Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964985AbZGQR3L (ORCPT ); Fri, 17 Jul 2009 13:29:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934798AbZGQR3I (ORCPT ); Fri, 17 Jul 2009 13:29:08 -0400 Received: from mx2.redhat.com ([66.187.237.31]:49261 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934796AbZGQR3F (ORCPT ); Fri, 17 Jul 2009 13:29:05 -0400 From: Izik Eidus To: akpm@linux-foundation.org Cc: hugh.dickins@tiscali.co.uk, aarcange@redhat.com, chrisw@redhat.com, avi@redhat.com, riel@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, nickpiggin@yahoo.com.au, ieidus@redhat.com, Wu Fengguang Subject: [PATCH 06/10] ksm: identify PageKsm pages Date: Fri, 17 Jul 2009 20:30:46 +0300 Message-Id: <1247851850-4298-7-git-send-email-ieidus@redhat.com> In-Reply-To: <1247851850-4298-6-git-send-email-ieidus@redhat.com> References: <1247851850-4298-1-git-send-email-ieidus@redhat.com> <1247851850-4298-2-git-send-email-ieidus@redhat.com> <1247851850-4298-3-git-send-email-ieidus@redhat.com> <1247851850-4298-4-git-send-email-ieidus@redhat.com> <1247851850-4298-5-git-send-email-ieidus@redhat.com> <1247851850-4298-6-git-send-email-ieidus@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4127 Lines: 135 From: Hugh Dickins KSM will need to identify its kernel merged pages unambiguously, and /proc/kpageflags will probably like to do so too. Since KSM will only be substituting anonymous pages, statistics are best preserved by making a PageKsm page a special PageAnon page: one with no anon_vma. But KSM then needs its own page_add_ksm_rmap() - keep it in ksm.h near PageKsm; and do_wp_page() must COW them, unlike singly mapped PageAnons. Signed-off-by: Hugh Dickins Signed-off-by: Chris Wright Signed-off-by: Izik Eidus Cc: Wu Fengguang --- fs/proc/page.c | 5 +++++ include/linux/ksm.h | 29 +++++++++++++++++++++++++++++ mm/memory.c | 3 ++- 3 files changed, 36 insertions(+), 1 deletions(-) diff --git a/fs/proc/page.c b/fs/proc/page.c index 2707c6c..2281c2c 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -2,6 +2,7 @@ #include #include #include +#include #include #include #include @@ -95,6 +96,8 @@ static const struct file_operations proc_kpagecount_operations = { #define KPF_UNEVICTABLE 18 #define KPF_NOPAGE 20 +#define KPF_KSM 21 + /* kernel hacking assistances * WARNING: subject to change, never rely on them! */ @@ -137,6 +140,8 @@ static u64 get_uflags(struct page *page) u |= 1 << KPF_MMAP; if (PageAnon(page)) u |= 1 << KPF_ANON; + if (PageKsm(page)) + u |= 1 << KPF_KSM; /* * compound pages: export both head/tail info diff --git a/include/linux/ksm.h b/include/linux/ksm.h index eb2a448..a485c14 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -10,6 +10,7 @@ #include #include #include +#include #ifdef CONFIG_KSM int ksm_madvise(struct vm_area_struct *vma, unsigned long start, @@ -29,6 +30,27 @@ static inline void ksm_exit(struct mm_struct *mm) if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) __ksm_exit(mm); } + +/* + * A KSM page is one of those write-protected "shared pages" or "merged pages" + * which KSM maps into multiple mms, wherever identical anonymous page content + * is found in VM_MERGEABLE vmas. It's a PageAnon page, with NULL anon_vma. + */ +static inline int PageKsm(struct page *page) +{ + return ((unsigned long)page->mapping == PAGE_MAPPING_ANON); +} + +/* + * But we have to avoid the checking which page_add_anon_rmap() performs. + */ +static inline void page_add_ksm_rmap(struct page *page) +{ + if (atomic_inc_and_test(&page->_mapcount)) { + page->mapping = (void *) PAGE_MAPPING_ANON; + __inc_zone_page_state(page, NR_ANON_PAGES); + } +} #else /* !CONFIG_KSM */ static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, @@ -45,6 +67,13 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) static inline void ksm_exit(struct mm_struct *mm) { } + +static inline int PageKsm(struct page *page) +{ + return 0; +} + +/* No stub required for page_add_ksm_rmap(page) */ #endif /* !CONFIG_KSM */ #endif diff --git a/mm/memory.c b/mm/memory.c index 8b1922c..6707072 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include #include @@ -1972,7 +1973,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, * Take out anonymous pages first, anonymous shared vmas are * not dirty accountable. */ - if (PageAnon(old_page)) { + if (PageAnon(old_page) && !PageKsm(old_page)) { if (!trylock_page(old_page)) { page_cache_get(old_page); pte_unmap_unlock(page_table, ptl); -- 1.5.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/