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Ahmed Ehab authored
commit d7fe143cb115076fed0126ad8cf5ba6c3e575e43 upstream.

Syzbot reports a problem that a warning will be triggered while
searching a lock class in look_up_lock_class().

The cause of the issue is that a new name is created and used by
lockdep_set_subclass() instead of using the existing one. This results
in a lock instance has a different name pointer than previous registered
one stored in lock class, and WARN_ONCE() is triggered because of that
in look_up_lock_class().

To fix this, change lockdep_set_subclass() to use the existing name
instead of a new one. Hence, no new name will be created by
lockdep_set_subclass(). Hence, the warning is avoided.

[boqun: Reword the commit log to state the correct issue]

Reported-by: default avatar <syzbot+7f4a6f7f7051474e40ad@syzkaller.appspotmail.com>
Fixes: de8f5e4f ("lockdep: Introduce wait-type checks")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarAhmed Ehab <bottaawesome633@gmail.com>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/lkml/20240824221031.7751-1-bottaawesome633@gmail.com/


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
88232a22
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.