The patch titled
mm: Fix dirty page accounting per backing_dev
has been added to the -mm tree. Its filename is
per-backing_dev-dirty-and-writeback-page-accounting-fix.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: mm: Fix dirty page accounting per backing_dev
From: Tomoki Sekiyama <tomoki.sekiyama.qu@xxxxxxxxxxx>
I found a suspicious bug of I/O accounting in 2.6.20-rc6-mm3. The number
of dirty pages per backing_dev available from
/sys/block/<dev>/queue/nr_dirty keeps growing when a file is rapidly
overwritten several times.
For example:
% cat /sys/block/sda/queue/nr_dirty
104
% for i in 1 2; do dd if=/dev/zero of=dummy bs=4096 count=1; done; sync
% cat /sys/block/sda/queue/nr_dirty
105
% for i in 1 2 3; do dd if=/dev/zero of=dummy bs=4096 count=1; done; sync
% cat /sys/block/sda/queue/nr_dirty
107
This patch fixes it.
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/truncate.c | 1 +
1 files changed, 1 insertion(+)
diff -puN mm/truncate.c~per-backing_dev-dirty-and-writeback-page-accounting-fix mm/truncate.c
--- a/mm/truncate.c~per-backing_dev-dirty-and-writeback-page-accounting-fix
+++ a/mm/truncate.c
@@ -70,6 +70,7 @@ void cancel_dirty_page(struct page *page
if (TestClearPageDirty(page)) {
struct address_space *mapping = page->mapping;
if (mapping && mapping_cap_account_dirty(mapping)) {
+ atomic_long_dec(&mapping->backing_dev_info->nr_dirty);
dec_zone_page_state(page, NR_FILE_DIRTY);
if (account_size)
task_io_account_cancelled_write(account_size);
_
Patches currently in -mm which might be from tomoki.sekiyama.qu@xxxxxxxxxxx are
per-backing_dev-dirty-and-writeback-page-accounting-fix.patch
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