linux-kernel - Re: Pagecache: find_or_create_page does not call a proper page allocator function

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]

Date:	Tue, 24 Apr 2007 13:53:48 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Christoph Lameter <clameter@....com>
Cc:	Hugh Dickins <hugh@...itas.com>, Nick Piggin <npiggin@...e.de>,
	linux-kernel@...r.kernel.org, pj@....com
Subject: Re: Pagecache: find_or_create_page does not call a proper page
 allocator function

On Tue, 24 Apr 2007 13:44:50 -0700 (PDT) Christoph Lameter <clameter@....com> wrote:

> On Tue, 24 Apr 2007, Andrew Morton wrote:
> 
> > > I would say that the filesystem is broke if it has such expectations 
> > > regardless of page migration.
> > 
> > Others disagree ;)
> > 
> > The filesystem has *told* the core kernel what its allocation constraints
> > are by setting up mapping_gfp_mask().  If the core kernel stops honouring
> > that request then it is core kernel which is broken.
> 
> Then I think we should disable page migration for allocations that do not 
> allow access to the policy zone. That would fix it.

Can't we use mapping_gfp_mask() when allocating the destination page?

It would be better to do so, really.  Who knows, mapping_gfp_mask() might
be extented in the future to say "I want GFP_NOIO" or something.  Or a
filesystem might specify GFP_KERNEL for regular pagecache pages or
whatever.

Generally, the interface is "address_space tells core kernel how to
allocate its pages", and to be nice we should honour that in all places
where we allocate a page for an address_space.

If we'd had any brains we would have implemented this function as an
address_space_operations callback, but we don't so we didn't.

-
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/