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Re: mm: deadlock between get_online_cpus/pcpu_alloc

From Mel Gorman <mgorman@techsingularity.net>
Newsgroups linux.kernel
Subject Re: mm: deadlock between get_online_cpus/pcpu_alloc
Date 2017-02-07 11:30 +0100
Message-ID <t8bc6-1Av-7@gated-at.bofh.it> (permalink)
References (3 earlier) <t7WZs-HE-15@gated-at.bofh.it> <t7ZDY-2rk-17@gated-at.bofh.it> <t89Dk-vJ-15@gated-at.bofh.it> <t8azn-16x-5@gated-at.bofh.it> <t8aJ4-1am-19@gated-at.bofh.it>
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On Tue, Feb 07, 2017 at 10:49:28AM +0100, Vlastimil Babka wrote:
> On 02/07/2017 10:43 AM, Mel Gorman wrote:
> > If I'm reading this right, a hot-remove will set the pool POOL_DISASSOCIATED
> > and unbound. A workqueue queued for draining get migrated during hot-remove
> > and a drain operation will execute twice on a CPU -- one for what was
> > queued and a second time for the CPU it was migrated from. It should still
> > work with flush_work which doesn't appear to block forever if an item
> > got migrated to another workqueue. The actual drain workqueue function is
> > using the CPU ID it's currently running on so it shouldn't get confused.
> 
> Is the worker that will process this migrated workqueue also guaranteed
> to be pinned to a cpu for the whole work, though? drain_local_pages()
> needs that guarantee.
> 

It should be by running on a workqueue handler bound to that CPU (queued
on wq->cpu_pwqs in __queue_work)

-- 
Mel Gorman
SUSE Labs

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Thread

Re: mm: deadlock between get_online_cpus/pcpu_alloc Dmitry Vyukov <dvyukov@google.com> - 2017-02-06 20:20 +0100
  Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-06 23:10 +0100
    Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 09:50 +0100
      Re: mm: deadlock between get_online_cpus/pcpu_alloc Vlastimil Babka <vbabka@suse.cz> - 2017-02-07 10:30 +0100
        Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 10:50 +0100
        Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 11:00 +0100
        Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 11:50 +0100
          Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 12:20 +0100
      Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 10:50 +0100
        Re: mm: deadlock between get_online_cpus/pcpu_alloc Vlastimil Babka <vbabka@suse.cz> - 2017-02-07 11:00 +0100
          Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 11:10 +0100
          Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 11:30 +0100
            Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 11:40 +0100
              Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 12:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 12:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Vlastimil Babka <vbabka@suse.cz> - 2017-02-07 13:00 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 13:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 13:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Vlastimil Babka <vbabka@suse.cz> - 2017-02-07 13:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 13:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Vlastimil Babka <vbabka@suse.cz> - 2017-02-07 15:00 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 15:00 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 15:20 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 16:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 17:30 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 17:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-07 18:00 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-07 23:30 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-08 08:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-08 13:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-08 13:30 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-08 13:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-08 15:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Peter Zijlstra <peterz@infradead.org> - 2017-02-08 18:00 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-08 15:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-08 16:30 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-08 17:30 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-08 19:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-09 04:20 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-09 12:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-09 15:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-09 16:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-09 16:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-09 17:20 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-09 18:30 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-09 18:50 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-09 20:20 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-10 19:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-08 18:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Christoph Lameter <cl@linux.com> - 2017-02-08 16:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Tejun Heo <tj@kernel.org> - 2017-02-07 18:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 21:40 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Mel Gorman <mgorman@techsingularity.net> - 2017-02-07 14:10 +0100
                Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 14:50 +0100
    Re: mm: deadlock between get_online_cpus/pcpu_alloc Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-02-07 12:30 +0100
  Re: mm: deadlock between get_online_cpus/pcpu_alloc Michal Hocko <mhocko@kernel.org> - 2017-02-07 09:50 +0100
  Re: mm: deadlock between get_online_cpus/pcpu_alloc Thomas Gleixner <tglx@linutronix.de> - 2017-02-07 23:40 +0100

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