From: Andi Kleen <ak@suse.de>
To: Jiri Kosina <jkosina@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Zdenek Kabelac <zdenek.kabelac@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: print_vma_addr possible deadlock (was Re: Jeste jeden bug)
Date: Wed, 13 Feb 2008 18:13:46 +0100 [thread overview]
Message-ID: <200802131813.47136.ak@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0802131757360.7699@twin.jikos.cz>
> > in commit 03252919 you introduced print_vma_addr(), but this funcion for
> > obvious reasons takes mmap_sem, so it is not safe to call it from atomic
> > context (i.e. do_trap(), for example), which is behavior your patch
> > introduced.
Ah yes -- this behaviour of int3 do_trap was always a source of bugs. I remember
fixing such things in this area several times (last time in the RT kernel), but
I keep forgetting it. Sorry.
The correct fix is to run the int3 and debug handlers on the process stack
when the fault originated from user space. Then they can run preemptive
and it's ok to schedule for the lock too.
I'll fix that tomorrow.
-Andi
next prev parent reply other threads:[~2008-02-13 17:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <c4e36d110802130841l591f20a4j32759821543b554c@mail.gmail.com>
2008-02-13 16:52 ` Jeste jeden bug Jiri Kosina
2008-02-13 16:58 ` print_vma_addr possible deadlock (was Re: Jeste jeden bug) Jiri Kosina
2008-02-13 17:13 ` Andi Kleen [this message]
2008-02-13 19:35 ` Ingo Molnar
2008-02-13 19:40 ` Jiri Kosina
2008-02-13 20:18 ` Zdenek Kabelac
2008-02-13 22:09 ` Andi Kleen
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