linux-kernel - Re: [PATCH v2] mm/page_isolation: fix a deadlock with printk()

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:   Thu, 10 Oct 2019 05:01:44 -0400
From:   Qian Cai <cai@....pw>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Petr Mladek <pmladek@...e.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        sergey.senozhatsky.work@...il.com, rostedt@...dmis.org,
        peterz@...radead.org, linux-mm@...ck.org,
        john.ogness@...utronix.de, akpm@...ux-foundation.org,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>, david@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/page_isolation: fix a deadlock with printk()



> On Oct 9, 2019, at 12:23 PM, Michal Hocko <mhocko@...nel.org> wrote:
> 
> If this was only about the memory offline code then I would agree. But
> we are talking about any printk from the zone->lock context and that is
> a bigger deal. Besides that it is quite natural that the printk code
> should be more universal and allow to be also called from the MM
> contexts as much as possible. If there is any really strong reason this
> is not possible then it should be documented at least.

Where is the best place to document this? I am thinking about under the “struct zone” definition’s lock field in mmzone.h.

Does workaround this potential deadlock and fix a few lockdep false positives for free count as a really strong reason?