From: Nick Piggin <npiggin@suse.de>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Andrew Morton <akpm@osdl.org>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Linux Memory Management <linux-mm@kvack.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: SPAM: Re: SPAM: Re: [patch 2/5] mm: fault vs invalidate/truncate race fix
Date: Wed, 11 Oct 2006 19:21:20 +0200 [thread overview]
Message-ID: <20061011172120.GC5259@wotan.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0610111007000.3952@g5.osdl.org>
On Wed, Oct 11, 2006 at 10:11:43AM -0700, Linus Torvalds wrote:
>
>
> On Wed, 11 Oct 2006, Nick Piggin wrote:
> > >
> > > The original IO could have been started by a person who didn't have
> > > permissions to actually carry it out successfully, so if you enter with
> > > the page locked (because somebody else started the IO), and you wait for
> > > the page and it's not up-to-date afterwards, you absolutely _have_ to try
> > > the IO, and can only return a real IO error after your _own_ IO has
> > > failed.
> >
> > Sure, but we currently try to read _twice_, don't we?
>
> Well, we have the read-ahead, and then the real read. By the time we do
> the real read, we have forgotten about the read-ahead details, so..
I mean filemap_nopage does *two* synchronous reads when finding a !uptodate
page. This is despite the comment saying that it retries once on error.
WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <npiggin@suse.de>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Andrew Morton <akpm@osdl.org>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Linux Memory Management <linux-mm@kvack.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: SPAM: Re: SPAM: Re: [patch 2/5] mm: fault vs invalidate/truncate race fix
Date: Wed, 11 Oct 2006 19:21:20 +0200 [thread overview]
Message-ID: <20061011172120.GC5259@wotan.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0610111007000.3952@g5.osdl.org>
On Wed, Oct 11, 2006 at 10:11:43AM -0700, Linus Torvalds wrote:
>
>
> On Wed, 11 Oct 2006, Nick Piggin wrote:
> > >
> > > The original IO could have been started by a person who didn't have
> > > permissions to actually carry it out successfully, so if you enter with
> > > the page locked (because somebody else started the IO), and you wait for
> > > the page and it's not up-to-date afterwards, you absolutely _have_ to try
> > > the IO, and can only return a real IO error after your _own_ IO has
> > > failed.
> >
> > Sure, but we currently try to read _twice_, don't we?
>
> Well, we have the read-ahead, and then the real read. By the time we do
> the real read, we have forgotten about the read-ahead details, so..
I mean filemap_nopage does *two* synchronous reads when finding a !uptodate
page. This is despite the comment saying that it retries once on error.
--
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next prev parent reply other threads:[~2006-10-11 17:21 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-10 14:21 [rfc] 2.6.19-rc1-git5: consolidation of file backed fault handlers Nick Piggin
2006-10-10 14:21 ` Nick Piggin
2006-10-10 14:21 ` [patch 1/5] mm: fault vs invalidate/truncate check Nick Piggin
2006-10-10 14:21 ` Nick Piggin
2006-10-10 14:21 ` [patch 2/5] mm: fault vs invalidate/truncate race fix Nick Piggin
