On 2019/09/29 22:54, Greg Kroah-Hartman wrote: > From: Waiman Long <longman@xxxxxxxxxx> > > [ Upstream commit 513e1073d52e55b8024b4f238a48de7587c64ccf ] > > Tetsuo Handa had reported he saw an incorrect "downgrading a read lock" > warning right after a previous lockdep warning. It is likely that the > previous warning turned off lock debugging causing the lockdep to have > inconsistency states leading to the lock downgrade warning. > > Fix that by add a check for debug_locks at the beginning of > __lock_downgrade(). Please drop "[PATCH 4.19 36/63] locking/lockdep: Add debug_locks check in __lock_downgrade()". We had a revert patch shown below in the past. "[PATCH 4.19 37/63] locking/lockdep: Add debug_locks check in __lock_downgrade() - again" seems the correct patch. On 2019/04/25 17:08, gregkh@xxxxxxxxxxxxxxxxxxx wrote:> > This is a note to let you know that I've just added the patch titled > > Revert "locking/lockdep: Add debug_locks check in __lock_downgrade()" > > to the 4.19-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > revert-locking-lockdep-add-debug_locks-check-in-__lock_downgrade.patch > and it can be found in the queue-4.19 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable@xxxxxxxxxxxxxxx> know about it. > > >>From 7f437eec35a20f40d9ff82ae1c072b211c29e8e0 Mon Sep 17 00:00:00 2001 > From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Date: Thu, 25 Apr 2019 10:00:43 +0200 > Subject: Revert "locking/lockdep: Add debug_locks check in __lock_downgrade()" > > From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > This reverts commit 0e0f7b30721233ce610bde2395a8e58ff7771475 which was > commit 71492580571467fb7177aade19c18ce7486267f5 upstream. > > Tetsuo rightly points out that the backport here is incorrect, as it > touches the __lock_set_class function instead of the intended > __lock_downgrade function. > > Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Cc: Waiman Long <longman@xxxxxxxxxx> > Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Will Deacon <will.deacon@xxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Sasha Levin <sashal@xxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > --- > kernel/locking/lockdep.c | 3 --- > 1 file changed, 3 deletions(-) > > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -3567,9 +3567,6 @@ __lock_set_class(struct lockdep_map *loc > unsigned int depth; > int i; > > - if (unlikely(!debug_locks)) > - return 0; > - > depth = curr->lockdep_depth; > /* > * This function is about (re)setting the class of a held lock, > >
