Re: Are jump labels broken on 6.11-rc1?

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Jul 30, 2024 at 01:00:02PM +0530, Chandan Babu R wrote:
> On Mon, Jul 29, 2024 at 08:38:49 PM -0700, Darrick J. Wong wrote:
> > Hi everyone,
> >
> > I got the following splat on 6.11-rc1 when I tried to QA xfs online
> > fsck.  Does this ring a bell for anyone?  I'll try bisecting in the
> > morning to see if I can find the culprit.
> 
> xfs/566 on v6.11-rc1 would consistently cause the oops mentioned below.
> However, I was able to get xfs/566 to successfully execute for five times on a
> v6.11-rc1 kernel with the following commits reverted,
> 
> 83ab38ef0a0b2407d43af9575bb32333fdd74fb2
> 695ef796467ed228b60f1915995e390aea3d85c6
> 9bc2ff871f00437ad2f10c1eceff51aaa72b478f
> 
> Reinstating commit 83ab38ef0a0b2407d43af9575bb32333fdd74fb2 causes the kernel
> to oops once again.

Durr, does this help?


diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 4ad5ed8adf96..57f70dfa1f3d 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -236,7 +236,7 @@ void static_key_disable_cpuslocked(struct static_key *key)
 	}
 
 	jump_label_lock();
-	if (atomic_cmpxchg(&key->enabled, 1, 0))
+	if (atomic_cmpxchg(&key->enabled, 1, 0) == 1)
 		jump_label_update(key);
 	jump_label_unlock();
 }