From: Petr Mladek <pmladek@suse.com>
To: Alexander Popov <alex.popov@linux.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Joerg Roedel <jroedel@suse.de>,
Maciej Rozycki <macro@orcam.me.uk>,
Muchun Song <songmuchun@bytedance.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Robin Murphy <robin.murphy@arm.com>,
Randy Dunlap <rdunlap@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Luis Chamberlain <mcgrof@kernel.org>, Wei Liu <wl@xen.org>,
John Ogness <john.ogness@linutronix.de>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Jann Horn <jannh@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mark Rutland <mark.rutland@arm.com>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will.deacon@arm.com>,
David S Miller <davem@davemloft.net>,
Borislav Petkov <bp@alien8.de>,
kernel-hardening@lists.openwall.com,
linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, notify@kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter
Date: Fri, 1 Oct 2021 14:23:48 +0200 [thread overview]
Message-ID: <20211001122348.GB965@pathway.suse.cz> (raw)
In-Reply-To: <a09c1d4d-1d5b-9092-ae3a-61bc22689dd2@linux.com>
On Thu 2021-09-30 18:05:54, Alexander Popov wrote:
> On 30.09.2021 12:15, Petr Mladek wrote:
> > On Wed 2021-09-29 12:49:24, Paul E. McKenney wrote:
> >> On Wed, Sep 29, 2021 at 10:01:33PM +0300, Alexander Popov wrote:
> >>> This patch was tested using CONFIG_LKDTM.
> >>> The kernel kills a process that performs this:
> >>> echo WARNING > /sys/kernel/debug/provoke-crash/DIRECT
> >>>
> >>> If you are fine with this approach, I will prepare a patch adding the
> >>> pkill_on_warn sysctl.
> >>
> >> I suspect that you need a list of kthreads for which you are better
> >> off just invoking panic(). RCU's various kthreads, for but one set
> >> of examples.
> >
> > I wonder if kernel could survive killing of any kthread. I have never
> > seen a code that would check whether a kthread was killed and
> > restart it.
>
> The do_group_exit() function calls do_exit() from kernel/exit.c, which is also
> called during a kernel oops. This function cares about a lot of special cases
> depending on the current task_struct. Is it fine?
IMHO, the bigger problem is that nobody will start the kthreads again.
As a result, some kernel functionality will not longer work.
User space threads are different. The user/admin typically
have a chance to start them again.
We might get inspiration in OOM killer. It never kills kthreads
and the init process, see oom_unkillable_task().
It would be better to panic() when WARN() is called from a kthread
or the init process.
Best Regards,
Petr
next prev parent reply other threads:[~2021-10-01 12:23 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 18:58 [PATCH] Introduce the pkill_on_warn boot parameter Alexander Popov
2021-09-29 19:01 ` Alexander Popov
2021-09-29 19:49 ` Paul E. McKenney
2021-09-30 9:15 ` Petr Mladek
2021-09-30 15:05 ` Alexander Popov
2021-10-01 12:23 ` Petr Mladek [this message]
2021-09-30 16:59 ` Steven Rostedt
2021-10-01 12:09 ` Petr Mladek
2021-09-30 18:28 ` Kees Cook
2021-10-01 19:59 ` Linus Torvalds
2021-10-02 11:41 ` Alexander Popov
2021-10-02 12:13 ` Steven Rostedt
2021-10-02 16:33 ` Alexander Popov
2021-10-02 16:52 ` Linus Torvalds
2021-10-02 21:05 ` Alexander Popov
2021-10-05 19:48 ` Eric W. Biederman
2021-10-06 14:56 ` Alexander Popov
2021-10-22 17:30 ` Alexander Popov
2022-07-27 16:17 ` Alexey Khoroshilov
2022-07-27 16:30 ` Jann Horn
2022-07-27 16:43 ` Alexey Khoroshilov
2022-07-27 16:42 ` Linus Torvalds
2022-07-27 17:47 ` Alexey Khoroshilov
2021-09-29 23:31 ` Andrew Morton
2021-09-30 18:27 ` Alexander Popov
2021-09-30 18:36 ` Kees Cook
2021-09-29 19:03 ` Dave Hansen
2021-09-29 19:47 ` Peter Zijlstra
2021-09-29 20:06 ` Kees Cook
2021-09-30 13:55 ` Alexander Popov
2021-09-30 18:20 ` Kees Cook
2021-10-02 18:04 ` Al Viro
2021-10-02 18:31 ` Steven Rostedt
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