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From: David Hildenbrand <dahi@linux.vnet.ibm.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"mingo@kernel.org" <mingo@kernel.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	"paulus@samba.org" <paulus@samba.org>,
	"schwidefsky@de.ibm.com" <schwidefsky@de.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [RFC 0/2] Reenable might_sleep() checks for might_fault() when atomic
Date: Thu, 27 Nov 2014 16:45:55 +0100	[thread overview]
Message-ID: <20141127164555.4bcebfe8@thinkpad-w530> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D1C9FDD6A@AcuExch.aculab.com>

> From: David Hildenbrand
> ...
> > Although it might not be optimal, but keeping a separate counter for
> > pagefault_disable() as part of the preemption counter seems to be the only
> > doable thing right now. I am not sure if a completely separated counter is even
> > possible, increasing the size of thread_info.
> 
> What about adding (say) 0x10000 for the more restrictive test?
> 
> 	David
> 

You mean as part of the preempt counter?

The current layout (on my branch) is

 * PREEMPT_MASK:        0x000000ff
 * SOFTIRQ_MASK:        0x0000ff00
 * HARDIRQ_MASK:        0x000f0000
 *     NMI_MASK:        0x00100000
 * PREEMPT_ACTIVE:      0x00200000

I would have added
 * PAGEFAULT_MASK:      0x03C00000

So 4 bit == 16 levels (tbd)

By implementing scope checks in the debug case like done for the regular
preempt_count_inc() preempt_count_dec(), we could catch over/underflows.

Thanks,

David

  reply	other threads:[~2014-11-27 15:46 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-25 11:43 [RFC 0/2] Reenable might_sleep() checks for might_fault() when atomic David Hildenbrand
2014-11-25 11:43 ` [RFC 1/2] powerpc/fsl-pci: atomic get_user when pagefault_disabled David Hildenbrand
2015-01-30  5:15   ` [RFC,1/2] " Scott Wood
2015-01-30  7:58     ` David Hildenbrand
2014-11-25 11:43 ` [RFC 2/2] mm, sched: trigger might_sleep() in might_fault() when atomic David Hildenbrand
2014-11-26  7:02 ` [RFC 0/2] Reenable might_sleep() checks for " Michael S. Tsirkin
2014-11-26 10:05   ` David Hildenbrand
2014-11-26 15:17     ` Michael S. Tsirkin
2014-11-26 15:23       ` Michael S. Tsirkin
2014-11-26 15:32         ` David Hildenbrand
2014-11-26 15:47           ` Michael S. Tsirkin
2014-11-26 16:02             ` David Hildenbrand
2014-11-26 16:19               ` Michael S. Tsirkin
2014-11-26 16:30                 ` Christian Borntraeger
2014-11-26 16:50                   ` Michael S. Tsirkin
2014-11-26 16:07             ` Christian Borntraeger
2014-11-26 16:32               ` Michael S. Tsirkin
2014-11-26 16:51                 ` Christian Borntraeger
2014-11-26 17:04                   ` Michael S. Tsirkin
2014-11-26 17:21                     ` Michael S. Tsirkin
2014-11-27  7:09                     ` Heiko Carstens
2014-11-27  7:40                       ` Michael S. Tsirkin
2014-11-27  8:03                       ` David Hildenbrand
2014-11-27 12:04                         ` Heiko Carstens
2014-11-27 12:08                           ` David Hildenbrand
2014-11-27 15:07                           ` Thomas Gleixner
2014-11-27 15:19                             ` David Hildenbrand
2014-11-27 15:37                               ` David Laight
2014-11-27 15:45                                 ` David Hildenbrand [this message]
2014-11-27 16:27                                   ` David Laight
2014-11-27 16:49                                     ` David Hildenbrand
2014-11-27 21:52                               ` Thomas Gleixner
2014-11-28  7:34                                 ` David Hildenbrand
2014-11-26 15:30       ` Christian Borntraeger
2014-11-26 15:37         ` Michael S. Tsirkin
2014-11-26 16:02           ` Christian Borntraeger
2014-11-26 15:22     ` Michael S. Tsirkin
2014-11-27 17:10 ` [PATCH RFC " David Hildenbrand
2014-11-27 17:10   ` [PATCH RFC 1/2] preempt: track pagefault_disable() calls in the preempt counter David Hildenbrand
2014-11-27 17:10   ` [PATCH RFC 2/2] mm, sched: trigger might_sleep() in might_fault() when pagefaults are disabled David Hildenbrand
2014-11-27 17:24     ` Michael S. Tsirkin
2014-11-27 17:32       ` Michael S. Tsirkin
2014-11-27 18:08         ` David Hildenbrand
2014-11-27 18:27           ` Michael S. Tsirkin

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