From 3a6927906f1b2adf5a31b789322d32eb8559ada0 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@woody.linux-foundation.org>
Date: Wed, 19 Dec 2007 14:05:13 -0800
Subject: [PATCH] Do dirty page accounting when removing a page from the page
cache
Krzysztof Oledzki noticed a dirty page accounting leak on some of his
machines, causing the machine to eventually lock up when the kernel
decided that there was too much dirty data, but nobody could actually
write anything out to fix it.
The culprit turns out to be filesystems (cough ext3 with data=journal
cough) that re-dirty the page when the "->invalidatepage()" callback is
called.
Fix it up by doing a final dirty page accounting check when we actually
remove the page from the page cache.
This fixes bugzilla entry 9182:
http://bugzilla.kernel.org/show_bug.cgi?id=9182
Tested-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Krzysztof Oledzki <olel@ans.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/filemap.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/mm/filemap.c b/mm/filemap.c
index 188cf5fd3e8d4a..f4d0cded0e10aa 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -124,6 +124,18 @@ void __remove_from_page_cache(struct page *page)
mapping->nrpages--;
__dec_zone_page_state(page, NR_FILE_PAGES);
BUG_ON(page_mapped(page));
+
+ /*
+ * Some filesystems seem to re-dirty the page even after
+ * the VM has canceled the dirty bit (eg ext3 journaling).
+ *
+ * Fix it up by doing a final dirty accounting check after
+ * having removed the page entirely.
+ */
+ if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
+ dec_zone_page_state(page, NR_FILE_DIRTY);
+ dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
+ }
}
void remove_from_page_cache(struct page *page)
--
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