_release_file (fs/ext4/file.c:167 (discriminator 1))
[  217.583396] __fput (fs/file_table.c:321 (discriminator 1))
[  217.586490] ____fput (fs/file_table.c:349)
[  217.589671] task_work_run (kernel/task_work.c:206 (discriminator 1))
[  217.593294] do_notify_resume (include/linux/resume_user_mode.h:49 arch/arm64/kernel/signal.c:1151)
[  217.597358] el0_svc (arch/arm64/kernel/entry-common.c:639)
[  217.600452] el0t_64_sync_handler (arch/arm64/kernel/entry-common.c:656)
[  217.604866] el0t_64_sync (arch/arm64/kernel/entry.S:585)

Full log:

   https://lava.sirena.org.uk/scheduler/job/2595460#L3223

vmlinux:

   https://builds.sirena.org.uk/67c872a868ac98d7af3b5598c399eec173c1eb03/arm64/defconfig/vmlinux.xz

Full bisect log:

# bad: [67c872a868ac98d7af3b5598c399eec173c1eb03] Linux 6.1.167-rc1
# good: [f2ddafa93a259310ca47507153b7811ec54ab7fd] Linux 6.1.166
git bisect start '67c872a868ac98d7af3b5598c399eec173c1eb03' 'f2ddafa93a259310ca47507153b7811ec54ab7fd'
# test job: [67c872a868ac98d7af3b5598c399eec173c1eb03] https://lava.sirena.org.uk/scheduler/job/2595460
# bad: [67c872a868ac98d7af3b5598c399eec173c1eb03] Linux 6.1.167-rc1
git bisect bad 67c872a868ac98d7af3b5598c399eec173c1eb03
# test job: [19577ea2af78e1668d2dd7dd8ff49329363c8de6] https://lava.sirena.org.uk/scheduler/job/2596565
# bad: [19577ea2af78e1668d2dd7dd8ff49329363c8de6] parisc: Increase initial mapping to 64 MB with KALLSYMS
git bisect bad 19577ea2af78e1668d2dd7dd8ff49329363c8de6
# test job: [525e916e0f088809ef9111088480f7271d0c63cb] https://lava.sirena.org.uk/scheduler/job/2596655
# bad: [525e916e0f088809ef9111088480f7271d0c63cb] octeon_ep: avoid compiler and IQ/OQ reordering
git bisect bad 525e916e0f088809ef9111088480f7271d0c63cb
# test job: [be91f915a7a7e3c089fe5edaaae047dfed585492] https://lava.sirena.org.uk/scheduler/job/2596752
# bad: [be91f915a7a7e3c089fe5edaaae047dfed585492] usb: cdns3: remove redundant if branch
git bisect bad be91f915a7a7e3c089fe5edaaae047dfed585492
# test job: [7aaacb29d6420a3d9b09386545ee2d3afb5df5f3] https://lava.sirena.org.uk/scheduler/job/2596861
# good: [7aaacb29d6420a3d9b09386545ee2d3afb5df5f3] media: tegra-video: Use accessors for pad config 'try_*' fields
git bisect good 7aaacb29d6420a3d9b09386545ee2d3afb5df5f3
# test job: [d21133e5855b8a332718992df631a151276b3a93] https://lava.sirena.org.uk/scheduler/job/2596893
# good: [d21133e5855b8a332718992df631a151276b3a93] ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1
git bisect good d21133e5855b8a332718992df631a151276b3a93
# test job: [fe80bba8f76f9f0995cdc64fc89b65173e1ae828] https://lava.sirena.org.uk/scheduler/job/2596923
# bad: [fe80bba8f76f9f0995cdc64fc89b65173e1ae828] ext4: convert bd_buddy_page to bd_buddy_folio
git bisect bad fe80bba8f76f9f0995cdc64fc89b65173e1ae828
# test job: [b41ad91ef08bd65607929c01da58a745c52f099a] https://lava.sirena.org.uk/scheduler/job/2596982
# good: [b41ad91ef08bd65607929c01da58a745c52f099a] ext4: remove unnecessary e4b->bd_buddy_page check in ext4_mb_load_buddy_gfp
git bisect good b41ad91ef08bd65607929c01da58a745c52f099a
# test job: [500bdda4b7db98fc1f979670924696d7ce449124] https://lava.sirena.org.uk/scheduler/job/2597035
# good: [500bdda4b7db98fc1f979670924696d7ce449124] ext4: delete redundant calculations in ext4_mb_get_buddy_page_lock()
git bisect good 500bdda4b7db98fc1f979670924696d7ce449124
# test job: [29897d75d6491ffe23cdc9d96caba9282a20dfc3] https://lava.sirena.org.uk/scheduler/job/2597064
# bad: [29897d75d6491ffe23cdc9d96caba9282a20dfc3] ext4: convert bd_bitmap_page to bd_bitmap_folio
git bisect bad 29897d75d6491ffe23cdc9d96caba9282a20dfc3
# first bad commit: [29897d75d6491ffe23cdc9d96caba9282a20dfc3] ext4: convert bd_bitmap_page to bd_bitmap_folio

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