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Message-Id: <3ec48fde01e4ee6505f77908ba351bad200ae3d1.1694763684.git.lukas@wunner.de>
Date: Wed, 15 Sep 2023 09:55:39 +0200
From: Lukas Wunner <lukas@...ner.de>
To: Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] panic: Reenable preemption in WARN slowpath
Commit 5a5d7e9badd2 ("cpuidle: lib/bug: Disable rcu_is_watching() during
WARN/BUG") amended warn_slowpath_fmt() to disable preemption until the
WARN splat has been emitted.
However the commit neglected to reenable preemption in the !fmt codepath,
i.e. when a WARN splat is emitted without additional format string.
One consequence is that users may see more splats than intended. E.g. a
WARN splat emitted in a work item results in at least two extra splats:
BUG: workqueue leaked lock or atomic
(emitted by process_one_work())
BUG: scheduling while atomic
(emitted by worker_thread() -> schedule())
Ironically the point of the commit was to *avoid* extra splats. ;)
Fix it.
Fixes: 5a5d7e9badd2 ("cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG")
Signed-off-by: Lukas Wunner <lukas@...ner.de>
Cc: stable@...r.kernel.org # v6.1+
Cc: Peter Zijlstra <peterz@...radead.org>
---
The original commit went in through the tip tree, hence submitting to
tip maintainers. The commit was backported to v6.1-stable (even though
it wasn't tagged for stable), hence this fix needs a stable designation.
kernel/panic.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/panic.c b/kernel/panic.c
index 07239d4..ffa037fa 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -697,6 +697,7 @@ void warn_slowpath_fmt(const char *file, int line, unsigned taint,
if (!fmt) {
__warn(file, line, __builtin_return_address(0), taint,
NULL, NULL);
+ warn_rcu_exit(rcu);
return;
}
--
2.39.2
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