From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Jim Keniston <jkenisto@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux-mm <linux-mm@kvack.org>, Andi Kleen <andi@firstfloor.org>,
Christoph Hellwig <hch@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Thomas Gleixner <tglx@linutronix.de>,
Anton Arapov <anton@redhat.com>
Subject: Re: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id
Date: Mon, 16 Apr 2012 01:44:01 +0200 [thread overview]
Message-ID: <20120415234401.GA32662@redhat.com> (raw)
In-Reply-To: <1334526513.28150.23.camel@twins>
I'll write another email tomorrow, just one note...
On 04/15, Peter Zijlstra wrote:
>
> OK, still not seeing how your proposal could work.. consider the below
> patch comment, I'm not seeing how is_swbp_at_addr_fast() deals with an
> in-progress INT3 while we remove the probe.
>
> By ensuring the non-race with reg/unreg it will either find the uprobe
> (no problem)
Yes,
> or not find it and not see a breakpoint instruction either,
> even though the pending breakpoint was generated by a uprobe (which is
> now gone),
Yes,
> causing a false positive SIGTRAP.
No. Please note that if is_swbp_at_addr_fast() sets is_swbp == 0 we
restart this insn.
(note that we also restart if get_user_pages() fails, this is hopefully
is more correct too but minor).
> Or am I still not getting it?
My experience shows this is very unlikely. I am starting to think
I missed something, will re-check.
And. I have another reason for down_write() in register/unregister.
I am still not sure this is possible (I had no time to try to
implement), but it seems to me we can kill the uprobe counter in
mm_struct.
Oleg.
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next prev parent reply other threads:[~2012-04-15 23:44 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-05 22:20 [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id Oleg Nesterov
2012-04-05 22:20 ` [PATCH 1/6] uprobes: introduce find_active_uprobe() Oleg Nesterov
2012-04-05 22:21 ` [PATCH 2/6] uprobes: introduce is_swbp_at_addr_fast() Oleg Nesterov
2012-04-16 10:08 ` Peter Zijlstra
2012-04-16 14:44 ` Oleg Nesterov
2012-04-16 14:55 ` Peter Zijlstra
2012-04-16 15:34 ` Oleg Nesterov
2012-04-17 10:08 ` Peter Zijlstra
2012-04-17 17:09 ` Oleg Nesterov
2012-04-17 19:53 ` Peter Zijlstra
2012-04-05 22:21 ` [PATCH 3/6] uprobes: teach find_active_uprobe() to provide the "is_swbp" info Oleg Nesterov
2012-04-05 22:21 ` [PATCH 4/6] uprobes: change register_for_each_vma() to take mm->mmap_sem for writing Oleg Nesterov
2012-04-05 22:22 ` [PATCH 5/6] uprobes: teach handle_swbp() to rely on "is_swbp" rather than uprobes_srcu Oleg Nesterov
2012-04-05 22:22 ` [PATCH 6/6] uprobes: kill uprobes_srcu/uprobe_srcu_id Oleg Nesterov
2012-04-14 11:16 ` [RFC 0/6] " Ingo Molnar
2012-04-16 11:31 ` Srikar Dronamraju
2012-04-16 14:41 ` Oleg Nesterov
2012-04-25 12:52 ` Srikar Dronamraju
2012-04-25 14:22 ` Oleg Nesterov
2012-04-14 13:16 ` Peter Zijlstra
2012-04-14 20:52 ` Oleg Nesterov
2012-04-15 10:51 ` Peter Zijlstra
2012-04-15 19:53 ` Oleg Nesterov
2012-04-15 21:48 ` Peter Zijlstra
2012-04-15 23:44 ` Oleg Nesterov [this message]
2012-04-16 10:16 ` Peter Zijlstra
2012-04-16 21:47 ` Oleg Nesterov
2012-04-20 10:14 ` Peter Zijlstra
2012-04-20 10:16 ` Srikar Dronamraju
2012-04-20 18:58 ` Oleg Nesterov
2012-04-20 18:37 ` Oleg Nesterov
2012-04-23 7:14 ` Peter Zijlstra
2012-04-23 7:24 ` Srikar Dronamraju
2012-04-23 7:40 ` Peter Zijlstra
2012-04-23 17:29 ` Oleg Nesterov
2012-04-23 19:18 ` Peter Zijlstra
2012-04-23 20:50 ` Oleg Nesterov
2012-04-23 21:25 ` Oleg Nesterov
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