2006-10-10 14:21 ` Nick Piggin
2006-10-11 4:38 ` Andrew Morton
2006-10-11 4:38 ` Andrew Morton
2006-10-11 5:39 ` Nick Piggin
2006-10-11 5:39 ` Nick Piggin
2006-10-11 6:00 ` Andrew Morton
2006-10-11 6:00 ` Andrew Morton
2006-10-11 9:21 ` Nick Piggin
2006-10-11 9:21 ` Nick Piggin
2006-10-11 16:21 ` Linus Torvalds
2006-10-11 16:21 ` Linus Torvalds
2006-10-11 16:57 ` SPAM: " Nick Piggin
2006-10-11 16:57 ` Nick Piggin
2006-10-11 17:11 ` Linus Torvalds
2006-10-11 17:11 ` Linus Torvalds
2006-10-11 17:21 ` Nick Piggin [this message]
2006-10-11 17:21 ` SPAM: " Nick Piggin
2006-10-11 17:38 ` Linus Torvalds
2006-10-11 17:38 ` Linus Torvalds
2006-10-12 3:33 ` Nick Piggin
2006-10-12 3:33 ` Nick Piggin
2006-10-12 15:37 ` Linus Torvalds
2006-10-12 15:37 ` Linus Torvalds
2006-10-12 15:40 ` Nick Piggin
2006-10-12 15:40 ` Nick Piggin
2006-10-11 5:13 ` Andrew Morton
2006-10-11 5:13 ` Andrew Morton
2006-10-11 5:50 ` Nick Piggin
2006-10-11 5:50 ` Nick Piggin
2006-10-11 6:10 ` Andrew Morton
2006-10-11 6:10 ` Andrew Morton
2006-10-11 6:17 ` [patch 1/6] revert "generic_file_buffered_write(): handle zero length iovec segments" Andrew Morton
2006-10-11 6:17 ` Andrew Morton, Andrew Morton
[not found] ` <20061010231150.fb9e30f5.akpm@osdl.org>
2006-10-11 6:17 ` [patch 2/6] revert "generic_file_buffered_write(): deadlock on vectored write" Andrew Morton
2006-10-11 6:17 ` Andrew Morton, Andrew Morton
[not found] ` <20061010231243.bc8b834c.akpm@osdl.org>
2006-10-11 6:17 ` [patch 3/6] generic_file_buffered_write() cleanup Andrew Morton
2006-10-11 6:17 ` Andrew Morton, Andrew Morton
[not found] ` <20061010231339.a79c1fae.akpm@osdl.org>
2006-10-11 6:18 ` [patch 4/6] generic_file_buffered_write(): fix page prefaulting Andrew Morton
2006-10-11 6:18 ` Andrew Morton, Andrew Morton
[not found] ` <20061010231424.db88931f.akpm@osdl.org>
2006-10-11 6:18 ` [patch 5/6] generic_file_buffered_write(): max_len cleanup Andrew Morton
2006-10-11 6:18 ` Andrew Morton, Andrew Morton
[not found] ` <20061010231514.c1da7355.akpm@osdl.org>
2006-10-11 6:18 ` [patch 6/6] fix pagecache write deadlocks Andrew Morton
2006-10-11 6:18 ` Andrew Morton, Andrew Morton
2006-10-21 1:53 ` [patch 2/5] mm: fault vs invalidate/truncate race fix Benjamin Herrenschmidt
2006-10-21 1:53 ` Benjamin Herrenschmidt
2006-10-10 14:22 ` [patch 3/5] mm: fault handler to replace nopage and populate Nick Piggin
2006-10-10 14:22 ` Nick Piggin
2006-10-10 14:22 ` [patch 4/5] mm: add vm_insert_pfn helpler Nick Piggin
2006-10-10 14:22 ` Nick Piggin
2006-10-11 10:12 ` Thomas Hellstrom
2006-10-11 11:24 ` Nick Piggin
2006-10-11 21:30 ` Thomas Hellström
2006-10-10 14:22 ` [patch 5/5] mm: merge nopfn with fault handler Nick Piggin
2006-10-10 14:22 ` Nick Piggin
2006-10-10 14:26 ` [rfc] 2.6.19-rc1-git5: consolidation of file backed fault handlers Nick Piggin
2006-10-10 14:26 ` Nick Piggin
2006-10-10 14:33 ` Christoph Hellwig
2006-10-10 14:33 ` Christoph Hellwig
2006-10-10 15:01 ` Nick Piggin
2006-10-10 15:01 ` Nick Piggin
2006-10-10 16:09 ` Arjan van de Ven
2006-10-10 16:09 ` Arjan van de Ven
2006-10-11 0:46 ` SPAM: " Nick Piggin
2006-10-11 0:46 ` Nick Piggin
2006-10-10 15:07 ` Arjan van de Ven
2006-10-10 15:07 ` Arjan van de Ven
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