From: Jens Axboe <jens.axboe@oracle.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [patch] splice mmap_sem deadlock
Date: Fri, 28 Sep 2007 21:30:18 +0200 [thread overview]
Message-ID: <20070928193017.GC11717@kernel.dk> (raw)
In-Reply-To: <alpine.LFD.0.999.0709281120220.3579@woody.linux-foundation.org>
On Fri, Sep 28 2007, Linus Torvalds wrote:
>
>
> On Fri, 28 Sep 2007, Jens Axboe wrote:
> >
> > It actually looks like it was buggy from day 1 there, unfortunately. The
> > code is from april 2006 and used down_read() even then.
>
> I was thinking of my *original* patch from way back when. But that one
> didn't actually do any of that stuff so no, it wasn't from there.
Right, vmsplice() wasn't part of the original stuff.
> > So can you apply Nicks patch
>
> I don't even have it, I only have a quoted-corrupted version of it. I
> wasn't originally cc'd.
Hmm, part of me doesn't like this patch, since we now end up beating on
mmap_sem for each part of the vec. It's fine for a stable patch, but how
about
- prefaulting the iovec
- using __get_user()
- only dropping/regrabbing the lock if we have to fault
?
--
Jens Axboe
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next prev parent reply other threads:[~2007-09-28 19:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-28 16:00 [patch] splice mmap_sem deadlock Nick Piggin
2007-09-28 17:31 ` Jens Axboe
2007-09-28 18:10 ` Linus Torvalds
2007-09-28 18:15 ` Jens Axboe
2007-09-28 18:23 ` Linus Torvalds
2007-09-28 19:30 ` Jens Axboe [this message]
2007-09-28 20:02 ` Linus Torvalds
2007-09-28 20:08 ` Linus Torvalds
2007-09-29 6:37 ` Jens Axboe
2007-10-01 12:03 ` Jens Axboe
2007-10-01 15:11 ` Linus Torvalds
2007-10-01 15:45 ` Balbir Singh
2007-10-01 16:11 ` Linus Torvalds
2007-10-01 18:19 ` Balbir Singh
2007-10-01 17:33 ` Jens Axboe
2007-09-29 13:10 ` Nick Piggin
2007-09-30 6:46 ` Jens Axboe
2007-09-30 12:07 ` Nick Piggin
2007-09-30 20:05 ` Jens Axboe
2007-09-30 20:12 ` Nick Piggin
2007-09-29 13:08 ` Nick Piggin
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