From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f174.google.com (mail-pd0-f174.google.com [209.85.192.174]) by kanga.kvack.org (Postfix) with ESMTP id 5A3336B003A for ; Fri, 3 Jan 2014 13:02:12 -0500 (EST) Received: by mail-pd0-f174.google.com with SMTP id x10so15510070pdj.19 for ; Fri, 03 Jan 2014 10:02:12 -0800 (PST) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTP id qy2si15290085pbb.202.2014.01.03.10.02.09 for ; Fri, 03 Jan 2014 10:02:10 -0800 (PST) Subject: [PATCH 4/9] mm: slabs: reset page at free From: Dave Hansen Date: Fri, 03 Jan 2014 10:01:55 -0800 References: <20140103180147.6566F7C1@viggo.jf.intel.com> In-Reply-To: <20140103180147.6566F7C1@viggo.jf.intel.com> Message-Id: <20140103180155.BAF4FECF@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, penberg@kernel.org, cl@linux-foundation.org, Dave Hansen From: Dave Hansen In order to simplify 'struct page', we will shortly be moving some fields around. This causes slub's ->freelist usage to impinge on page->mapping's storage space. The buddy allocator wants ->mapping to be NULL when a page is handed back, so we have to make sure that it is cleared. Note that slab already doeds this, so just create a common helper and have all the slabs do it this way. ->mapping is right next to ->flags, so it's virtually guaranteed to be in the L1 at this point, so this shouldn't cost very much to do in practice. Other allocators and users of 'struct page' may also want to call this if they use parts of 'struct page' for nonstandard purposes. Signed-off-by: Dave Hansen --- linux.git-davehans/include/linux/mm.h | 11 +++++++++++ linux.git-davehans/mm/slab.c | 3 +-- linux.git-davehans/mm/slob.c | 2 +- linux.git-davehans/mm/slub.c | 2 +- 4 files changed, 14 insertions(+), 4 deletions(-) diff -puN include/linux/mm.h~slub-reset-page-at-free include/linux/mm.h --- linux.git/include/linux/mm.h~slub-reset-page-at-free 2014-01-02 13:40:30.057300388 -0800 +++ linux.git-davehans/include/linux/mm.h 2014-01-02 13:40:30.067300838 -0800 @@ -2028,5 +2028,16 @@ static inline void set_page_pfmemalloc(s page->index = pfmemalloc; } +/* + * Custom allocators (like the slabs) use 'struct page' fields + * for all kinds of things. This resets the page's state so that + * the buddy allocator will be happy with it. + */ +static inline void allocator_reset_page(struct page *page) +{ + page->mapping = NULL; + page_mapcount_reset(page); +} + #endif /* __KERNEL__ */ #endif /* _LINUX_MM_H */ diff -puN mm/slab.c~slub-reset-page-at-free mm/slab.c --- linux.git/mm/slab.c~slub-reset-page-at-free 2014-01-02 13:40:30.060300523 -0800 +++ linux.git-davehans/mm/slab.c 2014-01-02 13:40:30.069300928 -0800 @@ -1718,8 +1718,7 @@ static void kmem_freepages(struct kmem_c BUG_ON(!PageSlab(page)); __ClearPageSlabPfmemalloc(page); __ClearPageSlab(page); - page_mapcount_reset(page); - page->mapping = NULL; + allocator_reset_page(page); memcg_release_pages(cachep, cachep->gfporder); if (current->reclaim_state) diff -puN mm/slob.c~slub-reset-page-at-free mm/slob.c --- linux.git/mm/slob.c~slub-reset-page-at-free 2014-01-02 13:40:30.061300568 -0800 +++ linux.git-davehans/mm/slob.c 2014-01-02 13:40:30.070300973 -0800 @@ -360,7 +360,7 @@ static void slob_free(void *block, int s clear_slob_page_free(sp); spin_unlock_irqrestore(&slob_lock, flags); __ClearPageSlab(sp); - page_mapcount_reset(sp); + allocator_reset_page(sp); slob_free_pages(b, 0); return; } diff -puN mm/slub.c~slub-reset-page-at-free mm/slub.c --- linux.git/mm/slub.c~slub-reset-page-at-free 2014-01-02 13:40:30.063300658 -0800 +++ linux.git-davehans/mm/slub.c 2014-01-02 13:40:30.071301017 -0800 @@ -1452,7 +1452,7 @@ static void __free_slab(struct kmem_cach __ClearPageSlab(page); memcg_release_pages(s, order); - page_mapcount_reset(page); + allocator_reset_page(page); if (current->reclaim_state) current->reclaim_state->reclaimed_slab += pages; __free_memcg_kmem_pages(page, order); _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org