linux-kernel - Re: Linux 3.11-rc4

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Message-ID: <20130805184625.GA11633@redhat.com>
Date:	Mon, 5 Aug 2013 20:46:25 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Felipe Contreras <felipe.contreras@...il.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Linux 3.11-rc4

On 08/04, Felipe Contreras wrote:
>
> I found a regression while running all v3.11-rcX kernels; Starcract II
> through wine crashes. The culprit is fab840f (ptrace: PTRACE_DETACH
> should do flush_ptrace_hw_breakpoint(child)), I revert that commit and
> there's no crash.

Heh. I pulled wine-git.

set_thread_context() does a lot of PTRACE_POKEUSER requests and then
it calls resume_after_ptrace() which simply does PTRACE_DETACH.

I'll recheck tomorrow, but it really looks as if it _wants_ to leak
the debug registers after detach. And more, it does PTRACE_ATTACH
only to set these regs.

And this is exactly what fab840f tries to prevent.

Oleg.

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