The patch titled ksm: identify PageKsm pages has been added to the -mm tree. Its filename is ksm-identify-pageksm-pages.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: ksm: identify PageKsm pages From: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx> 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 <hugh.dickins@xxxxxxxxxxxxx> Signed-off-by: Chris Wright <chrisw@xxxxxxxxxx> Signed-off-by: Izik Eidus <ieidus@xxxxxxxxxx> Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx> Cc: Balbir Singh <balbir@xxxxxxxxxx> Cc: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Lee Schermerhorn <lee.schermerhorn@xxxxxx> Cc: Avi Kivity <avi@xxxxxxxxxx> Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/page.c | 5 +++++ include/linux/ksm.h | 29 +++++++++++++++++++++++++++++ mm/memory.c | 3 ++- 3 files changed, 36 insertions(+), 1 deletion(-) diff -puN fs/proc/page.c~ksm-identify-pageksm-pages fs/proc/page.c --- a/fs/proc/page.c~ksm-identify-pageksm-pages +++ a/fs/proc/page.c @@ -2,6 +2,7 @@ #include <linux/compiler.h> #include <linux/fs.h> #include <linux/init.h> +#include <linux/ksm.h> #include <linux/mm.h> #include <linux/mmzone.h> #include <linux/proc_fs.h> @@ -95,6 +96,8 @@ static const struct file_operations proc #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 -puN include/linux/ksm.h~ksm-identify-pageksm-pages include/linux/ksm.h --- a/include/linux/ksm.h~ksm-identify-pageksm-pages +++ a/include/linux/ksm.h @@ -10,6 +10,7 @@ #include <linux/bitops.h> #include <linux/mm.h> #include <linux/sched.h> +#include <linux/vmstat.h> #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_st 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_str 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 -puN mm/memory.c~ksm-identify-pageksm-pages mm/memory.c --- a/mm/memory.c~ksm-identify-pageksm-pages +++ a/mm/memory.c @@ -45,6 +45,7 @@ #include <linux/swap.h> #include <linux/highmem.h> #include <linux/pagemap.h> +#include <linux/ksm.h> #include <linux/rmap.h> #include <linux/module.h> #include <linux/delayacct.h> @@ -1972,7 +1973,7 @@ static int do_wp_page(struct mm_struct * * 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); _ Patches currently in -mm which might be from hugh.dickins@xxxxxxxxxxxxx are mm-avoid-endless-looping-for-oom-killed-tasks.patch mm-oom-analysis-add-shmem-vmstat.patch ksm-add-mmu_notifier-set_pte_at_notify.patch ksm-first-tidy-up-madvise_vma.patch ksm-define-madv_mergeable-and-madv_unmergeable.patch ksm-the-mm-interface-to-ksm.patch ksm-no-debug-in-page_dup_rmap.patch ksm-identify-pageksm-pages.patch ksm-kernel-samepage-merging.patch ksm-prevent-mremap-move-poisoning.patch ksm-change-copyright-message.patch ksm-change-ksm-nice-level-to-be-5.patch getrusage-fill-ru_maxrss-value.patch getrusage-fill-ru_maxrss-value-update.patch ramfs-move-ramfs_magic-to-include-linux-magich.patch prio_tree-debugging-patch.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html