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From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
To: Paul Burton <paul.burton@imgtec.com>
Cc: <linux-mips@linux-mips.org>, Lars Persson <lars.persson@axis.com>,
	"stable # v4 . 1+" <stable@vger.kernel.org>,
	"Steven J. Hill" <Steven.Hill@imgtec.com>,
	David Daney <david.daney@cavium.com>,
	Huacai Chen <chenhc@lemote.com>,
	Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>,
	<linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jerome Marchand <jmarchan@redhat.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [4/4] MIPS: Sync icache & dcache in set_pte_at
Date: Fri, 4 Mar 2016 17:06:04 -0800	[thread overview]
Message-ID: <56DA30FC.10603@imgtec.com> (raw)
In-Reply-To: <56D9F78E.6090303@imgtec.com>

On Sat, Mar 05, 2016 at 12:21:54AM +0000, Paul Burton wrote:

> > On Fri, Mar 04, 2016 at 07:02:24PM +0000, Lars Persson wrote:
> > > Hi
> > >
> > > Some further thoughts on the matter. You have so far not showed a
> > > valid example of a race condition. The two examples you give in the
> > > commit message are for a _single_ thread existing in the address space
> > > (fork and execve).
> >
> > Hi Lars,
> >
> > Neither fork nor exec are limited to a single thread existing in the
> > address space - I'm not sure what you're saying? fork by its very
> > definition results in 2.
>
> Ok, exec kinda is (it's late...). Still, fork clearly isn't.
Again - fork doesn't copy any user page. Copy_page_range just 
manipulates PTE tree.

So, no user page cache flushes are needed on MIPS during fork, at least now.

- Leonid.

WARNING: multiple messages have this Message-ID (diff)
From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
To: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org, Lars Persson <lars.persson@axis.com>,
	"stable # v4 . 1+" <stable@vger.kernel.org>,
	"Steven J. Hill" <Steven.Hill@imgtec.com>,
	David Daney <david.daney@cavium.com>,
	Huacai Chen <chenhc@lemote.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Jerome Marchand <jmarchan@redhat.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [4/4] MIPS: Sync icache & dcache in set_pte_at
Date: Fri, 4 Mar 2016 17:06:04 -0800	[thread overview]
Message-ID: <56DA30FC.10603@imgtec.com> (raw)
Message-ID: <20160305010604.Ao2Xm5WmW8er2Egdt1_5PBQTN4XB4CqIxPKzB5IEGiM@z> (raw)
In-Reply-To: <56D9F78E.6090303@imgtec.com>

On Sat, Mar 05, 2016 at 12:21:54AM +0000, Paul Burton wrote:

> > On Fri, Mar 04, 2016 at 07:02:24PM +0000, Lars Persson wrote:
> > > Hi
> > >
> > > Some further thoughts on the matter. You have so far not showed a
> > > valid example of a race condition. The two examples you give in the
> > > commit message are for a _single_ thread existing in the address space
> > > (fork and execve).
> >
> > Hi Lars,
> >
> > Neither fork nor exec are limited to a single thread existing in the
> > address space - I'm not sure what you're saying? fork by its very
> > definition results in 2.
>
> Ok, exec kinda is (it's late...). Still, fork clearly isn't.
Again - fork doesn't copy any user page. Copy_page_range just 
manipulates PTE tree.

So, no user page cache flushes are needed on MIPS during fork, at least now.

- Leonid.

  parent reply	other threads:[~2016-03-05  1:06 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-01  2:37 [PATCH 0/4] MIPS cache & highmem fixes Paul Burton
2016-03-01  2:37 ` Paul Burton
2016-03-01  2:37 ` [PATCH 1/4] MIPS: Flush dcache for flush_kernel_dcache_page Paul Burton
2016-03-01  2:37   ` Paul Burton
2016-03-04 15:09   ` Lars Persson
2016-03-29  8:29     ` Ralf Baechle
2016-03-01  2:37 ` [PATCH 2/4] MIPS: Flush highmem pages in __flush_dcache_page Paul Burton
2016-03-01  2:37   ` Paul Burton
2016-03-29  8:35   ` Ralf Baechle
2016-03-29  8:55     ` Paul Burton
2016-03-29  8:55       ` Paul Burton
2016-03-01  2:37 ` [PATCH 3/4] MIPS: Handle highmem pages in __update_cache Paul Burton
2016-03-01  2:37   ` Paul Burton
2016-03-29  8:39   ` Ralf Baechle
2016-03-01  2:37 ` [PATCH 4/4] MIPS: Sync icache & dcache in set_pte_at Paul Burton
2016-03-01  2:37   ` Paul Burton
2016-03-01  9:44   ` Lars Persson
2016-03-01  9:44     ` Lars Persson
2016-03-01 17:13   ` David Daney
2016-03-01 17:13     ` David Daney
2016-03-01 17:19     ` Paul Burton
2016-03-01 17:19       ` Paul Burton
2016-03-02 14:12       ` Ralf Baechle
2016-03-02 14:24         ` Paul Burton
2016-03-02 14:24           ` Paul Burton
2016-03-04 17:43       ` David Daney
2016-03-04 17:43         ` David Daney
2016-03-04 17:47         ` Paul Burton
2016-03-04 17:47           ` Paul Burton
2016-03-03  3:03   ` [4/4] " Leonid Yegoshin
2016-03-03  3:03     ` Leonid Yegoshin
2016-03-04 10:37     ` Paul Burton
2016-03-04 10:37       ` Paul Burton
2016-03-04 15:20       ` Lars Persson
2016-03-04 21:01       ` Leonid Yegoshin
2016-03-04 21:01         ` Leonid Yegoshin
2016-03-04 21:21         ` Leonid Yegoshin
2016-03-04 21:21           ` Leonid Yegoshin
2016-03-05  1:06         ` Leonid Yegoshin [this message]
2016-03-05  1:06           ` Leonid Yegoshin
2016-03-04 19:02   ` [PATCH 4/4] " Lars Persson
2016-03-05  0:21     ` Paul Burton
2016-03-05  0:27       ` Paul Burton
2016-03-02 11:39 ` [PATCH 0/4] MIPS cache & highmem fixes Harvey Hunt
2016-03-02 11:39   ` Harvey Hunt

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