From: Matthew Wilcox <willy@infradead.org> To: linux-mm@kvack.org Cc: "Matthew Wilcox" <mawilcox@microsoft.com>, "Andrew Morton" <akpm@linux-foundation.org>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, "Christoph Lameter" <cl@linux.com>, "Lai Jiangshan" <jiangshanlai@gmail.com>, "Pekka Enberg" <penberg@kernel.org>, "Vlastimil Babka" <vbabka@suse.cz>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Jérôme Glisse" <jglisse@redhat.com> Subject: [PATCH v5 06/17] mm: Move _refcount out of struct page union Date: Fri, 4 May 2018 11:33:07 -0700 [thread overview] Message-ID: <20180504183318.14415-7-willy@infradead.org> (raw) In-Reply-To: <20180504183318.14415-1-willy@infradead.org> From: Matthew Wilcox <mawilcox@microsoft.com> Keeping the refcount in the union only encourages people to put something else in the union which will overlap with _refcount and eventually explode messily. pahole reports no fields change location. Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- include/linux/mm_types.h | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 23378a789af4..9828cd170251 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -113,7 +113,13 @@ struct page { }; }; - union { + union { /* This union is 4 bytes in size. */ + /* + * If the page can be mapped to userspace, encodes the number + * of times this page is referenced by a page table. + */ + atomic_t _mapcount; + /* * If the page is neither PageSlab nor mappable to userspace, * the value stored here may help determine what this page @@ -124,22 +130,11 @@ struct page { unsigned int active; /* SLAB */ int units; /* SLOB */ - - struct { /* Page cache */ - /* - * Count of ptes mapped in mms, to show when - * page is mapped & limit reverse map searches. - */ - atomic_t _mapcount; - - /* - * Usage count, *USE WRAPPER FUNCTION* when manual - * accounting. See page_ref.h - */ - atomic_t _refcount; - }; }; + /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */ + atomic_t _refcount; + /* * WARNING: bit 0 of the first word encode PageTail(). That means * the rest users of the storage space MUST NOT use the bit to -- 2.17.0
next prev parent reply other threads:[~2018-05-04 18:33 UTC|newest] Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-04 18:33 [PATCH v5 00/17] Rearrange struct page Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 01/17] s390: Use _refcount for pgtables Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 02/17] mm: Split page_type out from _mapcount Matthew Wilcox 2018-05-14 14:33 ` Vlastimil Babka 2018-05-04 18:33 ` [PATCH v5 03/17] mm: Mark pages in use for page tables Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 04/17] mm: Switch s_mem and slab_cache in struct page Matthew Wilcox 2018-05-07 14:58 ` Christopher Lameter 2018-05-14 14:37 ` Vlastimil Babka 2018-05-04 18:33 ` [PATCH v5 05/17] mm: Move 'private' union within " Matthew Wilcox 2018-05-04 18:33 ` Matthew Wilcox [this message] 2018-05-04 18:33 ` [PATCH v5 07/17] mm: Combine first three unions in " Matthew Wilcox 2018-05-14 14:42 ` Vlastimil Babka 2018-05-04 18:33 ` [PATCH v5 08/17] mm: Use page->deferred_list Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 09/17] mm: Move lru union within struct page Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 10/17] mm: Combine LRU and main union in " Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 11/17] mm: Improve struct page documentation Matthew Wilcox 2018-05-15 9:22 ` Vlastimil Babka 2018-05-04 18:33 ` [PATCH v5 12/17] mm: Add pt_mm to struct page Matthew Wilcox 2018-05-15 9:27 ` Vlastimil Babka 2018-05-15 12:23 ` Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 13/17] mm: Add hmm_data " Matthew Wilcox 2018-05-15 9:32 ` Vlastimil Babka 2018-05-15 12:40 ` Vlastimil Babka 2018-05-04 18:33 ` [PATCH v5 14/17] slab,slub: Remove rcu_head size checks Matthew Wilcox 2018-05-15 11:30 ` Vlastimil Babka 2018-05-04 18:33 ` [PATCH v5 15/17] slub: Remove kmem_cache->reserved Matthew Wilcox 2018-05-04 18:33 ` [PATCH v5 16/17] slub: Remove 'reserved' file from sysfs Matthew Wilcox 2018-05-07 15:01 ` Christopher Lameter 2018-05-04 18:33 ` [PATCH v5 17/17] mm: Distinguish VMalloc pages Matthew Wilcox 2018-05-04 20:52 ` [PATCH v5 00/17] Rearrange struct page Andrew Morton 2018-05-04 21:25 ` Matthew Wilcox
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20180504183318.14415-7-willy@infradead.org \ --to=willy@infradead.org \ --cc=akpm@linux-foundation.org \ --cc=cl@linux.com \ --cc=dave.hansen@linux.intel.com \ --cc=jglisse@redhat.com \ --cc=jiangshanlai@gmail.com \ --cc=kirill.shutemov@linux.intel.com \ --cc=linux-mm@kvack.org \ --cc=mawilcox@microsoft.com \ --cc=penberg@kernel.org \ --cc=vbabka@suse.cz \ --subject='Re: [PATCH v5 06/17] mm: Move _refcount out of struct page union' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.