lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [day] [month] [year] [list]
Message-ID: <45C9A43F.2010401@hitachi.com>
Date:	Wed, 07 Feb 2007 19:04:47 +0900
From:	Tomoki Sekiyama <tomoki.sekiyama.qu@...achi.com>
To:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Cc:	yumiko.sugita.yf@...achi.com, masami.hiramatsu.pt@...achi.com,
	yuji.kakutani.uw@...achi.com, hidehiro.kawai.ez@...achi.com,
	satoshi.oshima.fk@...achi.com
Subject: [BUG][PATCH] mm: Fix dirty page accounting per backing_dev

Hello Andrew,

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@...achi.com>
---
 mm/truncate.c |    1 +
 1 file changed, 1 insertion(+)

Index: linux-2.6.20-rc6-mm3/mm/truncate.c
===================================================================
--- linux-2.6.20-rc6-mm3.orig/mm/truncate.c
+++ linux-2.6.20-rc6-mm3/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);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