From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 4/5] writeback: memcg dirty_throttle_control should be initialized with wb->memcg_completions Date: Tue, 29 Sep 2015 12:47:53 -0400 Message-ID: <1443545274-18787-5-git-send-email-tj@kernel.org> References: <1443545274-18787-1-git-send-email-tj@kernel.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=3R0aoVF9+puumpNz9vp7fGvtyDhyoRAMhOHoKEN0AxQ=; b=L6YN0CkphgKxWUOiTZxzNGBZnBBSJrYwAZkQYmWkvS3qo2kh+xijr2sK0zZjECXc8U UUx5yak2W/xeazlXFES7Dx8yduLQbE70VFNkDC/2S29lxKxDWcB8krbjtTL9/O4nY5DB bfd9rHrsnfm5Q0urNst5SZGpAIQ7ImgYu6FqHiB65RZ23SO8a9QKC+nSiBlMQBXcgbfF cfHz1JMoxqpvZNE+GWzsdhKfzdRtXETnrSEuLBQbQSkKx12gEspy2OvaD6bKI+nH297C SeCbIJWbTLwMjwicudmJNhAhWp3DGR1KfqZ43HaEDPH5W9VevY5zPsz8n9FbH6NoFRki uUtQ== In-Reply-To: <1443545274-18787-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tytso-3s7WtUTddSA@public.gmane.org, dedekind1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, decui-0li6OtcxBFHby3iVrkZq2A@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org, Tejun Heo MDTC_INIT() is used to initialize dirty_throttle_control for memcg domains. It used DTC_INIT_COMMON() to initialized mdtc->wb and ->wb_completions which is incorrect as DTC_INIT_COMMON() sets the latter to wb->completions instead of wb->memcg_completions. This can lead to wildly incorrect results when calculating the proportion of dirty memory the memcg domain should get. Remove DTC_INIT_COMMON() and update MDTC_INIT() to initialize mdtc->wb_completions to wb->memcg_completions. Signed-off-by: Tejun Heo Fixes: c2aa723a6093 ("writeback: implement memcg writeback domain based throttling") --- mm/page-writeback.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 0f1a94e..56c0bff 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -145,9 +145,6 @@ struct dirty_throttle_control { unsigned long pos_ratio; }; -#define DTC_INIT_COMMON(__wb) .wb = (__wb), \ - .wb_completions = &(__wb)->completions - /* * Length of period for aging writeout fractions of bdis. This is an * arbitrarily chosen number. The longer the period, the slower fractions will @@ -157,12 +154,16 @@ struct dirty_throttle_control { #ifdef CONFIG_CGROUP_WRITEBACK -#define GDTC_INIT(__wb) .dom = &global_wb_domain, \ - DTC_INIT_COMMON(__wb) +#define GDTC_INIT(__wb) .wb = (__wb), \ + .dom = &global_wb_domain, \ + .wb_completions = &(__wb)->completions + #define GDTC_INIT_NO_WB .dom = &global_wb_domain -#define MDTC_INIT(__wb, __gdtc) .dom = mem_cgroup_wb_domain(__wb), \ - .gdtc = __gdtc, \ - DTC_INIT_COMMON(__wb) + +#define MDTC_INIT(__wb, __gdtc) .wb = (__wb), \ + .dom = mem_cgroup_wb_domain(__wb), \ + .wb_completions = &(__wb)->memcg_completions, \ + .gdtc = __gdtc static bool mdtc_valid(struct dirty_throttle_control *dtc) { @@ -213,7 +214,8 @@ static void wb_min_max_ratio(struct bdi_writeback *wb, #else /* CONFIG_CGROUP_WRITEBACK */ -#define GDTC_INIT(__wb) DTC_INIT_COMMON(__wb) +#define GDTC_INIT(__wb) .wb = (__wb), \ + .wb_completions = &(__wb)->completions #define GDTC_INIT_NO_WB #define MDTC_INIT(__wb, __gdtc) -- 2.4.3