Re: [GIT PULL] workqueue fixes for v4.3-rc5

From	Christoph Lameter <cl@linux.com>
Newsgroups	linux.kernel
Subject	Re: [GIT PULL] workqueue fixes for v4.3-rc5
Date	2015-10-14 20:00 +0200
Message-ID	<qjyvf-5SM-3@gated-at.bofh.it> (permalink)
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On Wed, 14 Oct 2015, Linus Torvalds wrote:

> I don't think it's normally a problem. But mm/vmstat.c clearly *is*
> confused, and uses both "schedule_delayed_work_on()" and
> "schedule_delayed_work()" for the same work.

Well yes the schedule_delayed_work_on() call is from another cpu and the
schedule_delayed_work() from the same. No confusion there.

vmstat_update() is run from the cpu where the diffs have to be updated and
if it needs to reschedule itself it relies on schedule_delayed_work() to
stay on the same cpu.

The vmstat_shepherd needs to start work items on remote cpus and therefore
uses xx_work_on().

And yes this relies on work items being executed on the same cpu unless
the queue is decleared to be UNBOUND which is not the case here.

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Thread

[GIT PULL] workqueue fixes for v4.3-rc5 Tejun Heo <tj@kernel.org> - 2015-10-14 00:00 +0200
  Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 18:40 +0200
    Re: [GIT PULL] workqueue fixes for v4.3-rc5 Tejun Heo <tj@kernel.org> - 2015-10-14 19:00 +0200
      Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 19:40 +0200
        Re: [GIT PULL] workqueue fixes for v4.3-rc5 Christoph Lameter <cl@linux.com> - 2015-10-14 20:00 +0200
          Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 20:40 +0200
            Re: [GIT PULL] workqueue fixes for v4.3-rc5 Christoph Lameter <cl@linux.com> - 2015-10-14 21:00 +0200
            Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 21:10 +0200
        Re: [GIT PULL] workqueue fixes for v4.3-rc5 Tejun Heo <tj@kernel.org> - 2015-10-14 21:10 +0200
          Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 21:20 +0200
            Re: [GIT PULL] workqueue fixes for v4.3-rc5 Tejun Heo <tj@kernel.org> - 2015-10-14 21:40 +0200
              Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 22:20 +0200
                Re: [GIT PULL] workqueue fixes for v4.3-rc5 Tejun Heo <tj@kernel.org> - 2015-10-14 22:30 +0200
                Re: [PATCH] vmstat_update: ensure work remains on the same core Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-16 22:00 +0200
    Re: [GIT PULL] workqueue fixes for v4.3-rc5 Christoph Lameter <cl@linux.com> - 2015-10-14 20:10 +0200
      Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 20:50 +0200
        Re: [GIT PULL] workqueue fixes for v4.3-rc5 Christoph Lameter <cl@linux.com> - 2015-10-14 21:00 +0200
          Re: [GIT PULL] workqueue fixes for v4.3-rc5 Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-14 21:20 +0200

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