linux-kernel - Re: [PATCH v2] mm/slub: Run free_partial() outside of the kmem_cache_node->list

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Message-ID: <20160809160612.GH1983@esperanza>
Date:	Tue, 9 Aug 2016 19:06:12 +0300
From:	Vladimir Davydov <vdavydov@...tuozzo.com>
To:	Chris Wilson <chris@...is-wilson.co.uk>
CC:	<linux-kernel@...r.kernel.org>, Christoph Lameter <cl@...ux.com>,
	"Pekka Enberg" <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	"Joonsoo Kim" <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dmitry Safonov <dsafonov@...tuozzo.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Dave Gordon <david.s.gordon@...el.com>, <linux-mm@...ck.org>
Subject: Re: [PATCH v2] mm/slub: Run free_partial() outside of the
 kmem_cache_node->list_lock

On Tue, Aug 09, 2016 at 04:52:13PM +0100, Chris Wilson wrote:
...
> > > @@ -3486,13 +3487,16 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
> > >  	list_for_each_entry_safe(page, h, &n->partial, lru) {
> > >  		if (!page->inuse) {
> > >  			remove_partial(n, page);
> > > -			discard_slab(s, page);
> > > +			list_add(&page->lru, &partial_list);
> > 
> > If there are objects left in the cache on destruction, the cache won't
> > be destroyed. Instead it will be left on the slab_list and can get
> > reused later. So we should use list_move() here to always leave
> > n->partial in a consistent state, even in case of a leak.
> 
> Since remove_partial() does an unconditional list_del(),
> I presume you want to perform the list_move() even if we hit the error
> path, right?

Please ignore my previous remark - I missed that remove_partial() does
list_del(), so using list_add(), as you did in v2, should be just fine.
Feel free, to add

Reviewed-by: Vladimir Davydov <vdavydov@...tuozzo.com>

Thanks,
Vladimir