From: Sasha Levin <sasha.levin@oracle.com>
To: Andy Lutomirski <luto@amacapital.net>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
"Peter Zijlstra" <peterz@infradead.org>,
"Oleg Nesterov" <oleg@redhat.com>,
"Tony Luck" <tony.luck@intel.com>,
"Andi Kleen" <andi@firstfloor.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"Josh Triplett" <josh@joshtriplett.org>,
"Frédéric Weisbecker" <fweisbec@gmail.com>
Subject: Re: [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context
Date: Thu, 22 Jan 2015 16:52:57 -0500 [thread overview]
Message-ID: <54C17139.1040706@oracle.com> (raw)
In-Reply-To: <7665538633a500255d7da9ca5985547f6a2aa191.1416604491.git.luto@amacapital.net>
On 11/21/2014 04:26 PM, Andy Lutomirski wrote:
> We currently pretend that IST context is like standard exception
> context, but this is incorrect. IST entries from userspace are like
> standard exceptions except that they use per-cpu stacks, so they are
> atomic. IST entries from kernel space are like NMIs from RCU's
> perspective -- they are not quiescent states even if they
> interrupted the kernel during a quiescent state.
>
> Add and use ist_enter and ist_exit to track IST context. Even
> though x86_32 has no IST stacks, we track these interrupts the same
> way.
>
> This fixes two issues:
>
> - Scheduling from an IST interrupt handler will now warn. It would
> previously appear to work as long as we got lucky and nothing
> overwrote the stack frame. (I don't know of any bugs in this
> that would trigger the warning, but it's good to be on the safe
> side.)
>
> - RCU handling in IST context was dangerous. As far as I know,
> only machine checks were likely to trigger this, but it's good to
> be on the safe side.
>
> Note that the machine check handlers appears to have been missing
> any context tracking at all before this patch.
Hi Andy, Paul,
I *suspect* that the following is a result of this commit:
[ 543.999079] ===============================
[ 543.999079] [ INFO: suspicious RCU usage. ]
[ 543.999079] 3.19.0-rc5-next-20150121-sasha-00064-g3c37e35-dirty #1809 Not tainted
[ 543.999079] -------------------------------
[ 543.999079] include/linux/rcupdate.h:892 rcu_read_lock() used illegally while idle!
[ 543.999079]
[ 543.999079] other info that might help us debug this:
[ 543.999079]
[ 543.999079]
[ 543.999079] RCU used illegally from idle CPU!
[ 543.999079] rcu_scheduler_active = 1, debug_locks = 1
[ 543.999079] RCU used illegally from extended quiescent state!
[ 543.999079] 1 lock held by trinity-main/15058:
[ 543.999079] #0: (rcu_read_lock){......}, at: atomic_notifier_call_chain (kernel/notifier.c:192)
[ 543.999079]
[ 543.999079] stack backtrace:
[ 543.999079] CPU: 16 PID: 15058 Comm: trinity-main Not tainted 3.19.0-rc5-next-20150121-sasha-00064-g3c37e35-dirty #1809
[ 543.999079] 0000000000000000 0000000000000000 0000000000000001 ffff8801af907d88
[ 543.999079] ffffffff92e9e917 0000000000000011 ffff8801afcf8000 ffff8801af907db8
[ 543.999079] ffffffff815f5613 ffffffff9654d4a0 0000000000000003 ffff8801af907e28
[ 543.999079] Call Trace:
[ 543.999079] dump_stack (lib/dump_stack.c:52)
[ 543.999079] lockdep_rcu_suspicious (kernel/locking/lockdep.c:4259)
[ 543.999079] atomic_notifier_call_chain (include/linux/rcupdate.h:892 kernel/notifier.c:182 kernel/notifier.c:193)
[ 543.999079] ? atomic_notifier_call_chain (kernel/notifier.c:192)
[ 543.999079] notify_die (kernel/notifier.c:538)
[ 543.999079] ? atomic_notifier_call_chain (kernel/notifier.c:538)
[ 543.999079] ? debug_smp_processor_id (lib/smp_processor_id.c:57)
