From: Christoph Hellwig <hch@infradead.org>
To: Dave Jones <davej@codemonkey.org.uk>,
Christoph Hellwig <hch@infradead.org>,
Kees Cook <keescook@chromium.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: sg_io HARDENED_USERCOPY_PAGESPAN trace
Date: Fri, 30 Dec 2016 07:10:49 -0800 [thread overview]
Message-ID: <20161230151049.GA20387@infradead.org> (raw)
In-Reply-To: <20161230150139.ulljsnnqntzku7tq@codemonkey.org.uk>
On Fri, Dec 30, 2016 at 10:01:39AM -0500, Dave Jones wrote:
> I threw this debug printk into the pagespan code to see what exactly
> it was complaining about..
>
> ptr:ffff88042614cff8 end:ffff88042614d003 n:c
>
> so it was copying 12 bytes that spanned two pages.
> >From my reading of the config option help text, this thing is
> complaining that wasn't allocated with __GFP_COMP maybe ?
If this is on a devie using blk-mq the block core will use high
order allocations (as high as possible) to allocate the requests
for each queue, so struct request could very well span multiple
pages. But I don't see what __GFP_COMP would have to do with
user copy annoations. As all requests for a queue are freed
togeth again there is no point in setting __GFP_COMP for the
request allocations.
next prev parent reply other threads:[~2016-12-30 15:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-28 21:40 sg_io HARDENED_USERCOPY_PAGESPAN trace Dave Jones
2016-12-29 7:56 ` Christoph Hellwig
2016-12-29 15:43 ` Dave Jones
2016-12-30 13:37 ` Christoph Hellwig
2016-12-30 15:01 ` Dave Jones
2016-12-30 15:10 ` Christoph Hellwig [this message]
2017-01-03 21:48 ` Kees Cook
2017-01-08 9:44 ` Christoph Hellwig
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