linux-kernel - Re: [PATCH 4.4 48/76] libceph: force GFP

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: <20170330135934.GH1972@dhcp22.suse.cz>
Date:   Thu, 30 Mar 2017 15:59:34 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Ilya Dryomov <idryomov@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org, Sergey Jerusalimov <wintchester@...il.com>,
        Jeff Layton <jlayton@...hat.com>, linux-xfs@...r.kernel.org
Subject: Re: [PATCH 4.4 48/76] libceph: force GFP_NOIO for socket allocations

On Thu 30-03-17 15:53:35, Ilya Dryomov wrote:
> On Thu, Mar 30, 2017 at 8:25 AM, Michal Hocko <mhocko@...nel.org> wrote:
> > On Wed 29-03-17 16:25:18, Ilya Dryomov wrote:
[...]
> >> are you saying it's OK for a block
> >> device to recurse back into the filesystem when doing I/O, potentially
> >> generating more I/O?
> >
> > No, block device has to make a forward progress guarantee when
> > allocating and so use mempools or other means to achieve the same.
> 
> OK, let me put this differently.  Do you agree that a block device
> cannot make _any_ kind of progress guarantee if it does a GFP_KERNEL
> allocation in the I/O path?

yes that is correct. And the same is correct for GFP_NOIO allocations as
well.
-- 
Michal Hocko
SUSE Labs