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
next prev parent 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 [ANNOUNCE] v5.14-rc5-rt8 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 \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.