linux-kernel - Re: possible deadlock in sk_clone

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: <YECvT4QOitK954Ne@dhcp22.suse.cz>
Date:   Thu, 4 Mar 2021 10:58:39 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        syzbot <syzbot+506c8a2a115201881d45@...kaller.appspotmail.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux MM <linux-mm@...ck.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Mina Almasry <almasrymina@...gle.com>, tglx@...utronix.de,
        john.ogness@...utronix.de, urezki@...il.com, ast@...com
Subject: Re: possible deadlock in sk_clone_lock

On Wed 03-03-21 09:59:45, Paul E. McKenney wrote:
> On Wed, Mar 03, 2021 at 09:03:27AM +0100, Michal Hocko wrote:
[...]
> > Paul what is the current plan with in_atomic to be usable for !PREEMPT
> > configurations?
> 
> Ah, thank you for the reminder!  I have rebased that series on top of
> v5.12-rc1 on -rcu branch tglx-pc.2021.03.03a.
> 
> The current state is that Linus is not convinced that this change is
> worthwhile given that only RCU and printk() want it.  (BPF would use
> it if it were available, but is willing to live without it, at least in
> the short term.)
> 
> But maybe Linus will be convinced given your additional use case.
> Here is hoping!

Yes, hugetlb freeing path would benefit from this. You can reference
this lockdep report (http://lkml.kernel.org/r/000000000000f1c03b05bc43aadc@google.com)
with an additional argument that making hugetlb_lock irq safe is a
larger undertaking and we will need something reasonably backportable
for older kernels as well.
-- 
Michal Hocko
SUSE Labs