From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 10 Jan 2014 20:06:03 +0000 (+0100)
Subject: x86, mm, perf: Allow recursive faults from interrupts
X-Git-Tag: v3.13~3^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c026b3591e4f2a4993df773183704bb31634e0bd;p=pandora-kernel.git

x86, mm, perf: Allow recursive faults from interrupts

Waiman managed to trigger a PMI while in a emulate_vsyscall() fault,
the PMI in turn managed to trigger a fault while obtaining a stack
trace. This triggered the sig_on_uaccess_error recursive fault logic
and killed the process dead.

Fix this by explicitly excluding interrupts from the recursive fault
logic.

Reported-and-Tested-by: Waiman Long <waiman.long@hp.com>
Fixes: e00b12e64be9 ("perf/x86: Further optimize copy_from_user_nmi()")
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140110200603.GJ7572@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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