From: Prateek Sood <prsood@codeaurora.org> To: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org>, avagin@gmail.com, mingo@kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, sramana@codeaurora.org Subject: Re: [PATCH] cgroup/cpuset: fix circular locking dependency Date: Sat, 16 Dec 2017 00:34:18 +0530 [thread overview] Message-ID: <7c25aac5-ef23-26c6-5096-4f1ab1b53b70@codeaurora.org> (raw) In-Reply-To: <20171213160617.GQ3919388@devbig577.frc2.facebook.com> On 12/13/2017 09:36 PM, Tejun Heo wrote: > Hello, Prateek. > > On Wed, Dec 13, 2017 at 01:20:46PM +0530, Prateek Sood wrote: >> This change makes the usage of cpuset_hotplug_workfn() from cpu >> hotplug path synchronous. For memory hotplug it still remains >> asynchronous. > > Ah, right. > >> Memory migration happening from cpuset_hotplug_workfn() is >> already asynchronous by queuing cpuset_migrate_mm_workfn() in >> cpuset_migrate_mm_wq. >> >> cpuset_hotplug_workfn() >> cpuset_hotplug_workfn(() >> cpuset_migrate_mm() >> queue_work(cpuset_migrate_mm_wq) >> >> It seems that memory migration latency might not have >> impact with this change. >> >> Please let me know if you meant something else by cpuset >> migration taking time when memory migration is turned on. > > No, I didn't. I was just confused about which part became > synchronous. So, I don't have anything against making the cpu part > synchronous, but let's not do that as the fix to the deadlocks cuz, > while we can avoid them by changing cpuset, I don't think cpuset is > the root cause for them. If there are benefits to making cpuset cpu > migration synchronous, let's do that for those benefits. Making CPU part synchronous can only be achieved if we retain the patch for inverting the locking order for cpuset_mutex and cpu_hotplug_lock. > > Thanks. > Peter, Do you suggest taking both the patches: 1) Inverting locking order of cpuset_mutex and cpu_hotplug_lock. 2) Make cpuset hotplug work synchronous. or https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git/commit/?h=for-4.15-fixes&id=e8b3f8db7aad99fcc5234fc5b89984ff6620de3d I would leave it for you and TJ to decide on this. Thanks -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: Prateek Sood <prsood-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, avagin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sramana-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org Subject: Re: [PATCH] cgroup/cpuset: fix circular locking dependency Date: Sat, 16 Dec 2017 00:34:18 +0530 [thread overview] Message-ID: <7c25aac5-ef23-26c6-5096-4f1ab1b53b70@codeaurora.org> (raw) In-Reply-To: <20171213160617.GQ3919388-4dN5La/x3IkLX0oZNxdnEQ2O0Ztt9esIQQ4Iyu8u01E@public.gmane.org> On 12/13/2017 09:36 PM, Tejun Heo wrote: > Hello, Prateek. > > On Wed, Dec 13, 2017 at 01:20:46PM +0530, Prateek Sood wrote: >> This change makes the usage of cpuset_hotplug_workfn() from cpu >> hotplug path synchronous. For memory hotplug it still remains >> asynchronous. > > Ah, right. > >> Memory migration happening from cpuset_hotplug_workfn() is >> already asynchronous by queuing cpuset_migrate_mm_workfn() in >> cpuset_migrate_mm_wq. >> >> cpuset_hotplug_workfn() >> cpuset_hotplug_workfn(() >> cpuset_migrate_mm() >> queue_work(cpuset_migrate_mm_wq) >> >> It seems that memory migration latency might not have >> impact with this change. >> >> Please let me know if you meant something else by cpuset >> migration taking time when memory migration is turned on. > > No, I didn't. I