From 8ac9e802007e99534ec66af850ef7b099df27499 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Wed, 30 Dec 2009 23:00:30 +0000 Subject: [PATCH] ksm: fix mlockfreed to munlocked 2.6.33-rc1 commit 73848b4684e84a84cfd1555af78d41158f31e16b, adjusted to include 31e855ea7173bdb0520f9684580423a9560f66e0's movement of the unlock_page(oldpage), but omit other intervening cleanups. When KSM merges an mlocked page, it has been forgetting to munlock it: that's been left to free_page_mlock(), which reports it in /proc/vmstat as unevictable_pgs_mlockfreed instead of unevictable_pgs_munlocked, which indicates that such pages _might_ be left unevictable for long after they should be evictable. Call munlock_vma_page() to fix that. Signed-off-by: Hugh Dickins Signed-off-by: Greg Kroah-Hartman --- mm/internal.h | 3 ++- mm/ksm.c | 14 +++++++------- mm/mlock.c | 4 ++-- 3 files changed, 11 insertions(+), 10 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 22ec8d2b0fb8..17bc0df273bb 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -107,9 +107,10 @@ static inline int is_mlocked_vma(struct vm_area_struct *vma, struct page *page) } /* - * must be called with vma's mmap_sem held for read, and page locked. + * must be called with vma's mmap_sem held for read or write, and page locked. */ extern void mlock_vma_page(struct page *page); +extern void munlock_vma_page(struct page *page); /* * Clear the page's PageMlocked(). This can be useful in a situation where diff --git a/mm/ksm.c b/mm/ksm.c index 5575f8628fef..e9501f833374 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -34,6 +34,7 @@ #include #include +#include "internal.h" /* * A few notes about the KSM scanning process, @@ -767,15 +768,14 @@ static int try_to_merge_one_page(struct vm_area_struct *vma, * ptes are necessarily already write-protected. But in either * case, we need to lock and check page_count is not raised. */ - if (write_protect_page(vma, oldpage, &orig_pte)) { - unlock_page(oldpage); - goto out_putpage; - } - unlock_page(oldpage); - - if (pages_identical(oldpage, newpage)) + if (write_protect_page(vma, oldpage, &orig_pte) == 0 && + pages_identical(oldpage, newpage)) err = replace_page(vma, oldpage, newpage, orig_pte); + if ((vma->vm_flags & VM_LOCKED) && !err) + munlock_vma_page(oldpage); + + unlock_page(oldpage); out_putpage: put_page(oldpage); put_page(newpage); diff --git a/mm/mlock.c b/mm/mlock.c index bd6f0e466f6c..2e05c97b04f5 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -99,14 +99,14 @@ void mlock_vma_page(struct page *page) * not get another chance to clear PageMlocked. If we successfully * isolate the page and try_to_munlock() detects other VM_LOCKED vmas * mapping the page, it will restore the PageMlocked state, unless the page - * is mapped in a non-linear vma. So, we go ahead and SetPageMlocked(), + * is mapped in a non-linear vma. So, we go ahead and ClearPageMlocked(), * perhaps redundantly. * If we lose the isolation race, and the page is mapped by other VM_LOCKED * vmas, we'll detect this in vmscan--via try_to_munlock() or try_to_unmap() * either of which will restore the PageMlocked state by calling * mlock_vma_page() above, if it can grab the vma's mmap sem. */ -static void munlock_vma_page(struct page *page) +void munlock_vma_page(struct page *page) { BUG_ON(!PageLocked(page)); -- 2.34.1