Re: [driver-core:debugfs_lookup_fix] [mm/damon/dbgfs] ff25f87cfc: kernel_BUG_at_lib/list_debug.c

[SeongJae Park <sj@kernel.org>]

Hello,

On Tue, 3 Jan 2023 21:16:09 +0800 kernel test robot <oliver.sang@intel.com> wrote:

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> 
> 
> Greeting,
> 
> FYI, we noticed kernel_BUG_at_lib/list_debug.c due to commit (built with gcc-11):

Thank you for the report!

> 
> commit: ff25f87cfcfc34ebe652987f2a7beb184762785b ("mm/damon/dbgfs: fix memory leak when using debugfs_lookup()")
> https://git.kernel.org/cgit/linux/kernel/git/gregkh/driver-core.git debugfs_lookup_fix

The commit is for fixing a memory leak due to missed dput() call.  The patch
has posted originally by Greg and revised my I[1].  The revised version has
merged in mainline during v6.0 stabilization period (1552fd3ef7db).

The problematic tree (driver-core/debugfs_lookup_fix) is based on v6.2-rc2, so
the revised patch is already applied.  But the first version of the patch is
applied again on the tree[2], probably by mistake, and caused double 'dput()'.

So I think the commit seems needs to be reverted.

If there is anything I missed or wrong, please let me know.

[1] https://lore.kernel.org/damon/20220902191149.112434-1-sj@kernel.org/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git/commit/?h=debugfs_lookup_fix&id=5167d3e8149e332204274910da1057e8f907d7d2


Thanks,
SJ