On 16.07.24 07:37, Borah, Chaitanya Kumar wrote:
Hello Pei,
Hope you are doing well. I am Chaitanya from the linux graphics team in Intel.
This mail is regarding a regression we are seeing in our CI runs[1] on linux-next repository.
In version next-20240712[2], we saw the following regression (currently being masked by another regression)
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<4>[ 14.530533] ============================================
<4>[ 14.530533] WARNING: possible recursive locking detected
<4>[ 14.530534] 6.10.0-rc7-next-20240712-next-20240712-g3fe121b62282+ #1 Not tainted
<4>[ 14.530535] --------------------------------------------
<4>[ 14.530535] (direxec)/171 is trying to acquire lock:
<4>[ 14.530536] ffff8881010725d8 (&mm->mmap_lock){++++}-{3:3}, at: unmap_single_vma+0xea/0x170
<4>[ 14.530541]
but task is already holding lock:
<4>[ 14.530542] ffff8881010725d8 (&mm->mmap_lock){++++}-{3:3}, at: exit_mmap+0x6a/0x450
<4>[ 14.530545]
other info that might help us debug this:
<4>[ 14.530545] Possible unsafe locking scenario:
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Details log can be found in [3].
After bisecting the tree, the following patch [4] seems to be the first "bad"
commit
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commit a13252049629a8225f38a9be7d8d4fc4ff5350e8
Author: Pei Li mailto:peili.dev@xxxxxxxxx
Date: Wed Jul 10 22:13:17 2024 -0700
mm: fix mmap_assert_locked() in follow_pte()
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We also verified that if we revert the patch the issue is not seen.
Could you please check why the patch causes this regression and provide a fix if necessary?
This is know.
There is a discussion along the original patch [1] on how to do it
differently. But likely we'll tackle it differently [2]. So this patch
should be dropped for -- which I think already happened because I cannot
spot that patch in mm-unstable anymore.
[1] https://lore.kernel.org/all/20240710-bug12-v1-1-0e5440f9b8d3@xxxxxxxxx/
[2] https://lkml.kernel.org/r/20240712144244.3090089-1-peterx@xxxxxxxxxx
--
Cheers,
David / dhildenb
