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From: Matthew Wilcox <willy@infradead.org>
To: Roman Gushchin <guro@fb.com>
Cc: "Tobin C. Harding" <tobin@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/4] mm: Use slab_list list_head instead of lru
Date: Mon, 11 Mar 2019 16:16:33 -0700	[thread overview]
Message-ID: <20190311231633.GF19508@bombadil.infradead.org> (raw)
In-Reply-To: <20190311204919.GA20002@tower.DHCP.thefacebook.com>

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.


  reply	other threads:[~2019-03-11 23:16 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-11  1:07 Tobin C. Harding
2019-03-11  1:07 ` [PATCH 1/4] slub: Add comments to endif pre-processor macros Tobin C. Harding
2019-03-11  1:07 ` [PATCH 2/4] slub: Use slab_list instead of lru Tobin C. Harding
2019-03-11  1:07 ` [PATCH 3/4] slab: " Tobin C. Harding
2019-03-11  1:07 ` [PATCH 4/4] slob: " Tobin C. Harding
2019-03-11 20:49 ` [PATCH 0/4] mm: Use slab_list list_head " Roman Gushchin
2019-03-11 23:16   ` Matthew Wilcox [this message]
2019-03-12  0:22     ` Roman Gushchin
2019-03-12  1:06       ` Tobin C. Harding
2019-03-12  2:01       ` Tobin C. Harding
2019-03-12 17:19         ` Roman Gushchin
2019-03-12  1:05     ` Tobin C. Harding
2019-03-12  2:38       ` Matthew Wilcox
2019-03-12  3:53         ` Tobin C. Harding
2019-03-12 17:22         ` Roman Gushchin

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