From: Petr Mladek <pmladek@suse.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-mm@kvack.org,
"Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@suse.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] mm/page_alloc: Use write_seqlock_irqsave() instead write_seqlock() + local_irq_save().
Date: Wed, 21 Jun 2023 14:40:50 +0200 [thread overview]
Message-ID: <ZJLv0jaOzFbkN6Wz@alley> (raw)
In-Reply-To: <0e9fc992-8e05-2e63-b3b1-d8d3ce89fc16@I-love.SAKURA.ne.jp>
On Wed 2023-06-21 20:33:35, Tetsuo Handa wrote:
> On 2023/06/21 19:40, Sebastian Andrzej Siewior wrote:
> > printk_deferred_enter() has to be invoked in non-migrate-able context to
> > ensure that deferred printing is enabled and disabled on the same CPU.
>
> I can't catch. local_irq_save(flags); makes non-migrate-able context
> because sleeping is not allowed while IRQ is disabled, doesn't it?
>
> > This is the case after zonelist_update_seq has been acquired.
> >
> > Acquire zonelist_update_seq with write_seqlock_irqsave() and then defer
> > printk output.
>
> What guarantees that write_seqlock_irqsave() never calls printk()
> (e.g. lockdep warning) before printk_deferred_enter() takes effect?
I think that we should explicitly disable preemption in
printk_deferred_enter(). The disabled interrupts are not
strictly necessary.
I am going to resurrect the patch
https://lore.kernel.org/r/20230419074210.17646-1-pmladek@suse.com
and add the preempt_disable()/enable() at the same time.
Is this going to work for you?
Best Regards,
Petr
next prev parent reply other threads:[~2023-06-21 12:40 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 10:40 Sebastian Andrzej Siewior
2023-06-21 10:59 ` Michal Hocko
2023-06-21 11:16 ` Sebastian Andrzej Siewior
2023-06-21 11:49 ` Michal Hocko
2023-06-21 13:11 ` Sebastian Andrzej Siewior
2023-06-21 13:22 ` Michal Hocko
2023-06-21 13:25 ` Sebastian Andrzej Siewior
2023-06-21 11:14 ` David Hildenbrand
2023-06-21 11:33 ` Tetsuo Handa
2023-06-21 12:40 ` Petr Mladek [this message]
2023-06-21 13:08 ` Sebastian Andrzej Siewior
2023-06-21 13:06 ` Sebastian Andrzej Siewior
2023-06-21 13:32 ` Tetsuo Handa
2023-06-21 14:34 ` Sebastian Andrzej Siewior
2023-06-21 14:50 ` Tetsuo Handa
2023-06-21 23:24 ` Tetsuo Handa
2023-06-22 7:18 ` Michal Hocko
2023-06-22 10:58 ` Tetsuo Handa
2023-06-22 12:09 ` Michal Hocko
2023-06-22 13:36 ` Tetsuo Handa
2023-06-22 14:11 ` Petr Mladek
2023-06-22 14:28 ` Tetsuo Handa
2023-06-23 9:35 ` Sebastian Andrzej Siewior
2023-06-22 15:04 ` Petr Mladek
2023-06-22 15:43 ` Tetsuo Handa
2023-06-23 9:45 ` Sebastian Andrzej Siewior
2023-06-23 9:51 ` Tetsuo Handa
2023-06-23 10:11 ` Sebastian Andrzej Siewior
2023-06-23 10:36 ` Tetsuo Handa
2023-06-23 12:44 ` Sebastian Andrzej Siewior
2023-06-23 12:57 ` Michal Hocko
2023-06-23 10:53 ` Petr Mladek
2023-06-23 11:16 ` Tetsuo Handa
2023-06-23 13:31 ` Sebastian Andrzej Siewior
2023-06-23 15:38 ` Petr Mladek
2023-06-23 16:04 ` Sebastian Andrzej Siewior
2023-06-23 9:31 ` Sebastian Andrzej Siewior
2023-06-23 7:27 ` Sebastian Andrzej Siewior
2023-06-21 15:38 ` Petr Mladek
2023-06-23 8:12 ` Sebastian Andrzej Siewior
2023-06-23 9:21 ` Michal Hocko
2023-06-23 9:58 ` Sebastian Andrzej Siewior
2023-06-23 10:43 ` Michal Hocko
2023-06-23 10:45 ` Sebastian Andrzej Siewior
2023-06-23 10:50 ` Sebastian Andrzej Siewior
2023-06-23 11:32 ` Michal Hocko
2023-06-23 10:40 ` Petr Mladek
2023-06-23 13:24 ` Sebastian Andrzej Siewior
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZJLv0jaOzFbkN6Wz@alley \
--to=pmladek@suse.com \
--cc=akpm@linux-foundation.org \
--cc=bigeasy@linutronix.de \
--cc=lgoncalv@redhat.com \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@suse.com \
--cc=penguin-kernel@i-love.sakura.ne.jp \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox