The patch titled
ksm: no debug in page_dup_rmap()
has been added to the -mm tree. Its filename is
ksm-no-debug-in-page_dup_rmap.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: no debug in page_dup_rmap()
From: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
page_dup_rmap(), used on each mapped page when forking, was originally
just an inline atomic_inc of mapcount. 2.6.22 added CONFIG_DEBUG_VM
out-of-line checks to it, which would need to be ever-so-slightly
complicated to allow for the PageKsm() we're about to define.
But I think these checks never caught anything. And if it's coding errors
we're worried about, such checks should be in page_remove_rmap() too, not
just when forking; whereas if it's pagetable corruption we're worried
about, then they shouldn't be limited to CONFIG_DEBUG_VM.
Oh, just revert page_dup_rmap() to an inline atomic_inc of mapcount.
Signed-off-by: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxx>
Signed-off-by: Izik Eidus <ieidus@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/rmap.h | 6 +-----
mm/memory.c | 2 +-
mm/rmap.c | 21 ---------------------
3 files changed, 2 insertions(+), 27 deletions(-)
diff -puN include/linux/rmap.h~ksm-no-debug-in-page_dup_rmap include/linux/rmap.h
--- a/include/linux/rmap.h~ksm-no-debug-in-page_dup_rmap
+++ a/include/linux/rmap.h
@@ -71,14 +71,10 @@ void page_add_new_anon_rmap(struct page
void page_add_file_rmap(struct page *);
void page_remove_rmap(struct page *);
-#ifdef CONFIG_DEBUG_VM
-void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address);
-#else
-static inline void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
+static inline void page_dup_rmap(struct page *page)
{
atomic_inc(&page->_mapcount);
}
-#endif
/*
* Called from mm/vmscan.c to handle paging out
diff -puN mm/memory.c~ksm-no-debug-in-page_dup_rmap mm/memory.c
--- a/mm/memory.c~ksm-no-debug-in-page_dup_rmap
+++ a/mm/memory.c
@@ -595,7 +595,7 @@ copy_one_pte(struct mm_struct *dst_mm, s
page = vm_normal_page(vma, addr, pte);
if (page) {
get_page(page);
- page_dup_rmap(page, vma, addr);
+ page_dup_rmap(page);
rss[!!PageAnon(page)]++;
}
diff -puN mm/rmap.c~ksm-no-debug-in-page_dup_rmap mm/rmap.c
--- a/mm/rmap.c~ksm-no-debug-in-page_dup_rmap
+++ a/mm/rmap.c
@@ -709,27 +709,6 @@ void page_add_file_rmap(struct page *pag
}
}
-#ifdef CONFIG_DEBUG_VM
-/**
- * page_dup_rmap - duplicate pte mapping to a page
- * @page: the page to add the mapping to
- * @vma: the vm area being duplicated
- * @address: the user virtual address mapped
- *
- * For copy_page_range only: minimal extract from page_add_file_rmap /
- * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's
- * quicker.
- *
- * The caller needs to hold the pte lock.
- */
-void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
-{
- if (PageAnon(page))
- __page_check_anon_rmap(page, vma, address);
- atomic_inc(&page->_mapcount);
-}
-#endif
-
/**
* page_remove_rmap - take down pte mapping from a page
* @page: page to remove mapping from
_
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
