From: Michal Hocko <mhocko@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>,
Qian Cai <cai@lca.pw>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Petr Mladek <pmladek@suse.com>,
akpm@linux-foundation.org, rostedt@goodmis.org,
peterz@infradead.org, linux-mm@kvack.org,
john.ogness@linutronix.de, david@redhat.com,
linux-kernel@vger.kernel.org,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>
Subject: Re: [PATCH v2] mm/page_isolation: fix a deadlock with printk()
Date: Thu, 10 Oct 2019 10:37:10 +0200 [thread overview]
Message-ID: <20191010083710.GF18412@dhcp22.suse.cz> (raw)
In-Reply-To: <20191010081629.GA120986@jagdpanzerIV>
On Thu 10-10-19 17:16:29, Sergey Senozhatsky wrote:
> On (10/10/19 09:40), Michal Hocko wrote:
> [..]
> > > > Considering that console.write is called from essentially arbitrary code
> > > > path IIUC then all the locks used in this path should be pretty much
> > > > tail locks or console internal ones without external dependencies.
> > >
> > > That's a good expectation, but I guess it's not always the case.
> > >
> > > One example might be NET console - net subsystem locks, net device
> > > drivers locks, maybe even some MM locks (skb allocations?).
> >
> > I am not familiar with the netconsole code TBH. If there is absolutely
> > no way around that then we might have to bite a bullet and consider some
> > of MM locks a land of no printk.
>
> So this is what netconsole does (before we pass on udp to net device
> driver code, which *may be* can do more allocations, I don't know):
>
> write_msg()
> netpoll_send_udp()
> find_skb()
> alloc_skb(len, GFP_ATOMIC)
> kmem_cache_alloc_node()
>
> You are the right person to ask this question to - how many MM
> locks are involved when we do GFP_ATOMIC kmem_cache allocation?
> Is there anything to be concerned about?
At least zone->lock might involved. Maybe even more.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-10-10 8:37 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 22:26 [PATCH v2] mm/page_isolation: fix a deadlock with printk() Qian Cai
2019-10-07 8:07 ` Michal Hocko
2019-10-07 9:05 ` Petr Mladek
2019-10-07 11:33 ` Michal Hocko
2019-10-07 12:34 ` Qian Cai
2019-10-07 11:04 ` Qian Cai
2019-10-07 11:37 ` Michal Hocko
2019-10-07 12:11 ` Qian Cai
2019-10-07 12:43 ` Michal Hocko
2019-10-07 13:07 ` Qian Cai
2019-10-07 14:10 ` Petr Mladek
2019-10-07 14:30 ` Petr Mladek
2019-10-07 14:49 ` Michal Hocko
2019-10-08 7:43 ` Petr Mladek
2019-10-08 8:27 ` Michal Hocko
2019-10-08 12:56 ` Christian Borntraeger
2019-10-08 16:08 ` Qian Cai
2019-10-08 18:35 ` Michal Hocko
2019-10-08 19:06 ` Qian Cai
2019-10-08 19:17 ` Michal Hocko
2019-10-08 19:35 ` Qian Cai
2019-10-09 11:49 ` Petr Mladek
2019-10-09 13:06 ` Qian Cai
2019-10-09 13:27 ` Michal Hocko
2019-10-09 13:43 ` Qian Cai
2019-10-09 13:51 ` Michal Hocko
2019-10-09 14:19 ` Qian Cai
2019-10-09 14:34 ` Michal Hocko
2019-10-09 15:08 ` Qian Cai
2019-10-09 16:23 ` Michal Hocko
2019-10-09 16:23 ` Michal Hocko
2019-10-10 9:01 ` Qian Cai
2019-10-10 10:59 ` Michal Hocko
2019-10-10 13:11 ` Qian Cai
2019-10-10 14:18 ` Michal Hocko
2019-10-10 14:47 ` Qian Cai
2019-10-10 17:30 ` Michal Hocko
2019-10-10 17:48 ` Qian Cai
2019-10-10 18:06 ` Michal Hocko
2019-10-10 18:59 ` David Hildenbrand
2019-10-09 14:24 ` Petr Mladek
2019-10-09 14:46 ` Qian Cai
2019-10-10 7:57 ` Petr Mladek
2019-10-09 11:39 ` Petr Mladek
2019-10-09 13:56 ` Peter Oberparleiter
2019-10-09 14:26 ` Michal Hocko
2019-10-10 5:12 ` Sergey Senozhatsky
2019-10-10 7:40 ` Michal Hocko
2019-10-10 8:16 ` Sergey Senozhatsky
2019-10-10 8:37 ` Michal Hocko [this message]
2019-10-10 8:21 ` Petr Mladek
2019-10-10 8:39 ` Sergey Senozhatsky
2019-10-10 11:11 ` Petr Mladek
2019-10-09 15:25 ` Qian Cai
2019-10-09 15:25 ` Qian Cai
2019-10-07 14:59 ` Qian Cai
2019-10-07 15:12 ` Michal Hocko
2019-10-07 15:33 ` Qian Cai
2019-10-08 8:15 ` Petr Mladek
2019-10-08 9:32 ` Qian Cai
2019-10-08 13:13 ` Steven Rostedt
2019-10-08 13:23 ` Qian Cai
2019-10-08 13:33 ` Steven Rostedt
2019-10-08 13:42 ` Petr Mladek
2019-10-08 13:48 ` Michal Hocko
2019-10-08 14:03 ` Qian Cai
2019-10-08 14:08 ` Michal Hocko
2019-10-08 8:40 ` Michal Hocko
2019-10-08 10:04 ` Qian Cai
2019-10-08 10:39 ` Michal Hocko
2019-10-08 12:00 ` Qian Cai
2019-10-08 12:39 ` Michal Hocko
2019-10-08 13:06 ` Qian Cai
2019-10-08 13:37 ` Michal Hocko
2019-10-08 13:08 ` Petr Mladek
2019-10-08 13:33 ` Qian Cai
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