LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Mike Galbraith <efault@gmx.de>
To: Vlastimil Babka <vbabka@suse.cz>, Clark Williams <williams@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	RT <linux-rt-users@vger.kernel.org>
Subject: Re: [ANNOUNCE] v5.14-rc5-rt8
Date: Sun, 15 Aug 2021 15:03:35 +0200	[thread overview]
Message-ID: <7ad059482e56e88bfbe13830cfa06dffee9d071f.camel@gmx.de> (raw)
In-Reply-To: <c92fc2cb-03cd-d6a2-fb4a-7bc33e94e391@suse.cz>

On Sun, 2021-08-15 at 11:35 +0200, Vlastimil Babka wrote:
> On 8/15/21 6:17 AM, Mike Galbraith wrote:
> > On Sat, 2021-08-14 at 21:08 +0200, Vlastimil Babka wrote:
> > >
> > > Aha! That's helpful. Hopefully it's just a small issue where we
> > > opportunistically test flags on a page that's protected by the local
> > > lock we didn't take yet, and I didn't realize there's the VM_BUG_ON
> > > which can trigger if our page went away (which we would have realized
> > > after taking the lock).
> >
> > Speaking of optimistic peeking perhaps going badly, why is the below
> > not true?  There's protection against ->partial going disappearing
> > during a preemption... but can't it just as easily appear, so where is
> > that protection?
>
> If it appears, it appears, we don't care, we just leave it there and
> won't use it.
>
> > If the other side of that window is safe, it could use a comment so
> > dummies reading this code don't end up asking mm folks why the heck
> > they don't just take the darn lock and be done with it instead of tap
> > dancing all around thething :)
>
> Well, with your patch, ->partial might appear just after the unlock, so
> does that really change anything?

Viewed from pov consumption is optional, it makes sense.

	-Mike




  reply	other threads:[~2021-08-15 13:03 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-10 16:37 Sebastian Andrzej Siewior
2021-08-12 20:18 ` Clark Williams
2021-08-12 20:45   ` Vlastimil Babka
2021-08-12 21:24     ` Clark Williams
2021-08-12 21:30       ` Vlastimil Babka
2021-08-12 21:44         ` Clark Williams
2021-08-14 19:08           ` Vlastimil Babka
2021-08-15  3:13             ` Mike Galbraith
2021-08-15  9:01               ` Mike Galbraith
2021-08-15  4:17             ` Mike Galbraith
2021-08-15  9:35               ` Vlastimil Babka
2021-08-15 13:03                 ` Mike Galbraith [this message]
2021-08-12 21:36   ` Vlastimil Babka
2021-08-12 21:47     ` Clark Williams
2021-08-13 10:56   ` Mike Galbraith
2021-08-14  5:33     ` Mike Galbraith
2021-08-14 18:28       ` Vlastimil Babka
2021-08-15  1:26         ` Mike Galbraith

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=7ad059482e56e88bfbe13830cfa06dffee9d071f.camel@gmx.de \
    --to=efault@gmx.de \
    --cc=bigeasy@linutronix.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rt-users@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=vbabka@suse.cz \
    --cc=williams@redhat.com \
    --subject='Re: [ANNOUNCE] v5.14-rc5-rt8' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).