linux-kernel - Re: [PATCH v3] slub: fix false-positive lockdep warning in free

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Message-ID: <alpine.DEB.2.02.1402051324370.14325@chino.kir.corp.google.com>
Date:	Wed, 5 Feb 2014 13:25:28 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Steven Rostedt <rostedt@...dmis.org>
cc:	Vladimir Davydov <vdavydov@...allels.com>,
	akpm@...ux-foundation.org, penberg@...nel.org, cl@...ux.com,
	linux-kernel@...r.kernel.org, a.p.zijlstra@...llo.nl
Subject: Re: [PATCH v3] slub: fix false-positive lockdep warning in
 free_partial()

On Wed, 5 Feb 2014, Steven Rostedt wrote:

> Then add the comment that clears this up. But lets not add spinlocks
> just to quiet something if they truly are not needed.
> 
> We use "__" variants all the time. That's really not extra code.
> 
> Heck, if you want, call it remove_freed_partial() that shows that this
> version skips the check because it is freed.
> 
> And if you don't want to have remove_freed_partial() being called by
> remove_partial() than still keep the "__" variant, add a
> "__always_inline" to it, and then do:
> 
> static __always_inline
> __remove_partial(struct kmem_cache_node *n, struct page *page)
> {
>         list_del(&page->lru);
>         n->nr_partial--;
> }
> 
> static inline remove_partial(struct kmem_cache_node *n,
>                              struct page *page)
> {
>         lockdep_assert_held(&n->list_lock);
>         __remove_partial(n, page);
> }
> 
> 
> static inline remove_freed_partial(struct kmem_cache_node *n,
>                              struct page *page)
> {
>         __remove_partial(n, page);
> }
> 
> The naming like this documents itself.
> 

Looks like you've got something prepared already!  Mind sending it to 
Pekka as a patch based on linux-next?
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