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Date: Tue, 10 Apr 2018 15:47:28 -0500 (CDT)
From: Christopher Lameter <cl@linux.com>
Subject: Re: [PATCH] slub: Remove use of page->counter
In-Reply-To: <20180410195429.GB21336@bombadil.infradead.org>
Message-ID: <alpine.DEB.2.20.1804101545350.30437@nuc-kabylake>
References: <20180410195429.GB21336@bombadil.infradead.org>
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Sender: owner-linux-mm@kvack.org
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To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org

On Tue, 10 Apr 2018, Matthew Wilcox wrote:

> In my continued attempt to clean up struct page, I've got to the point
> where it'd be really nice to get rid of 'counters'.  I like the patch
> below because it makes it clear when & where we're doing "weird" things
> to access the various counters.

Well sounds good.

> struct {
> 	unsigned long flags;
> 	union {
> 		struct {
> 			struct address_space *mapping;
> 			pgoff_t index;
> 		};
> 		struct {
> 			void *s_mem;
> 			void *freelist;
> 		};
> 		...
> 	};
> 	union {
> 		atomic_t _mapcount;
> 		unsigned int active;

Is this aligned on a doubleword boundary? Maybe move the refcount below
the flags field?