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>
diff --git a/mm/memory.c b/mm/memory.c
index c0e7741..f82b359b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1639,6 +1639,7 @@
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 @@
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 @@
* 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 @@
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 @@
anon = 1; /* no anon but release vmf.page */
goto out;
}
+ page_mkwrite = 1;
}
}
@@ -2453,7 +2458,7 @@
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);
}