From: Jens Axboe <jens.axboe@oracle.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: akpm@linux-foundation.org, max@duempel.org,
torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch 2/3] splice: implement default splice_read method
Date: Thu, 14 May 2009 20:00:03 +0200 [thread overview]
Message-ID: <20090514180003.GU4140@kernel.dk> (raw)
In-Reply-To: <E1M4f8b-0000Tb-GI@pomaz-ex.szeredi.hu>
On Thu, May 14 2009, Miklos Szeredi wrote:
> On Thu, 14 May 2009, Jens Axboe wrote:
>
> > > The bigger problem is that the default_file_splice_write()
> > > implementation in the other patch does the same (it calls
> > > buf->ops->map() on all buffers).
> >
> > Yep that's even worse, as that should go BUG() pretty much immediately
> > when the KM_USER0 slot is reused!
>
> No, ->map() calls plain kmap() if "atomic" argument is zero.
> Nevertheless the deadlock due to multiple kmaps is still possible.
It's buggy either way, didn't check whether you used atomic maps or not.
> > > Hmm. Simple solution would be to do a write() for each buffer. But
> > > this only affects HIGHMEM kernels, so it's a bit pointless to do that
> > > on all archs. Sigh...
> >
> > It is unfortunate, we are going to be stuck with that for some time
> > still...
>
> I'm going to be offline till next monday, I'll post a fix after that.
Until monday, or the monday after? I'm tempted to revert the
readv/writev part until this is settled, we cannot ship it as-is.
--
Jens Axboe
next prev parent reply other threads:[~2009-05-14 18:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-07 13:37 [patch 0/3] make splice more generic Miklos Szeredi
2009-05-07 13:37 ` [patch 1/3] splice: implement pipe to pipe splicing Miklos Szeredi
2009-05-07 13:37 ` [patch 2/3] splice: implement default splice_read method Miklos Szeredi
2009-05-13 5:35 ` Andrew Morton
2009-05-13 6:37 ` Jens Axboe
2009-05-13 9:01 ` Miklos Szeredi
2009-05-14 17:29 ` Jens Axboe
2009-05-14 17:54 ` Miklos Szeredi
2009-05-14 18:00 ` Jens Axboe [this message]
2009-05-18 12:36 ` Miklos Szeredi
2009-05-19 9:38 ` Jens Axboe
2009-05-07 13:37 ` [patch 3/3] splice: implement default splice_write method Miklos Szeredi
2009-05-07 15:55 ` [patch 0/3] make splice more generic Linus Torvalds
2009-05-11 15:17 ` Miklos Szeredi
2009-05-09 11:36 ` Max Kellermann
2009-05-11 12:12 ` Jens Axboe
2009-05-11 15:22 ` Miklos Szeredi
2009-05-14 20:27 ` Jamie Lokier
2009-05-15 7:32 ` Jens Axboe
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