From: Tejun Heo <tj@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Sasha Levin <sasha.levin@oracle.com>,
Alexei Starovoitov <ast@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Christoph Lameter <cl@linux.com>,
Linux-MM layout <linux-mm@kvack.org>,
Marco Grassi <marco.gra@gmail.com>
Subject: Re: [PATCH percpu/for-4.7-fixes 1/2] percpu: fix synchronization between chunk->map_extend_work and chunk destruction
Date: Thu, 26 May 2016 15:21:54 -0400 [thread overview]
Message-ID: <20160526192154.GC23194@mtj.duckdns.org> (raw)
In-Reply-To: <ced75777-583e-9444-c59f-6cdeb468f1bf@suse.cz>
Hello,
On Thu, May 26, 2016 at 11:19:06AM +0200, Vlastimil Babka wrote:
> > if (is_atomic) {
> > margin = 3;
> >
> > if (chunk->map_alloc <
> > - chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW &&
> > - pcpu_async_enabled)
> > - schedule_work(&chunk->map_extend_work);
> > + chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW) {
> > + if (list_empty(&chunk->map_extend_list)) {
> So why this list_empty condition? Doesn't it deserve a comment then? And
Because doing list_add() twice corrupts the list. I'm not sure that
deserves a comment. We can do list_move() instead but that isn't
necessarily better.
> isn't using a list an overkill in that case?
That would require rebalance work to scan all chunks whenever it's
scheduled and if a lot of atomic allocations are taking place, it has
some possibility to become expensive with a lot of chunks.
Thanks.
--
tejun
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next prev parent reply other threads:[~2016-05-26 19:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <5713C0AD.3020102@oracle.com>
[not found] ` <20160417172943.GA83672@ast-mbp.thefacebook.com>
2016-05-23 12:01 ` bpf: use-after-free in array_map_alloc Vlastimil Babka
2016-05-23 12:07 ` Vlastimil Babka
2016-05-23 21:35 ` Tejun Heo
2016-05-23 22:13 ` Alexei Starovoitov
2016-05-24 8:40 ` Vlastimil Babka
2016-05-24 15:30 ` Tejun Heo
2016-05-24 19:04 ` Tejun Heo
2016-05-24 20:43 ` Alexei Starovoitov
2016-05-25 15:44 ` [PATCH percpu/for-4.7-fixes 1/2] percpu: fix synchronization between chunk->map_extend_work and chunk destruction Tejun Heo
2016-05-26 9:19 ` Vlastimil Babka
2016-05-26 19:21 ` Tejun Heo [this message]
2016-05-26 20:48 ` Vlastimil Babka
2016-05-25 15:45 ` [PATCH percpu/for-4.7-fixes 2/2] percpu: fix synchronization between synchronous map extension " Tejun Heo
2016-05-26 9:48 ` Vlastimil Babka
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