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Groups > linux.kernel > #1226290
| From | Oleg Nesterov <oleg@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH cgroup/for-4.3-fixes 1/2] Revert "cgroup: simplify threadgroup locking" |
| Date | 2015-09-16 19:10 +0200 |
| Message-ID | <q9onv-2h2-5@gated-at.bofh.it> (permalink) |
| References | <q8XdE-4lR-29@gated-at.bofh.it> <q9nhN-vs-31@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 09/16, Tejun Heo wrote:
>
> From f9f9e7b776142fb1c0782cade004cc8e0147a199 Mon Sep 17 00:00:00 2001
> From: Tejun Heo <tj@kernel.org>
> Date: Wed, 16 Sep 2015 11:51:12 -0400
>
> This reverts commit b5ba75b5fc0e8404e2c50cb68f39bb6a53fc916f.
>
> d59cfc09c32a ("sched, cgroup: replace signal_struct->group_rwsem with
> a global percpu_rwsem") and b5ba75b5fc0e ("cgroup: simplify
> threadgroup locking") changed how cgroup synchronizes against task
> fork and exits so that it uses global percpu_rwsem instead of
> per-process rwsem; unfortunately, the write [un]lock paths of
> percpu_rwsem always involve synchronize_rcu_expedited() which turned
> out to be too expensive.
>
> Improvements for percpu_rwsem are scheduled to be merged in the coming
> v4.4-rc1 merge window which alleviates this issue. For now, revert
> the two commits to restore per-process rwsem. They will be re-applied
> for the v4.4-rc1 merge window.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Link: http://lkml.kernel.org/g/55F8097A.7000206@de.ibm.com
> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: stable@vger.kernel.org # v4.2+
So just in case, I agree. Perhaps we could merge the percpu_rwsem changes
in v4.3, but these patches look much safer for -stable.
Oleg.
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[4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-15 14:10 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Peter Zijlstra <peterz@infradead.org> - 2015-09-15 15:10 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-15 15:40 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Tejun Heo <tj@kernel.org> - 2015-09-15 16:00 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Paolo Bonzini <pbonzini@redhat.com> - 2015-09-15 18:50 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-15 19:40 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 10:40 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-16 11:00 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 11:20 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Oleg Nesterov <oleg@redhat.com> - 2015-09-16 14:30 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 14:40 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Oleg Nesterov <oleg@redhat.com> - 2015-09-16 14:50 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-16 15:00 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Tejun Heo <tj@kernel.org> - 2015-09-16 16:20 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 16:20 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-15 23:20 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Tejun Heo <tj@kernel.org> - 2015-09-15 23:30 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-15 23:40 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Tejun Heo <tj@kernel.org> - 2015-09-16 00:30 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-16 01:40 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Tejun Heo <tj@kernel.org> - 2015-09-16 03:30 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-09-16 06:40 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Tejun Heo <tj@kernel.org> - 2015-09-16 13:10 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-16 09:50 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-16 13:00 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Tejun Heo <tj@kernel.org> - 2015-09-16 13:10 +0200
Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-16 14:00 +0200
[PATCH cgroup/for-4.3-fixes 1/2] Revert "cgroup: simplify threadgroup locking" Tejun Heo <tj@kernel.org> - 2015-09-16 18:00 +0200
[PATCH cgroup/for-4.3-fixes 2/2] Revert "sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem" Tejun Heo <tj@kernel.org> - 2015-09-16 18:00 +0200
Re: [PATCH cgroup/for-4.3-fixes 1/2] Revert "cgroup: simplify threadgroup locking" Oleg Nesterov <oleg@redhat.com> - 2015-09-16 19:10 +0200
Re: [PATCH cgroup/for-4.3-fixes 1/2] Revert "cgroup: simplify threadgroup locking" Christian Borntraeger <borntraeger@de.ibm.com> - 2015-09-16 20:50 +0200
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