On 2019/09/30 9:28, Sasha Levin wrote: > On Sun, Sep 29, 2019 at 11:43:38PM +0900, Tetsuo Handa wrote: >> 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. > > We had a revert in the stable trees, but that revert was incorrect. > > Take a look at commit 513e1073d52e55 upstream, it patches > __lock_set_class() (even though the subject line says > __lock_downgrade()). So this is not a backporting error as the revert > said it is, but is rather the intended location to be patched. > > If this is actually wrong, then it should be addressed upstream first. > Hmm, upstream has two commits with same author, same date, same subject, different hash, different content. I couldn't find from https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@xxxxxxxxxx that we want to patch both __lock_set_class() and __lock_downgrade(), but I found that the tip-bot has patched __lock_downgrade() on "2019-01-21 11:29" and __lock_set_class() on "2019-02-04 8:56". Seems that we by error patched both functions, though patching both functions should be harmless... 64aa348ed kernel/lockdep.c (Peter Zijlstra 2008-08-11 09:30:21 +0200 4115) static int 00ef9f734 kernel/lockdep.c (Peter Zijlstra 2008-12-04 09:00:17 +0100 4116) __lock_set_class(struct lockdep_map *lock, const char *name, 00ef9f734 kernel/lockdep.c (Peter Zijlstra 2008-12-04 09:00:17 +0100 4117) struct lock_class_key *key, unsigned int subclass, 00ef9f734 kernel/lockdep.c (Peter Zijlstra 2008-12-04 09:00:17 +0100 4118) unsigned long ip) 64aa348ed kernel/lockdep.c (Peter Zijlstra 2008-08-11 09:30:21 +0200 4119) { 64aa348ed kernel/lockdep.c (Peter Zijlstra 2008-08-11 09:30:21 +0200 4120) struct task_struct *curr = current; 8c8889d8e kernel/locking/lockdep.c (Imre Deak 2019-05-24 23:15:08 +0300 4121) unsigned int depth, merged = 0; 41c2c5b86 kernel/locking/lockdep.c (J. R. Okajima 2017-02-03 01:38:15 +0900 4122) struct held_lock *hlock; 64aa348ed kernel/lockdep.c (Peter Zijlstra 2008-08-11 09:30:21 +0200 4123) struct lock_class *class; 64aa348ed kernel/lockdep.c (Peter Zijlstra 2008-08-11 09:30:21 +0200 4124) int i; 64aa348ed kernel/lockdep.c (Peter Zijlstra 2008-08-11 09:30:21 +0200 4125) 513e1073d kernel/locking/lockdep.c (Waiman Long 2019-01-09 23:03:25 -0500 4126) if (unlikely(!debug_locks)) 513e1073d kernel/locking/lockdep.c (Waiman Long 2019-01-09 23:03:25 -0500 4127) return 0; 513e1073d kernel/locking/lockdep.c (Waiman Long 2019-01-09 23:03:25 -0500 4128) 6419c4af7 kernel/locking/lockdep.c (J. R. Okajima 2017-02-03 01:38:17 +0900 4162) static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) 6419c4af7 kernel/locking/lockdep.c (J. R. Okajima 2017-02-03 01:38:17 +0900 4163) { 6419c4af7 kernel/locking/lockdep.c (J. R. Okajima 2017-02-03 01:38:17 +0900 4164) struct task_struct *curr = current; 8c8889d8e kernel/locking/lockdep.c (Imre Deak 2019-05-24 23:15:08 +0300 4165) unsigned int depth, merged = 0; 6419c4af7 kernel/locking/lockdep.c (J. R. Okajima 2017-02-03 01:38:17 +0900 4166) struct held_lock *hlock; 6419c4af7 kernel/locking/lockdep.c (J. R. Okajima 2017-02-03 01:38:17 +0900 4167) int i; 6419c4af7 kernel/locking/lockdep.c (J. R. Okajima 2017-02-03 01:38:17 +0900 4168) 714925805 kernel/locking/lockdep.c (Waiman Long 2019-01-09 23:03:25 -0500 4169) if (unlikely(!debug_locks)) 714925805 kernel/locking/lockdep.c (Waiman Long 2019-01-09 23:03:25 -0500 4170) return 0; 714925805 kernel/locking/lockdep.c (Waiman Long 2019-01-09 23:03:25 -0500 4171) commit 513e1073d52e55b8024b4f238a48de7587c64ccf Author: Waiman Long <longman@xxxxxxxxxx> Date: Wed Jan 9 23:03:25 2019 -0500 locking/lockdep: Add debug_locks check in __lock_downgrade() commit 71492580571467fb7177aade19c18ce7486267f5 Author: Waiman Long <longman@xxxxxxxxxx> Date: Wed Jan 9 23:03:25 2019 -0500 locking/lockdep: Add debug_locks check in __lock_downgrade()
