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From: Tejun Heo <tj@kernel.org>
To: Josef Bacik <josef@toxicpanda.com>
Cc: axboe@kernel.dk, kernel-team@fb.com, linux-block@vger.kernel.org,
	akpm@linux-foundation.org, linux-mm@kvack.org,
	hannes@cmpxchg.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 05/13] swap,blkcg: issue swap io with the appropriate context
Date: Wed, 30 May 2018 09:05:27 -0700	[thread overview]
Message-ID: <20180530160527.GM1351649@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20180529211724.4531-6-josef@toxicpanda.com>

On Tue, May 29, 2018 at 05:17:16PM -0400, Josef Bacik wrote:
> From: Tejun Heo <tj@kernel.org>
> 
> For backcharging we need to know who the page belongs to when swapping
> it out.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Josef Bacik <jbacik@fb.com>
> ---
>  mm/page_io.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/mm/page_io.c b/mm/page_io.c
> index a552cb37e220..61e1268e5dbc 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -339,6 +339,16 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
>  		goto out;
>  	}
>  	bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
> +#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
> +	if (page->mem_cgroup) {
> +		struct cgroup_subsys_state *blkcg_css;
> +
> +		blkcg_css = cgroup_get_e_css(page->mem_cgroup->css.cgroup,
> +					     &io_cgrp_subsys);
> +		bio_associate_blkcg(bio, blkcg_css);
> +		css_put(blkcg_css);
> +	}
> +#endif

So, this ignores the cases where bdev_write_page() is the one which
does the writes.  If my reading is correct, only brd, zram, btt and
pmem implement bdev_ops->rw_page() and take bdev_write_page() path, so
it shouldn't be a problem in majority of cases.

I don't think we need to address ->rw_page() case right now but it
might be a good idea to add a comment explaining the ommission.

Thanks.

-- 
tejun

  parent reply	other threads:[~2018-05-30 16:05 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-29 21:17 [PATCH 00/13] Introdue io.latency io controller for cgroups Josef Bacik
2018-05-29 21:17 ` [PATCH 01/13] block: add bi_blkg to the bio " Josef Bacik
2018-05-30 15:49   ` Tejun Heo
2018-05-29 21:17 ` [PATCH 02/13] block: introduce bio_issue_as_root_blkg Josef Bacik
2018-05-30 15:53   ` Tejun Heo
2018-05-29 21:17 ` [PATCH 03/13] blk-cgroup: allow controllers to output their own stats Josef Bacik
2018-05-30 15:54   ` Tejun Heo
2018-05-29 21:17 ` [PATCH 04/13] blk: introduce REQ_SWAP Josef Bacik
2018-05-30 15:58   ` Tejun Heo
2018-05-29 21:17 ` [PATCH 05/13] swap,blkcg: issue swap io with the appropriate context Josef Bacik
2018-05-30 13:06   ` Johannes Weiner
2018-05-30 16:05   ` Tejun Heo [this message]
2018-05-29 21:17 ` [PATCH 06/13] blkcg: add generic throttling mechanism Josef Bacik
2018-05-30 13:11   ` Johannes Weiner
2018-05-30 16:26   ` Tejun Heo
2018-05-29 21:17 ` [PATCH 07/13] memcontrol: schedule throttling if we are congested Josef Bacik
2018-05-30 14:15   ` Johannes Weiner
2018-05-29 21:17 ` [PATCH 08/13] blk-stat: export helpers for modifying blk_rq_stat Josef Bacik
2018-05-30 16:31   ` Tejun Heo
2018-05-29 21:17 ` [PATCH 09/13] blk-rq-qos: refactor out common elements of blk-wbt Josef Bacik
2018-05-29 21:17 ` [PATCH 10/13] block: remove external dependency on wbt_flags Josef Bacik
2018-05-29 21:17 ` [PATCH 11/13] rq-qos: introduce dio_bio callback Josef Bacik
2018-05-29 21:17 ` [PATCH 12/13] block: introduce blk-iolatency io controller Josef Bacik
2018-05-29 22:07   ` Randy Dunlap
2018-05-30 16:40   ` Tejun Heo
2018-05-29 21:17 ` [PATCH 13/13] Documentation: add a doc for blk-iolatency Josef Bacik
2018-05-30 16:44   ` Tejun Heo
2018-05-30 18:32   ` Randy Dunlap
2018-06-05 13:29 [PATCH 00/13][V2] Introduce io.latency io controller for cgroups Josef Bacik
2018-06-05 13:29 ` [PATCH 05/13] swap,blkcg: issue swap io with the appropriate context Josef Bacik
2018-06-05 19:41   ` Tejun Heo
2018-06-11 14:06   ` Johannes Weiner

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