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From: Zhenzhong Duan <zhenzhong.duan@oracle.com>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	longman@redhat.com, SRINIVAS <srinivas.eeda@oracle.com>
Subject: Question about qspinlock nest
Date: Thu, 10 Jan 2019 16:02:53 +0800	[thread overview]
Message-ID: <e784a592-5dec-b0b3-6c70-d9ef775621d5@oracle.com> (raw)

Hi Maintainer,


There is a question confused me for days. Appreciate an answer.

In below code, the comment says we never have more than 4 nested contexts.

What happen if debug and mce exceptions nest with the four, or we ensure 
it never happen?


/*
  * Per-CPU queue node structures; we can never have more than 4 nested
  * contexts: task, softirq, hardirq, nmi.
  *
  * Exactly fits one 64-byte cacheline on a 64-bit architecture.
  *
  * PV doubles the storage and uses the second cacheline for PV state.
  */
static DEFINE_PER_CPU_ALIGNED(struct qnode, qnodes[MAX_NODES]);

-- 
Thanks
Zhenzhong


             reply	other threads:[~2019-01-10  8:03 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10  8:02 Zhenzhong Duan [this message]
2019-01-10 14:43 ` Question about qspinlock nest Waiman Long
2019-01-10 18:25   ` James Morse
2019-01-10 19:23     ` Waiman Long
2019-01-10 20:12     ` Peter Zijlstra
2019-01-11 18:32       ` James Morse
2019-01-14 13:16         ` Peter Zijlstra
2019-01-14 13:54           ` James Morse
2019-01-14 21:07             ` Waiman Long
2019-01-18 10:02             ` Peter Zijlstra
2019-01-18 10:24               ` Borislav Petkov
2019-01-18 14:50               ` Waiman Long
2019-01-18 20:06                 ` Peter Zijlstra
2019-01-18 21:30                   ` Waiman Long
     [not found]   ` <2eca6f60-3e8b-a389-27cb-8adbd9676607@oracle.com>
2019-01-11  9:16     ` Peter Zijlstra
2019-01-11 17:36       ` Borislav Petkov
2019-01-11 16:59     ` Waiman Long
2019-01-10 20:03 ` Peter Zijlstra
2019-01-14  9:25 Zhenzhong Duan

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