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Harding" To: Matthew Wilcox Cc: Roman Gushchin , "Tobin C. Harding" , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 0/4] mm: Use slab_list list_head instead of lru Message-ID: <20190312010554.GA9362@eros.localdomain> References: <20190311010744.5862-1-tobin@kernel.org> <20190311204919.GA20002@tower.DHCP.thefacebook.com> <20190311231633.GF19508@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190311231633.GF19508@bombadil.infradead.org> X-Mailer: Mutt 1.11.3 (2019-02-01) User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 11, 2019 at 04:16:33PM -0700, Matthew Wilcox wrote: > On Mon, Mar 11, 2019 at 08:49:23PM +0000, Roman Gushchin wrote: > > The patchset looks good to me, however I'd add some clarifications > > why switching from lru to slab_list is safe. > > > > My understanding is that the slab_list fields isn't currently in use, > > but it's not that obvious that putting slab_list and next/pages/pobjects > > fields into a union is safe (for the slub case). > > It's already in a union. > > struct page { > union { > struct { /* Page cache and anonymous pages */ > struct list_head lru; > ... > struct { /* slab, slob and slub */ > union { > struct list_head slab_list; /* uses lru */ > struct { /* Partial pages */ > struct page *next; > > slab_list and lru are in the same bits. Once this patch set is in, > we can remove the enigmatic 'uses lru' comment that I added. Funny you should say this, I came to me today while daydreaming that I should have removed that comment :) I'll remove it in v2. thanks, Tobin.