Hibernation: Fix lockdep report (v2)
Subsystems (2)
PATCH 1/1 Hibernation: Fix lockdep report (v2)
[Andrew, please consider this as 2.6.24 material, thanks.]
---
From: Johannes Berg <[email protected]>
Lockdep reports a circular locking dependency in the hibernate code because
- during system boot hibernate code (from an initcall) locks pm_mutex and then a sysfs buffer mutex via name_to_dev_t
- during regular operation hibernate code locks pm_mutex under a sysfs buffer mutex because it's called from sysfs methods.
The deadlock can never happen because during initcall invocation nothing can write to sysfs yet. This removes the lockdep report by marking the initcall locking as being in a different class.
--- kernel/power/disk.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
kernel/power/disk.c +11 -1
@@ -456,7 +456,17 @@ static int software_resume(void)int error;unsigned int flags; -mutex_lock (&pm_mutex); +/* +* name_to_dev_t() below takes a sysfs buffer mutex when sysfs +* is configured into the kernel. Since the regular hibernate +* trigger path is via sysfs which takes a buffer mutex before +* calling hibernate functions (which take pm_mutex) this can +* cause lockdep to complain about a possible ABBA deadlock +* which cannot happen since we're in the boot code here and +* sysfs can't be invoked yet. Therefore, we use a subclass +* here to avoid lockdep complaining. +*/ +mutex_lock_nested (&pm_mutex,SINGLE_DEPTH_NESTING );if (!swsusp_resume_device) {if (!strlen (resume_file)) {mutex_unlock (&pm_mutex);
Quoted 11 lines · Rafael J. Wysocki
[Andrew, please consider this as 2.6.24 material, thanks.]
---
From: Johannes Berg <[email protected]>Lockdep reports a circular locking dependency in the hibernate code because
- during system boot hibernate code (from an initcall) lockspm_mutexand then a sysfs buffer mutex vianame_to_dev_t
- during regular operation hibernate code lockspm_mutexunder a sysfs buffer mutex because it's called from sysfs methods.
Quoted 8 lines
The deadlock can never happen because during initcall invocation nothing can write to sysfs yet. This removes the lockdep report by marking the initcall locking as being in a different class.
Signed-off-by Johannes Berg <[email protected]>Cc Alan Stern <[email protected]>Cc Peter Zijlstra <[email protected]>Cc Pavel Machek <[email protected]>
ACK...
Signature · 2 lines
(english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
Peter Zijlstra
Acked-byQuoted 12 lines · Pavel Machek
Quoted 11 lines · Rafael J. Wysocki
[Andrew, please consider this as 2.6.24 material, thanks.]
---
From: Johannes Berg <[email protected]>Lockdep reports a circular locking dependency in the hibernate code because
- during system boot hibernate code (from an initcall) lockspm_mutexand then a sysfs buffer mutex vianame_to_dev_t
- during regular operation hibernate code lockspm_mutexunder a sysfs buffer mutex because it's called from sysfs methods.
Quoted 7 lines
Quoted 7 lines
The deadlock can never happen because during initcall invocation nothing can write to sysfs yet. This removes the lockdep report by marking the initcall locking as being in a different class.
Signed-off-by Johannes Berg <[email protected]>Cc Alan Stern <[email protected]>Cc Peter Zijlstra <[email protected]>
I guess mine got lost too :-)
Quoted 4 lines
Quoted 1 line
Cc Pavel Machek <[email protected]>ACK...
Peter Zijlstra
Acked-byQuoted 12 lines · Pavel Machek
Quoted 11 lines · Rafael J. Wysocki
[Andrew, please consider this as 2.6.24 material, thanks.]
---
From: Johannes Berg <[email protected]>Lockdep reports a circular locking dependency in the hibernate code because
- during system boot hibernate code (from an initcall) lockspm_mutexand then a sysfs buffer mutex vianame_to_dev_t
- during regular operation hibernate code lockspm_mutexunder a sysfs buffer mutex because it's called from sysfs methods.
Quoted 7 lines
Quoted 7 lines
The deadlock can never happen because during initcall invocation nothing can write to sysfs yet. This removes the lockdep report by marking the initcall locking as being in a different class.
Signed-off-by Johannes Berg <[email protected]>Cc Alan Stern <[email protected]>Cc Peter Zijlstra <[email protected]>
I guess mine got lost too :-)
Quoted 4 lines
Quoted 1 line
Cc Pavel Machek <[email protected]>ACK...
Quoted 11 lines · Rafael J. Wysocki
[Andrew, please consider this as 2.6.24 material, thanks.]
---
From: Johannes Berg <[email protected]>Lockdep reports a circular locking dependency in the hibernate code because
- during system boot hibernate code (from an initcall) lockspm_mutexand then a sysfs buffer mutex vianame_to_dev_t
- during regular operation hibernate code lockspm_mutexunder a sysfs buffer mutex because it's called from sysfs methods.
Quoted 8 lines
The deadlock can never happen because during initcall invocation nothing can write to sysfs yet. This removes the lockdep report by marking the initcall locking as being in a different class.
Signed-off-by Johannes Berg <[email protected]>Cc Alan Stern <[email protected]>Cc Peter Zijlstra <[email protected]>Cc Pavel Machek <[email protected]>
ACK...
Signature · 2 lines
(english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html