linux-kernel - Re: [PATCH v2 00/10] evacuate struct page from the block layer, introduce __pfn

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150508092044.GH889@ZenIV.linux.org.uk>
Date:	Fri, 8 May 2015 10:20:44 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Jerome Glisse <j.glisse@...il.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Boaz Harrosh <boaz@...xistor.com>, Jan Kara <jack@...e.cz>,
	Mike Snitzer <snitzer@...hat.com>, Neil Brown <neilb@...e.de>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Chris Mason <clm@...com>, Paul Mackerras <paulus@...ba.org>,
	"H. Peter Anvin" <hpa@...or.com>, Christoph Hellwig <hch@....de>,
	Alasdair Kergon <agk@...hat.com>,
	"linux-nvdimm@...ts.01.org" <linux-nvdimm@...1.01.org>,
	Mel Gorman <mgorman@...e.de>,
	Matthew Wilcox <willy@...ux.intel.com>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>,
	Rik van Riel <riel@...hat.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Jens Axboe <axboe@...nel.dk>, Theodore Ts'o <tytso@....edu>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Julia Lawall <Julia.Lawall@...6.fr>, Tejun Heo <tj@...nel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	paulmck@...ux.vnet.ibm.com
Subject: Re: [PATCH v2 00/10] evacuate struct page from the block layer,
 introduce __pfn_t

On Fri, May 08, 2015 at 07:37:59AM +0200, Ingo Molnar wrote:

>     same as iov_iter_get_pages(), except that pages array is allocated
>     (kmalloc if possible, vmalloc if that fails) and left for caller to
>     free.  Lustre and NFS ->direct_IO() switched to it.
>     
>     Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> 
> So if code does iov_iter_get_pages_alloc() on a user address that has 
> a real struct page behind it - and some other code does a regular 
> get_user_pages() on it, we'll have two sets of struct page 
> descriptors, the 'real' one, and a fake allocated one, right?

Huh?  iov_iter_get_pages() is given an array of pointers to struct page,
which it fills with what it finds.  iov_iter_get_pages_alloc() *allocates*
such an array, fills that with what it finds and gives the allocated array
to caller.

We are not allocating any struct page instances in either of those.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/