linux-kernel - Re: [PATCH v2 4/9] cgroup: rstat: add WARN_ON

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] [day] [month] [year] [list]

Message-ID: <CAJD7tkZF+rCNW4pctjOfAetoAQRq7-exV-j-nRc_xYMkMBGY_A@mail.gmail.com>
Date:   Mon, 3 Apr 2023 13:39:29 -0700
From:   Yosry Ahmed <yosryahmed@...gle.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Shakeel Butt <shakeelb@...gle.com>, Tejun Heo <tj@...nel.org>,
        Josef Bacik <josef@...icpanda.com>,
        Jens Axboe <axboe@...nel.dk>,
        Zefan Li <lizefan.x@...edance.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Muchun Song <muchun.song@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Koutný <mkoutny@...e.com>,
        Vasily Averin <vasily.averin@...ux.dev>,
        cgroups@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH v2 4/9] cgroup: rstat: add WARN_ON_ONCE() if flushing
 outside task context

On Mon, Apr 3, 2023 at 1:38 AM Michal Hocko <mhocko@...e.com> wrote:
>
> On Fri 31-03-23 12:03:47, Yosry Ahmed wrote:
> > On Fri, Mar 31, 2023 at 4:02 AM Michal Hocko <mhocko@...e.com> wrote:
> > >
> > > On Thu 30-03-23 01:53:38, Yosry Ahmed wrote:
> > > [...]
> > > > Maybe we can add a primitive like might_sleep() for this, just food for thought.
> > >
> > > I do not think it is the correct to abuse might_sleep if the function
> > > itself doesn't sleep. If it does might_sleep is already involved.
> >
> > Oh, sorry if I wasn't clear, I did not mean to reuse might_sleep() --
> > I meant introducing a new similar debug primitive that shouts if irqs
> > are disabled.
>
> This is circling back to original concerns about arbitrary decision to
> care about IRQs. Is this really any different from spin locks or preempt
> disabled critical sections preventing any scheduling and potentially
> triggereing soft lockups?

Not really, I am sure there are other code paths that may cause
similar problems. At least we can start annotating them so that we
don't regress them (e.g. by introducing a caller that disables irqs --
converting them into hard lockups).

> --
> Michal Hocko
> SUSE Labs