From a200ee182a016752464a12cb2e8762e48254bb09 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 8 Oct 2007 18:54:37 +0200
Subject: [PATCH] mm: set_page_dirty_balance() vs ->page_mkwrite()
All the current page_mkwrite() implementations also set the page dirty. Which
results in the set_page_dirty_balance() call to _not_ call balance, because the
page is already found dirty.
This allows us to dirty a _lot_ of pages without ever hitting
balance_dirty_pages(). Not good (tm).
Force a balance call if ->page_mkwrite() was successful.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/writeback.h | 2 +-
mm/memory.c | 9 +++++++--
mm/page-writeback.c | 4 ++--
3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 4ef4d22e5e43..b4af6bcb7b7a 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -127,7 +127,7 @@ int sync_page_range(struct inode *inode, struct address_space *mapping,
loff_t pos, loff_t count);
int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
loff_t pos, loff_t count);
-void set_page_dirty_balance(struct page *page);
+void set_page_dirty_balance(struct page *page, int page_mkwrite);
void writeback_set_ratelimit(void);
/* pdflush.c */
diff --git a/mm/memory.c b/mm/memory.c
index c0e7741a98de..f82b359b2745 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1639,6 +1639,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page *old_page, *new_page;
pte_t entry;
int reuse = 0, ret = 0;
+ int page_mkwrite = 0;
struct page *dirty_page = NULL;
old_page = vm_normal_page(vma, address, orig_pte);
@@ -1687,6 +1688,8 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
page_cache_release(old_page);
if (!pte_same(*page_table, orig_pte))
goto unlock;
+
+ page_mkwrite = 1;
}
dirty_page = old_page;
get_page(dirty_page);
@@ -1774,7 +1777,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
* do_no_page is protected similarly.
*/
wait_on_page_locked(dirty_page);
- set_page_dirty_balance(dirty_page);
+ set_page_dirty_balance(dirty_page, page_mkwrite);
put_page(dirty_page);
}
return ret;
@@ -2322,6 +2325,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
struct page *dirty_page = NULL;
struct vm_fault vmf;
int ret;
+ int page_mkwrite = 0;
vmf.virtual_address = (void __user *)(address & PAGE_MASK);
vmf.pgoff = pgoff;
@@ -2398,6 +2402,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
anon = 1; /* no anon but release vmf.page */
goto out;
}
+ page_mkwrite = 1;
}
}
@@ -2453,7 +2458,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (anon)
page_cache_release(vmf.page);
else if (dirty_page) {
- set_page_dirty_balance(dirty_page);
+ set_page_dirty_balance(dirty_page, page_mkwrite);
put_page(dirty_page);
}
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 63512a9ed57e..44720363374c 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -274,9 +274,9 @@ static void balance_dirty_pages(struct address_space *mapping)
pdflush_operation(background_writeout, 0);
}
-void set_page_dirty_balance(struct page *page)
+void set_page_dirty_balance(struct page *page, int page_mkwrite)
{
- if (set_page_dirty(page)) {
+ if (set_page_dirty(page) || page_mkwrite) {
struct address_space *mapping = page_mapping(page);
if (mapping)
--
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