was just confused about which part became > synchronous. So, I don't have anything against making the cpu part > synchronous, but let's not do that as the fix to the deadlocks cuz, > while we can avoid them by changing cpuset, I don't think cpuset is > the root cause for them. If there are benefits to making cpuset cpu > migration synchronous, let's do that for those benefits. Making CPU part synchronous can only be achieved if we retain the patch for inverting the locking order for cpuset_mutex and cpu_hotplug_lock. > > Thanks. > Peter, Do you suggest taking both the patches: 1) Inverting locking order of cpuset_mutex and cpu_hotplug_lock. 2) Make cpuset hotplug work synchronous. or https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git/commit/?h=for-4.15-fixes&id=e8b3f8db7aad99fcc5234fc5b89984ff6620de3d I would leave it for you and TJ to decide on this. Thanks -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2017-12-15 19:04 UTC|newest] Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-11-28 1:22 cgroup/for-next: WARNING: possible circular locking dependency detected in cpuset_write_resmask Andrei Vagin 2017-11-28 11:35 ` [PATCH] cgroup/cpuset: fix circular locking dependency Prateek Sood 2017-12-04 5:14 ` Prateek Sood 2017-12-04 5:14 ` Prateek Sood 2017-12-04 20:22 ` Tejun Heo 2017-12-04 20:22 ` Tejun Heo 2017-12-04 22:58 ` Tejun Heo 2017-12-04 23:01 ` Peter Zijlstra 2017-12-04 23:01 ` Peter Zijlstra 2017-12-08 9:40 ` Prateek Sood 2017-12-08 11:45 ` Prateek Sood 2017-12-08 11:45 ` Prateek Sood 2017-12-11 15:32 ` Tejun Heo 2017-12-11 15:32 ` Tejun Heo 2017-12-13 14:28 ` Prateek Sood 2017-12-13 15:40 ` Tejun Heo 2017-12-15 8:54 ` Prateek Sood 2017-12-15 8:54 ` Prateek Sood 2017-12-15 13:22 ` Tejun Heo 2017-12-15 19:06 ` Prateek Sood 2017-12-19 7:26 ` [PATCH] cgroup: Fix deadlock in cpu hotplug path Prateek Sood 2017-12-19 7:26 ` Prateek Sood 2017-12-19 13:39 ` Tejun Heo 2017-12-11 15:20 ` [PATCH] cgroup/cpuset: fix circular locking dependency Tejun Heo 2017-12-11 15:20 ` Tejun Heo 2017-12-13 7:50 ` Prateek Sood 2017-12-13 7:50 ` Prateek Sood 2017-12-13 16:06 ` Tejun Heo 2017-12-15 19:04 ` Prateek Sood [this message] 2017-12-15 19:04 ` Prateek Sood 2017-12-28 20:37 ` Prateek Sood 2017-12-28 20:37 ` Prateek Sood 2018-01-02 16:16 ` Tejun Heo 2018-01-02 17:44 ` Paul E. McKenney 2018-01-02 17:44 ` Paul E. McKenney 2018-01-02 18:01 ` Paul E. McKenney 2018-01-08 12:28 ` Tejun Heo 2018-01-08 12:28 ` Tejun Heo 2018-01-08 13:47 ` [PATCH wq/for-4.16 1/2] workqueue: separate out init_rescuer() Tejun Heo 2018-01-08 13:47 ` Tejun Heo 2018-01-08 13:47 ` [PATCH wq/for-4.16 2/2] workqueue: allow WQ_MEM_RECLAIM on early init workqueues Tejun Heo 2018-01-08 13:47 ` Tejun Heo 2018-01-08 22:52 ` [PATCH] cgroup/cpuset: fix circular locking dependency Paul E. McKenney 2018-01-08 22:52 ` Paul E. McKenney 2018-01-09 0:31 ` Paul E. McKenney 2018-01-09 3:42 ` Tejun Heo 2018-01-09 3:42 ` Tejun Heo 2018-01-09 4:20 ` Paul E. McKenney 2018-01-09 13:44 ` Tejun Heo 2018-01-09 15:21 ` Paul E. McKenney 2018-01-09 15:21 ` Paul E. McKenney 2018-01-09 15:37 ` Tejun Heo 2018-01-09 16:00 ` Paul E. McKenney 2018-01-09 16:00 ` Paul E. McKenney 2018-01-10 20:08 ` Paul E. McKenney 2018-01-10 21:41 ` Tejun Heo 2018-01-10 21:41 ` Tejun Heo 2018-01-10 22:10 ` Paul E. McKenney 2018-01-10 22:10 ` Paul E. McKenney 2018-01-15 12:02 ` Prateek Sood 2018-01-15 12:02 ` Prateek Sood 2018-01-16 16:27 ` Tejun Heo
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