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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jan Kara <jack@suse.cz>
Cc: Andreas Gruenbacher <agruenba@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christoph Hellwig <hch@infradead.org>,
	"Darrick J. Wong" <djwong@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	cluster-devel <cluster-devel@redhat.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	ocfs2-devel@oss.oracle.com
Subject: Re: [PATCH v3 1/7] iov_iter: Introduce fault_in_iov_iter helper
Date: Mon, 26 Jul 2021 10:15:31 -0700	[thread overview]
Message-ID: <CAHk-=wgqOZmRT_gmAS+K9sA7EYCKM9BYzvJMhy1_P6JaaVGvfA@mail.gmail.com> (raw)
In-Reply-To: <20210726163326.GK20621@quack2.suse.cz>

On Mon, Jul 26, 2021 at 9:33 AM Jan Kara <jack@suse.cz> wrote:
>
> On Fri 23-07-21 22:58:34, Andreas Gruenbacher wrote:
> > +     gup_flags = FOLL_TOUCH | FOLL_POPULATE;
>
> I don't think FOLL_POPULATE makes sense here. It makes sense only with
> FOLL_MLOCK and determines whether mlock(2) should fault in missing pages or
> not.

Yeah, it won't hurt, but FOLL_POPULATE doesn't actually do anything
unless FOLL_MLOCK is set. It is, as you say, a magic flag just for
mlock.

The only ones that should matter are FOLL_WRITE (for obvious reasons)
and FOLL_TOUCH (to set the accessed and dirty bits, rather than just
th protection bits)

                   Linus

  reply	other threads:[~2021-07-26 17:27 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 20:58 [PATCH v3 0/7] gfs2: Fix mmap + page fault deadlocks Andreas Gruenbacher
2021-07-23 20:58 ` [PATCH v3 1/7] iov_iter: Introduce fault_in_iov_iter helper Andreas Gruenbacher
2021-07-23 23:40   ` Linus Torvalds
2021-07-24  7:51     ` Andreas Grünbacher
2021-07-24  1:52   ` Al Viro
2021-07-24  8:05     ` Andreas Grünbacher
2021-07-26 16:33   ` Jan Kara
2021-07-26 17:15     ` Linus Torvalds [this message]
2021-07-23 20:58 ` [PATCH v3 2/7] gfs2: Add wrapper for iomap_file_buffered_write Andreas Gruenbacher
2021-07-23 20:58 ` [PATCH v3 3/7] gfs2: Fix mmap + page fault deadlocks for buffered I/O Andreas Gruenbacher
2021-07-23 20:58 ` [PATCH v3 4/7] iomap: Fix iomap_dio_rw return value for user copies Andreas Gruenbacher
2021-07-23 20:58 ` [PATCH v3 5/7] iomap: Support restarting direct I/O requests after user copy failures Andreas Gruenbacher
2021-07-26 17:19   ` Jan Kara
     [not found]     ` <CAHpGcMLtQ1=WOT1mTUS4=iWBwHLQ-EBzY=+XuSGJfu4gVPYTLw@mail.gmail.com>
2021-07-26 18:08       ` Jan Kara
2021-07-23 20:58 ` [PATCH v3 6/7] iov_iter: Introduce noio flag to disable page faults Andreas Gruenbacher
2021-07-23 20:58 ` [PATCH v3 7/7] gfs2: Fix mmap + page fault deadlocks for direct I/O Andreas Gruenbacher
2021-07-26 17:02   ` Jan Kara
     [not found]     ` <CAHpGcMLOZhZ7tGrY7rcYWUwx12sY884T=eC-Ckna63PBmF=zwA@mail.gmail.com>
2021-07-26 18:00       ` Jan Kara

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