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: <syzbot+7f4a6f7f7051474e40ad@syzkaller.appspotmail.com>
Fixes: de8f5e4f2dc1f ("lockdep: Introduce wait-type checks")
Cc: stable@vger.kernel.org
Signed-off-by: Ahmed Ehab <bottaawesome633@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/lkml/20240824221031.7751-1-bottaawesome633@gmail.com/
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 7621350c6bb20fb6ab7eb988833ab96eac3dcbef ]
DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT can't be used when we hold locks
since we are basically waiting for userspace to do something.
Holding a lock while doing so can trivial deadlock with page faults
etc...
So make lockdep complain when a driver tries to do this.
v2: Add lockdep_assert_none_held() macro.
v3: Add might_sleep() and also use lockdep_assert_none_held() in the
IOCTL path.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patchwork.freedesktop.org/patch/414944/
Stable-dep-of: 3c43177ffb54 ("drm/syncobj: call drm_syncobj_fence_add_wait when WAIT_AVAILABLE flag is set")
Signed-off-by: Sasha Levin <sashal@kernel.org>
