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From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
	Andi Kleen <ak@linux.intel.com>,
	Matthew Wilcox <matthew.r.wilcox@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Dave Chinner <david@fromorbit.com>, Ning Qu <quning@gmail.com>,
	linux-mm <linux-mm@kvack.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv3 0/2] mm: map few pages around fault address if they are in page cache
Date: Fri, 28 Feb 2014 17:08:22 -0600	[thread overview]
Message-ID: <CA+55aFyuspw4viBYbjd=j+zOHe1w-_LMCUHdyTjt4yUqUyosdw@mail.gmail.com> (raw)
In-Reply-To: <20140228001039.GB8034@node.dhcp.inet.fi>

On Thu, Feb 27, 2014 at 6:10 PM, Kirill A. Shutemov
<kirill@shutemov.name> wrote:
>
> Also Matthew noticed that some drivers do ugly hacks like fault in whole
> VMA on first page fault. IIUC, it's for performance reasons. See
> psbfb_vm_fault() or ttm_bo_vm_fault().

I guarantee it's not for performance reasons, it's probably some other breakage.

And if anything really does want to populate things fully, doing so at
fault time is wrong anyway, you should just use MAP_POPULATE at mmap
time.

So I'll believe the shm/tmpfs issue, and that's "mm internal" anyway.
But random crappy drivers? No way in hell.

               Linus

WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
	Andi Kleen <ak@linux.intel.com>,
	Matthew Wilcox <matthew.r.wilcox@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Dave Chinner <david@fromorbit.com>, Ning Qu <quning@gmail.com>,
	linux-mm <linux-mm@kvack.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv3 0/2] mm: map few pages around fault address if they are in page cache
Date: Fri, 28 Feb 2014 17:08:22 -0600	[thread overview]
Message-ID: <CA+55aFyuspw4viBYbjd=j+zOHe1w-_LMCUHdyTjt4yUqUyosdw@mail.gmail.com> (raw)
In-Reply-To: <20140228001039.GB8034@node.dhcp.inet.fi>

On Thu, Feb 27, 2014 at 6:10 PM, Kirill A. Shutemov
<kirill@shutemov.name> wrote:
>
> Also Matthew noticed that some drivers do ugly hacks like fault in whole
> VMA on first page fault. IIUC, it's for performance reasons. See
> psbfb_vm_fault() or ttm_bo_vm_fault().

I guarantee it's not for performance reasons, it's probably some other breakage.

And if anything really does want to populate things fully, doing so at
fault time is wrong anyway, you should just use MAP_POPULATE at mmap
time.

So I'll believe the shm/tmpfs issue, and that's "mm internal" anyway.
But random crappy drivers? No way in hell.

               Linus

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  parent reply	other threads:[~2014-02-28 23:08 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-27 19:53 [PATCHv3 0/2] mm: map few pages around fault address if they are in page cache Kirill A. Shutemov
2014-02-27 19:53 ` Kirill A. Shutemov
2014-02-27 19:53 ` [PATCHv3 1/2] mm: introduce vm_ops->map_pages() Kirill A. Shutemov
2014-02-27 19:53   ` Kirill A. Shutemov
2014-02-27 21:59   ` Dave Hansen
2014-02-27 21:59     ` Dave Hansen
2014-02-27 22:06     ` Linus Torvalds
2014-02-27 22:06       ` Linus Torvalds
2014-02-27 22:34       ` Dave Hansen
2014-02-27 22:34         ` Dave Hansen
2014-02-28  0:18         ` Kirill A. Shutemov
2014-02-28  0:18           ` Kirill A. Shutemov
2014-02-28 11:50         ` Benjamin Herrenschmidt
2014-02-28 11:50           ` Benjamin Herrenschmidt
2014-02-27 22:08     ` Andrew Morton
2014-02-27 22:08       ` Andrew Morton
2014-03-03 23:16   ` Andrew Morton
2014-03-04  1:26     ` Kirill A. Shutemov
2014-03-04  1:26       ` Kirill A. Shutemov
2014-03-04  1:26       ` Kirill A. Shutemov
2014-03-05  0:04     ` Rusty Russell
2014-03-05  0:04       ` Rusty Russell
2014-03-05 20:02       ` Andrew Morton
2014-03-05 20:02         ` Andrew Morton
2014-07-24  3:33   ` Sasha Levin
2014-07-24  3:33     ` Sasha Levin
2014-07-24  6:53     ` Andrey Ryabinin
2014-07-24  6:53       ` Andrey Ryabinin
2014-07-24 12:48       ` Sasha Levin
2014-07-24 12:48         ` Sasha Levin
2014-07-24 13:05     ` Sasha Levin
2014-07-24 13:05       ` Sasha Levin
2014-07-24 13:30       ` Konstantin Khlebnikov
2014-07-24 13:30         ` Konstantin Khlebnikov
2014-07-28  7:43     ` [PATCH] mm: don't allow fault_around_bytes to be 0 Andrey Ryabinin
2014-07-28  7:43       ` Andrey Ryabinin
2014-07-28  7:47       ` Andrey Ryabinin
2014-07-28  7:47         ` Andrey Ryabinin
2014-07-28  9:36       ` Kirill A. Shutemov
2014-07-28  9:36         ` Kirill A. Shutemov
2014-07-28  9:36         ` Kirill A. Shutemov
2014-07-28 10:27         ` Andrey Ryabinin
2014-07-28 10:27           ` Andrey Ryabinin
2014-07-28 10:27           ` Andrey Ryabinin
2014-07-28 10:27           ` Andrey Ryabinin
2014-07-28 10:52           ` Kirill A. Shutemov
2014-07-28 10:52             ` Kirill A. Shutemov
2014-07-28 12:32           ` Sasha Levin
2014-07-28 12:32             ` Sasha Levin
2014-07-28 22:43           ` David Rientjes
2014-07-28 22:43             ` David Rientjes
2014-07-28 15:26         ` Dave Hansen
2014-07-28 15:26           ` Dave Hansen
2014-02-27 19:53 ` [PATCHv3 2/2] mm: implement ->map_pages for page cache Kirill A. Shutemov
2014-02-27 19:53   ` Kirill A. Shutemov
2014-02-27 21:47   ` Andrew Morton
2014-02-27 21:47     ` Andrew Morton
2014-02-28  0:31     ` Kirill A. Shutemov
2014-02-28  0:31       ` Kirill A. Shutemov
2014-04-02 18:03   ` Konstantin Khlebnikov
2014-04-02 18:03     ` Konstantin Khlebnikov
2014-04-02 19:07     ` Kirill A. Shutemov
2014-04-02 19:07       ` Kirill A. Shutemov
2014-02-27 21:28 ` [PATCHv3 0/2] mm: map few pages around fault address if they are in " Linus Torvalds
2014-02-27 21:28   ` Linus Torvalds
2014-02-28  0:10   ` Kirill A. Shutemov
2014-02-28  0:10     ` Kirill A. Shutemov
2014-02-28  3:52     ` Wilcox, Matthew R
2014-02-28  3:52       ` Wilcox, Matthew R
2014-02-28 23:08     ` Linus Torvalds [this message]
2014-02-28 23:08       ` Linus Torvalds
2014-03-12 14:22   ` Kirill A. Shutemov
2014-03-12 14:22     ` Kirill A. Shutemov

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