From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
Roman Pen <roman.penyaev@profitbricks.com>,
Andy Lutomirski <luto@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Tejun Heo <tj@kernel.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] x86/dumpstack: on oops do not rewind stack for kthread
Date: Fri, 21 Oct 2016 10:05:08 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1610210922490.4797@nanos> (raw)
In-Reply-To: <20161021055630.GA3102@twins.programming.kicks-ass.net>
On Fri, 21 Oct 2016, Peter Zijlstra wrote:
> We need to preserve the entire struct kthread on the stack, kthread just
> abuses that pointer to stash an on-stack kthread descriptor. See
> kthread():
>
> current->vfork_done = &self.exited;
>
> Its a horrible horrible thing kthread does. I suppose there might have
> been some intent by keeping that exited completion last in the
> structure, but *shudder*.
>
> But yes, leaving enough stack to not clobber that might keep this horror
> show working.
>
> ISTR talk about alternative schemes for this a long time ago, but I
> cannot recall :-(
The simplest solution would be to stick struct kthread into task_struct,
but that's bloat.
But we can allocate it seperately along with kthread_create_info. That's
pretty straight forward.
Thanks,
tglx
prev parent reply other threads:[~2016-10-21 8:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 15:43 Roman Pen
2016-09-21 15:43 ` [PATCH 2/2] sched: do not call workqueue sleep hook if task is already dead Roman Pen
2016-10-20 23:08 ` Andy Lutomirski
2016-10-21 15:47 ` Oleg Nesterov
2016-10-24 16:01 ` Roman Penyaev
2016-10-21 5:39 ` Peter Zijlstra
2016-10-20 23:07 ` [PATCH 1/2] x86/dumpstack: on oops do not rewind stack for kthread Andy Lutomirski
2016-10-21 5:56 ` Peter Zijlstra
2016-10-21 8:05 ` Thomas Gleixner [this message]
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