[ 543.999079] do_debug (arch/x86/kernel/traps.c:652)
[ 543.999079] ? trace_hardirqs_on (kernel/locking/lockdep.c:2609)
[ 543.999079] ? do_int3 (arch/x86/kernel/traps.c:610)
[ 543.999079] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2554 kernel/locking/lockdep.c:2601)
[ 543.999079] debug (arch/x86/kernel/entry_64.S:1310)
Thanks,
Sasha
next prev parent reply other threads:[~2015-01-22 21:54 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-21 21:26 [PATCH v4 0/5] x86: Rework IST interrupts Andy Lutomirski
2014-11-21 21:26 ` [PATCH v4 1/5] uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME Andy Lutomirski
2014-11-22 16:55 ` Borislav Petkov
2014-11-24 17:58 ` Andy Lutomirski
2014-11-21 21:26 ` [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context Andy Lutomirski
2014-11-21 21:32 ` Andy Lutomirski
2014-11-21 22:07 ` Paul E. McKenney
2014-11-21 22:19 ` Andy Lutomirski
2014-11-21 22:55 ` Paul E. McKenney
2014-11-21 23:06 ` Andy Lutomirski
2014-11-21 23:38 ` Paul E. McKenney
2014-11-22 2:00 ` Andy Lutomirski
2014-11-22 4:20 ` Paul E. McKenney
2014-11-22 5:53 ` Andy Lutomirski
2014-11-22 23:41 ` Paul E. McKenney
2014-11-24 20:22 ` Andy Lutomirski
2014-11-24 20:54 ` Paul E. McKenney
2014-11-24 21:02 ` Andy Lutomirski
2014-11-24 21:35 ` Paul E. McKenney
2014-11-24 22:34 ` Paul E. McKenney
2014-11-24 22:36 ` Andy Lutomirski
2014-11-24 22:57 ` Paul E. McKenney
2014-11-24 23:31 ` Paul E. McKenney
2014-11-24 23:35 ` Andy Lutomirski
2014-11-24 23:50 ` Paul E. McKenney
2014-11-24 23:52 ` Andy Lutomirski
2014-11-25 18:58 ` Borislav Petkov
2014-11-25 19:16 ` Paul E. McKenney
2014-12-11 0:22 ` Tony Luck
2014-12-11 0:24 ` Andy Lutomirski
2015-01-05 21:46 ` Tony Luck
2015-01-05 21:54 ` Andy Lutomirski
2015-01-06 0:44 ` [PATCH] x86, mce: Get rid of TIF_MCE_NOTIFY and associated mce tricks Luck, Tony
2015-01-06 1:01 ` Andy Lutomirski
2015-01-06 18:00 ` Luck, Tony
2015-01-07 12:13 ` Borislav Petkov
2015-01-07 15:51 ` Andy Lutomirski
2015-01-07 15:58 ` Borislav Petkov
2015-01-07 16:12 ` Paul E. McKenney
2014-11-25 17:13 ` [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context Paul E. McKenney
2014-11-27 7:03 ` Lai Jiangshan
2014-11-27 16:46 ` Paul E. McKenney
2014-11-24 21:27 ` Paul E. McKenney
2014-11-21 22:20 ` Frederic Weisbecker
2014-11-21 22:00 ` Paul E. McKenney
2014-11-22 17:20 ` Borislav Petkov
2014-11-24 19:48 ` Andy Lutomirski
2015-01-22 21:52 ` Sasha Levin [this message]
2015-01-23 17:58 ` Andy Lutomirski
2015-01-23 18:04 ` Borislav Petkov
2015-01-23 18:34 ` Andy Lutomirski
2015-01-23 20:48 ` Sasha Levin
2015-01-24 1:25 ` Andy Lutomirski
2015-01-28 16:33 ` Andy Lutomirski
2015-01-28 17:48 ` Paul E. McKenney
2015-01-28 21:02 ` Andy Lutomirski
2015-01-30 19:57 ` Sasha Levin
2015-01-31 1:28 ` Sasha Levin
2015-01-31 3:12 ` Andy Lutomirski
2015-01-31 12:50 ` Andy Lutomirski
2015-01-31 13:01 ` [PATCH] x86, traps: Fix ist_enter from userspace Andy Lutomirski
2015-01-31 15:09 ` Sasha Levin
2015-01-31 16:18 ` Paul E. McKenney
2015-02-01 2:17 ` Andy Lutomirski
2015-02-04 6:01 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2014-11-21 21:26 ` [PATCH v4 3/5] x86, entry: Switch stacks on a paranoid entry " Andy Lutomirski
2014-11-24 15:55 ` Borislav Petkov
2014-11-21 21:26 ` [PATCH v4 4/5] x86: Clean up current_stack_pointer Andy Lutomirski
2014-11-24 11:39 ` Borislav Petkov
2014-11-21 21:26 ` [PATCH v4 5/5] x86, traps: Add ist_begin_non_atomic and ist_end_non_atomic Andy Lutomirski
2014-11-24 15:54 ` Borislav Petkov
2014-11-24 19:52 ` Andy Lutomirski
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