From: Andrea Arcangeli <aarcange@redhat.com>
To: Greg KH <greg@kroah.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
mtk.manpages@gmail.com, linux-man@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: open(2) says O_DIRECT works on 512 byte boundries?
Date: Tue, 3 Feb 2009 16:01:12 +0100 [thread overview]
Message-ID: <20090203150111.GA20323@random.random> (raw)
In-Reply-To: <20090203035012.GC1867@kroah.com>
On Mon, Feb 02, 2009 at 07:50:12PM -0800, Greg KH wrote:
> On Mon, Feb 02, 2009 at 11:08:56PM +0100, Andrea Arcangeli wrote:
> > Hi Greg!
> >
> > > Thanks for the pointers, I'll go read the thread and follow up there.
> >
> > If you also run into this final fix is attached below. Porting to
> > mainline is a bit hard because of gup-fast... Perhaps we can use mmu
> > notifiers to fix gup-fast... need to think more about it then I'll
> > post something.
> >
> > Please help testing the below on pre-gup-fast kernels, thanks!
>
> Thanks a lot for the patch, I'll try this out tomorrow.
before testing I recommend to make this change:
- if ((flags & FOLL_WRITE) && PageAnon(page) && !PageGUP(page))
+ if (PageAnon(page) && !PageGUP(page))
If gup triggers cow, gup clears FOLL_WRITE from foll_flags before
calling follow_page again, I think that's why it didn't work right for
everyone, it just couldn't work right if FOLL_WRITE was going away
before the last follow_page run. I wanted to set PG_gup only for
gup(write=1) and not for gup(write=0) but that optimization that
clears FOLL_WRITE prevents the above to work right, so the simple
solution is to always set PG_gup, it won't make a big difference.
I'm looking at the hugetlb cow before posting an update...
next prev parent reply other threads:[~2009-02-03 15:01 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-28 21:33 open(2) says O_DIRECT works on 512 byte boundries? Greg KH
2009-01-29 0:41 ` Robert Hancock
[not found] ` <20090129011758.GA26534@kroah.com>
2009-01-29 2:59 ` Michael Kerrisk
2009-01-29 3:13 ` Greg KH
2009-01-29 15:40 ` Jeff Moyer
2009-01-30 6:16 ` Greg KH
2009-01-29 5:13 ` KAMEZAWA Hiroyuki
2009-01-29 7:10 ` KOSAKI Motohiro
2009-01-30 6:17 ` Greg KH
2009-02-02 22:08 ` Andrea Arcangeli
2009-02-03 1:29 ` KAMEZAWA Hiroyuki
2009-02-03 2:31 ` Andrea Arcangeli
2009-02-03 2:55 ` KAMEZAWA Hiroyuki
2009-02-03 3:42 ` KAMEZAWA Hiroyuki
2009-02-06 17:55 ` Andrea Arcangeli
2009-02-03 3:50 ` Greg KH
2009-02-03 15:01 ` Andrea Arcangeli [this message]
2009-02-03 4:13 ` KAMEZAWA Hiroyuki
2009-02-03 4:38 ` KAMEZAWA Hiroyuki
2009-02-03 15:08 ` Andrea Arcangeli
2009-02-04 23:41 ` Greg KH
2009-02-06 17:54 ` Andrea Arcangeli
2009-02-06 18:38 ` Andrea Arcangeli
2009-02-07 13:32 ` Izik Eidus
2009-02-07 15:33 ` Andrea Arcangeli
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=20090203150111.GA20323@random.random \
--to=aarcange@redhat.com \
--cc=greg@kroah.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-man@vger.kernel.org \
--cc=mtk.manpages@gmail.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 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).