From: Thomas Gleixner <tglx@linutronix.de>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
LKML <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [PATCH] mm/memory-hotplug: Switch locking to a percpu rwsem
Date: Mon, 3 Jul 2017 21:57:18 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1707032156320.2993@nanos> (raw)
In-Reply-To: <20170703163204.GE11848@dhcp22.suse.cz>
On Mon, 3 Jul 2017, Michal Hocko wrote:
> On Fri 30-06-17 12:15:21, Thomas Gleixner wrote:
> [...]
> > Sure. Just to make you to mull over more stuff, find below the patch which
> > moves all of this to use the cpuhotplug lock.
> >
> > Thanks,
> >
> > tglx
> >
> > 8<--------------------
> > Subject: mm/memory-hotplug: Use cpu hotplug lock
> > From: Thomas Gleixner <tglx@linutronix.de>
> > Date: Thu, 29 Jun 2017 16:30:00 +0200
> >
> > Most place which take the memory hotplug lock take the cpu hotplug lock as
> > well. Avoid the double locking and use the cpu hotplug lock for both.
>
> Hmm, I am usually not a fan of locks conflating because it is then less
> clear what the lock actually protects. Memory and cpu hotplugs should
> be largely independent so I am not sure this patch simplify things a
> lot. It is nice to see few lines go away but I am little bit worried
> that we will enventually develop a separate locking again in future for
> some weird memory hotplug usecases.
Fair enough.
>
> > Not-Yet-Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> [...]
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> [...]
> > @@ -2138,7 +2114,7 @@ void __ref remove_memory(int nid, u64 st
> >
> > try_offline_node(nid);
> >
> > - mem_hotplug_done();
> > + cpus_write_lock();
>
> unlock you meant here, right?
Doh, -ENOQUILTREFRESH
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next prev parent reply other threads:[~2017-07-03 19:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-29 16:11 [PATCH] mm/memory-hotplug: Switch locking to a percpu rwsem Thomas Gleixner
2017-06-30 9:27 ` Michal Hocko
2017-06-30 10:15 ` Thomas Gleixner
2017-06-30 11:49 ` Andrey Ryabinin
2017-06-30 13:00 ` Thomas Gleixner
2017-06-30 15:56 ` Andrey Ryabinin
2017-07-03 16:32 ` Michal Hocko
2017-07-03 19:57 ` Thomas Gleixner [this message]
2017-07-03 12:41 ` Vladimir Davydov
2017-07-03 16:38 ` Michal Hocko
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