On Fri, Jan 17, 2014 at 12:08 PM, Waiman Long <waiman.l...@hp.com> wrote: > On 01/17/2014 02:17 PM, Andy Lutomirski wrote: >> >> On Fri, Jan 17, 2014 at 10:10 AM, Waiman Long<waiman.l...@hp.com> wrote: >>> >>> On 01/16/2014 08:39 AM, tip-bot for Peter Zijlstra wrote: >>>> >>>> Commit-ID: c026b3591e4f2a4993df773183704bb31634e0bd >>>> Gitweb: >>>> http://git.kernel.org/tip/c026b3591e4f2a4993df773183704bb31634e0bd >>>> Author: Peter Zijlstra<pet...@infradead.org> >>>> AuthorDate: Fri, 10 Jan 2014 21:06:03 +0100 >>>> Committer: Ingo Molnar<mi...@kernel.org> >>>> CommitDate: Thu, 16 Jan 2014 09:19:48 +0100 >>>> >>>> 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.l...@hp.com> >>>> Fixes: e00b12e64be9 ("perf/x86: Further optimize copy_from_user_nmi()") >>>> Cc: Aswin Chandramouleeswaran<as...@hp.com> >>>> Cc: Scott J Norton<scott.nor...@hp.com> >>>> Cc: Linus Torvalds<torva...@linux-foundation.org> >>>> Cc: Andy Lutomirski<l...@amacapital.net> >>>> Cc: Arnaldo Carvalho de Melo<a...@ghostprotocols.net> >>>> Cc: Andrew Morton<a...@linux-foundation.org> >>>> Signed-off-by: Peter Zijlstra<pet...@infradead.org> >>>> Link: >>>> >>>> http://lkml.kernel.org/r/20140110200603.gj7...@laptop.programming.kicks-ass.net >>>> Signed-off-by: Ingo Molnar<mi...@kernel.org> >>>> --- >>>> arch/x86/mm/fault.c | 18 ++++++++++++++++++ >>>> 1 file changed, 18 insertions(+) >>>> >>>> >>> Will that be picked up by Linus as it is a 3.13 regression? >> >> Does anyone actually know why this regressed recently? The buggy code >> has been there for quite a while. >> >> --Andy > > > Yes, the bug was there for a while, but a recent change by Peter (see the > "Fixes:" line above) made it much easier to hit it.
Thanks! So I feel slightly better now -- this particular bug didn't actually exist when I wrote the offending code :) But that also means that this should really be fixed in 3.13. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
