On Mon, Mar 21, 2016 at 09:40:16AM -0500, Josh Cartwright wrote:
| On Sat, Mar 19, 2016 at 09:33:34AM +0100, Thomas Gleixner wrote:
| > On Mon, 14 Mar 2016, Luis Claudio R. Goncalves wrote:
| >
| > > Hello,
| > >
| > > I just started using 4.4.4-rt11 this afternoon and saw the lockdep splat below.
| > > Is this something new or did I miss a patch floating on the list?
| >
| > That's new. Looking into it.
|
| It looks like the way that INIT_HLIST_BL_HEAD() is authored, all
| instances of the contained raw spinlock will share the same lockdep
| class. That, coupled with the following in mb_cache_shrink(), is
| triggering the lockdep violation:
|
| void
| mb_cache_shrink(struct block_device *bdev)
| {
| [..]
| /*
| * Prevent any find or get operation on the entry.
| */
| hlist_bl_lock(ce->e_block_hash_p);
| hlist_bl_lock(ce->e_index_hash_p);
|
| Josh
Josh, I built a kernel with your patch and the lockdep complaint is gone.
I was used to see the message within 30 minutes of normal usage. So far,
four hours with that kernel running and no complaints.
Tested-by: Luis Claudio R. Goncalves <lclaudio@xxxxxxxx>
Thanks!
Luis
| diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
| index 44f0b55..d13428a 100644
| --- a/include/linux/list_bl.h
| +++ b/include/linux/list_bl.h
| @@ -42,13 +42,18 @@ struct hlist_bl_node {
| struct hlist_bl_node *next, **pprev;
| };
|
| -static inline void INIT_HLIST_BL_HEAD(struct hlist_bl_head *h)
| -{
| - h->first = NULL;
| #ifdef CONFIG_PREEMPT_RT_BASE
| - raw_spin_lock_init(&h->lock);
| +#define INIT_HLIST_BL_HEAD(h) \
| +do { \
| + (h)->first = NULL; \
| + raw_spin_lock_init(&(h)->lock); \
| +} while (0)
| +#else
| +#define INIT_HLIST_BL_HEAD(h) \
| +do { \
| + (h)->first = NULL; \
| +} while (0)
| #endif
| -}
|
| static inline void INIT_HLIST_BL_NODE(struct hlist_bl_node *h)
| {
---end quoted text---
--
[ Luis Claudio R. Goncalves Bass - Gospel - RT ]
[ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9 2696 7203 D980 A448 C8F8 ]
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