Re: linux-next: build failure after merge of the tip tree

[Mark Brown]

On Tue, Mar 10, 2026 at 06:28:30PM +0000, Mark Brown wrote:
> Hi all,
> 
> After merging the tip tree, today's linux-next started crashing running
> arm64 KUnit like this:
> 
> [18:12:16] [PASSED] split unwrit extent to 3 extents and convert 2nd half writ (non-endio, zeroout) (highlevel)
> [18:12:16] =============== [PASSED] test_split_convert ================
> [18:12:16] ================ [PASSED] ext4_extents_test ================
> [18:12:16] ============== ext4_mballoc_test (7 subtests) ==============
> Command '['qemu-system-aarch64', '-nodefaults', '-m', '1024', '-kernel', '/tmp/next/arm64_kunit/arch/arm64/boot/Image.gz', '-append', 'kunit.enable=1 console=ttyAMA0 kunit_shutdown=reboot', '-no-reboot', '-nographic', '-accel', 'kvm', '-accel', 'hvf', '-accel', 'tcg', '-serial', 'stdio', '-machine', 'virt', '-cpu', 'max']' timed out after 300 seconds
> 
> I didn't figure out what the source of the issue was, I merged the tip
> tree from 20260309 instead.

I tried to leave a bisect running but it got confused because a lot of
the branches are based on v7.0-rc1 which has a separate bug that causes
KUnit to lock up so the results are nonsense.  I did confirm an issue
with just tip/master.  My KUnit command line running on current Debian
stable is:

    ./tools/testing/kunit/kunit.py run --alltests --arch arm64 --cross_compile=aarch64-linux-gnu-

and I also tried:

    ./tools/testing/kunit/kunit.py run --alltests --arch x86_64 --cross_compile=x86_64-linux-gnu-

and got:

[23:51:03] [PASSED] split unwrit extent to 3 extents and convert 2nd half writ (non-endio, zeroout) (highlevel)
[23:51:03] =============== [PASSED] test_split_convert ================
[23:51:03] ================ [PASSED] ext4_extents_test ================
[23:51:03] ============== ext4_mballoc_test (7 subtests) ==============
[23:51:03] ================= test_new_blocks_simple  ==================
[23:51:03] [FAILED] block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64

before the deadlock which looks awfully similar, though it does make a
bit more progress and gives a crash:

[23:55:51] [ERROR] Test: test_new_blocks_simple: missing subtest result line!
[23:55:51] BUG: unable to handle page fault for address: 00000008bcf958c7
[23:55:51] #PF: supervisor write access in kernel mode
[23:55:51] #PF: error_code(0x0002) - not-present page

...

[23:58:45] Call Trace:
[23:58:45] <TASK>
[23:58:45] ext4_mb_release (??:?)
[23:58:45] mbt_kunit_exit (mballoc.c:?)
[23:58:45] ? __pfx_kunit_generic_run_threadfn_adapter (try-catch.c:?)
[23:58:45] kunit_try_run_case_cleanup (test.c:?)
[23:58:45] kunit_generic_run_threadfn_adapter (try-catch.c:?)
[23:58:45] kthread (kthread.c:?)
[23:58:45] ? __pfx_kthread (kthread.c:?)
[23:58:45] ret_from_fork (??:?)
[23:58:45] ? __pfx_kthread (kthread.c:?)
[23:58:45] ret_from_fork_asm (??:?)

plus subsequent things that look like aftereffects of the same thing.

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