From: Tejun Heo <tj@kernel.org>
To: Dennis Zhou <dennisszhou@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>,
Johannes Weiner <hannes@cmpxchg.org>,
Josef Bacik <josef@toxicpanda.com>,
kernel-team@fb.com, linux-block@vger.kernel.org,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 13/15] blkcg: change blkg reference counting to use percpu_ref
Date: Fri, 31 Aug 2018 17:31:59 -0700 [thread overview]
Message-ID: <20180901003159.GK1488037@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20180831015356.69796-14-dennisszhou@gmail.com>
Hello,
On Thu, Aug 30, 2018 at 09:53:54PM -0400, Dennis Zhou wrote:
> @@ -217,6 +240,10 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
> blkg_get(blkg->parent);
> }
>
> + ret = percpu_ref_init(&blkg->refcnt, __blkg_release, 0, GFP_KERNEL);
So, while this would work in some configs, you can't depend on RCU
grace period inside percpu_ref. blkg is now percpu-reference counted
and rcu protected object - it has to explicitly go through a rcu grace
period before release.
Thanks.
--
tejun
next prev parent reply other threads:[~2018-09-01 0:32 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-31 1:53 [PATCH 00/15] blkcg ref count refactor/cleanup + blkcg avg_lat Dennis Zhou
2018-08-31 1:53 ` [PATCH 01/15] Revert "blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()" Dennis Zhou
2018-08-31 1:53 ` [PATCH 02/15] blkcg: delay blkg destruction until after writeback has finished Dennis Zhou
2018-08-31 15:27 ` Josef Bacik
2018-08-31 20:19 ` Dennis Zhou
2018-08-31 1:53 ` [PATCH 03/15] blkcg: use tryget logic when associating a blkg with a bio Dennis Zhou
2018-08-31 15:30 ` Josef Bacik
2018-08-31 20:20 ` Dennis Zhou
2018-08-31 1:53 ` [PATCH 04/15] blkcg: fix ref count issue with bio_blkcg using task_css Dennis Zhou
2018-08-31 15:35 ` Josef Bacik
2018-08-31 23:04 ` Tejun Heo
2018-09-06 15:21 ` Dennis Zhou
2018-08-31 1:53 ` [PATCH 05/15] blkcg: update blkg_lookup_create to do locking Dennis Zhou
2018-08-31 15:37 ` Josef Bacik
2018-08-31 23:09 ` Tejun Heo
2018-08-31 1:53 ` [PATCH 06/15] blkcg: always associate a bio with a blkg Dennis Zhou
2018-08-31 9:01 ` kbuild test robot
2018-08-31 10:02 ` kbuild test robot
2018-08-31 23:16 ` Tejun Heo
2018-09-06 20:41 ` Dennis Zhou
2018-09-07 3:03 ` [LKP] [blkcg] c02c58dab2: WARNING:at_block/blk-throttle.c:#blk_throtl_bio kernel test robot
2018-08-31 1:53 ` [PATCH 07/15] blkcg: consolidate bio_issue_init and blkg association Dennis Zhou
2018-08-31 9:19 ` kbuild test robot
2018-08-31 11:11 ` kbuild test robot
2018-08-31 15:42 ` Josef Bacik
2018-09-06 20:43 ` Dennis Zhou
2018-08-31 23:45 ` Tejun Heo
2018-08-31 1:53 ` [PATCH 08/15] blkcg: associate a blkg for pages being evicted by swap Dennis Zhou
2018-08-31 15:44 ` Josef Bacik
2018-08-31 23:47 ` Tejun Heo
2018-08-31 1:53 ` [PATCH 09/15] blkcg: associate writeback bios with a blkg Dennis Zhou
2018-08-31 15:45 ` Josef Bacik
2018-08-31 23:53 ` Tejun Heo
2018-08-31 1:53 ` [PATCH 10/15] blkcg: remove bio->bi_css and instead use bio->bi_blkg Dennis Zhou
2018-08-31 15:46 ` Josef Bacik
2018-09-01 0:13 ` Tejun Heo
2018-08-31 1:53 ` [PATCH 11/15] blkcg: remove additional reference to the css Dennis Zhou
2018-09-01 0:26 ` Tejun Heo
2018-09-06 20:45 ` Dennis Zhou
2018-08-31 1:53 ` [PATCH 12/15] blkcg: cleanup and make blk_get_rl use blkg_lookup_create Dennis Zhou
2018-09-01 0:29 ` Tejun Heo
2018-09-11 2:37 ` [LKP] [blkcg] 22f657e287: general_protection_fault:#[##] kernel test robot
2018-08-31 1:53 ` [PATCH 13/15] blkcg: change blkg reference counting to use percpu_ref Dennis Zhou
2018-08-31 15:49 ` Josef Bacik
2018-09-01 0:31 ` Tejun Heo [this message]
2018-09-06 20:46 ` Dennis Zhou
2018-09-07 3:08 ` [LKP] [blkcg] 6ef69a3a0b: WARNING:suspicious_RCU_usage kernel test robot
2018-08-31 1:53 ` [PATCH 14/15] blkcg: rename blkg_try_get to blkg_tryget Dennis Zhou
2018-08-31 15:50 ` Josef Bacik
2018-09-01 0:32 ` Tejun Heo
2018-08-31 1:53 ` [PATCH 15/15] blkcg: add average latency tracking to blk-cgroup Dennis Zhou
2018-08-31 10:22 ` kbuild test robot
2018-08-31 11:38 ` kbuild test robot
2018-09-01 0:35 ` [PATCH 00/15] blkcg ref count refactor/cleanup + blkcg avg_lat Tejun Heo
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