linux-kernel - Re: [PATCH 2/2] hw_breakpoint: Use cpu_possible_mask in {reserve,release}_bp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130615124639.GA1965@somewhere.redhat.com>
Date:	Sat, 15 Jun 2013 14:46:41 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Vince Weaver <vincent.weaver@...ne.edu>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	trinity@...r.kernel.org, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH 2/2] hw_breakpoint: Use cpu_possible_mask in
 {reserve,release}_bp_slot()

On Sat, Jun 01, 2013 at 08:21:39PM +0200, Oleg Nesterov wrote:
> fetch_bp_busy_slots() and toggle_bp_slot() use for_each_online_cpu(),
> this is obviously wrong wrt cpu_up() or cpu_down(), we can over/under
> account the per-cpu numbers.
> 
> For example:
> 
> 	# echo 0 >> /sys/devices/system/cpu/cpu1/online
> 	# perf record -e mem:0x10 -p 1 &
> 	# echo 1 >> /sys/devices/system/cpu/cpu1/online
> 	# perf record -e mem:0x10,mem:0x10,mem:0x10,mem:0x10 -C1 -a &
> 	# taskset -p 0x2 1
> 
> triggers the same WARN_ONCE("Can't find any breakpoint slot") in
> arch_install_hw_breakpoint().
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> Cc: <stable@...r.kernel.org>

Acked-by: Frederic Weisbecker <fweisbec@...il.com>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/