From: Johannes Weiner <jweiner@redhat.com>
To: Sonny Rao <sonnyrao@chromium.org>
Cc: linux-kernel@vger.kernel.org,
Fengguang Wu <fengguang.wu@intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.cz>,
linux-mm@kvack.org, Mandeep Singh Baines <msb@chromium.org>,
Olof Johansson <olofj@chromium.org>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
Aaron Durbin <adurbin@chromium.org>,
Puneet Kumar <puneetster@chromium.org>
Subject: Re: [PATCH] mm: Fix calculation of dirtyable memory
Date: Mon, 12 Nov 2012 15:32:21 -0500 [thread overview]
Message-ID: <20121112203221.GB4511@redhat.com> (raw)
In-Reply-To: <1352748928-738-1-git-send-email-sonnyrao@chromium.org>
On Mon, Nov 12, 2012 at 11:35:28AM -0800, Sonny Rao wrote:
> The system uses global_dirtyable_memory() to calculate
> number of dirtyable pages/pages that can be allocated
> to the page cache. A bug causes an underflow thus making
> the page count look like a big unsigned number. This in turn
> confuses the dirty writeback throttling to aggressively write
> back pages as they become dirty (usually 1 page at a time).
>
> Fix is to ensure there is no underflow while doing the math.
>
> Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
> Signed-off-by: Puneet Kumar <puneetster@chromium.org>
Thanks for debugging and sending in the patch.
It might be useful to note in the changelog that the crawling
writeback problem only affects highmem systems because of the way the
underflowed count of high memory is subtracted from the overall amount
of dirtyable memory.
And that the problem was introduced with v3.2-4896-gab8fabd (which
means that we should include Cc: stable@kernel.org for 3.3+).
The diff itself looks good to me, thanks again:
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-11-12 20:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-08 23:25 [PATCH] mm: Fix calculation of dirtyable memory Sonny Rao
2012-11-08 23:37 ` Andrew Morton
2012-11-09 0:42 ` [PATCHv2] " Sonny Rao
2012-11-09 0:45 ` Sonny Rao
2012-11-09 0:52 ` Sonny Rao
2012-11-09 2:36 ` Fengguang Wu
2012-11-12 19:35 ` [PATCH] " Sonny Rao
2012-11-12 20:32 ` Johannes Weiner [this message]
2012-11-12 21:35 ` [PATCHv4] " Sonny Rao
2012-11-17 20:41 ` Damien Wyart
2012-11-19 13:40 ` Johannes Weiner
2012-11-19 18:41 ` [PATCHv5] " Sonny Rao
2012-11-19 18:44 ` Sonny Rao
2012-11-19 19:22 ` Damien Wyart
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121112203221.GB4511@redhat.com \
--to=jweiner@redhat.com \
--cc=a.p.zijlstra@chello.nl \
--cc=adurbin@chromium.org \
--cc=akpm@linux-foundation.org \
--cc=fengguang.wu@intel.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.cz \
--cc=msb@chromium.org \
--cc=olofj@chromium.org \
--cc=puneetster@chromium.org \
--cc=sonnyrao@chromium.org \
--cc=wad@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).