lkml.org 
[lkml]   [2009]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 05/10] ksm: no debug in page_dup_rmap()
Date
From: Hugh Dickins <hugh.dickins@tiscali.co.uk>

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@tiscali.co.uk>
Signed-off-by: Chris Wright <chrisw@redhat.com>
Signed-off-by: Izik Eidus <ieidus@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
---
include/linux/rmap.h | 6 +-----
mm/memory.c | 2 +-
mm/rmap.c | 21 ---------------------
3 files changed, 2 insertions(+), 27 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index bf116d0..477841d 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -71,14 +71,10 @@ void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned lon
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 --git a/mm/memory.c b/mm/memory.c
index 8159a62..8b1922c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -595,7 +595,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
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 --git a/mm/rmap.c b/mm/rmap.c
index 836c6c6..ab84e45 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -709,27 +709,6 @@ void page_add_file_rmap(struct page *page)
}
}

-#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
--
1.5.6.5


\
 
 \ /
  Last update: 2009-07-17 19:33    [W:0.172 / U:5.012 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site