From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Waiman Long <longman@redhat.com>
Cc: Roman Gushchin <guro@fb.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>, Rik van Riel <riel@surriel.com>,
Shakeel Butt <shakeelb@google.com>,
Christoph Lameter <cl@linux.com>,
cgroups@vger.kernel.org
Subject: Re: [PATCH v5 5/7] mm: rework non-root kmem_cache lifecycle management
Date: Tue, 28 May 2019 20:39:59 +0300 [thread overview]
Message-ID: <20190528173959.h4hq55b3ajlfpjrk@esperanza> (raw)
In-Reply-To: <96b8a923-49e4-f13e-b1e3-3df4598d849e@redhat.com>
On Tue, May 28, 2019 at 01:37:50PM -0400, Waiman Long wrote:
> On 5/28/19 1:08 PM, Vladimir Davydov wrote:
> >> static void flush_memcg_workqueue(struct kmem_cache *s)
> >> {
> >> + /*
> >> + * memcg_params.dying is synchronized using slab_mutex AND
> >> + * memcg_kmem_wq_lock spinlock, because it's not always
> >> + * possible to grab slab_mutex.
> >> + */
> >> mutex_lock(&slab_mutex);
> >> + spin_lock(&memcg_kmem_wq_lock);
> >> s->memcg_params.dying = true;
> >> + spin_unlock(&memcg_kmem_wq_lock);
> > I would completely switch from the mutex to the new spin lock -
> > acquiring them both looks weird.
> >
> >> mutex_unlock(&slab_mutex);
> >>
> >> /*
>
> There are places where the slab_mutex is held and sleeping functions
> like kvzalloc() are called. I understand that taking both mutex and
> spinlocks look ugly, but converting all the slab_mutex critical sections
> to spinlock critical sections will be a major undertaking by itself. So
> I would suggest leaving that for now.
I didn't mean that. I meant taking spin_lock wherever we need to access
the 'dying' flag, even if slab_mutex is held. So that we don't need to
take mutex_lock in flush_memcg_workqueue, where it's used solely for
'dying' synchronization.
next prev parent reply other threads:[~2019-05-28 17:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 20:07 [PATCH v5 0/7] mm: reparent slab memory on cgroup removal Roman Gushchin
2019-05-21 20:07 ` [PATCH v5 1/7] mm: postpone kmem_cache memcg pointer initialization to memcg_link_cache() Roman Gushchin
2019-05-28 17:14 ` Vladimir Davydov
2019-05-28 21:56 ` Johannes Weiner
2019-05-21 20:07 ` [PATCH v5 2/7] mm: generalize postponed non-root kmem_cache deactivation Roman Gushchin
2019-05-28 17:11 ` Vladimir Davydov
2019-05-21 20:07 ` [PATCH v5 3/7] mm: introduce __memcg_kmem_uncharge_memcg() Roman Gushchin
2019-05-21 20:07 ` [PATCH v5 4/7] mm: unify SLAB and SLUB page accounting Roman Gushchin
2019-05-28 17:12 ` Vladimir Davydov
2019-05-28 22:00 ` Johannes Weiner
2019-05-21 20:07 ` [PATCH v5 5/7] mm: rework non-root kmem_cache lifecycle management Roman Gushchin
2019-05-28 17:08 ` Vladimir Davydov
2019-05-28 17:37 ` Waiman Long
2019-05-28 17:39 ` Vladimir Davydov [this message]
2019-05-28 17:41 ` Waiman Long
2019-05-28 18:00 ` Vladimir Davydov
2019-05-28 22:03 ` Johannes Weiner
2019-05-28 22:28 ` Roman Gushchin
2019-05-21 20:07 ` [PATCH v5 6/7] mm: reparent slab memory on cgroup removal Roman Gushchin
2019-05-28 18:33 ` Vladimir Davydov
2019-05-28 19:58 ` Roman Gushchin
2019-05-28 20:11 ` Vladimir Davydov
2019-05-28 21:52 ` Roman Gushchin
2019-05-28 22:16 ` Johannes Weiner
2019-05-21 20:07 ` [PATCH v5 7/7] mm: fix /proc/kpagecgroup interface for slab pages Roman Gushchin
2019-05-28 17:38 ` Vladimir Davydov
2019-05-22 21:43 ` [PATCH v5 0/7] mm: reparent slab memory on cgroup removal Roman Gushchin
2019-05-22 21:59 ` Andrew Morton
2019-05-22 22:23 ` Roman Gushchin
2019-05-28 7:01 ` Michal Hocko
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