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From: Dave Chinner <david@fromorbit.com>
To: Juergen Urban <JuergenUrban@gmx.de>
Cc: xfs@oss.sgi.com
Subject: Re: BUG() in end_page_writeback(), stack overflows and system speed decrease with XFS over USB
Date: Sun, 22 Nov 2009 09:04:44 +1100	[thread overview]
Message-ID: <20091121220444.GF3804@discord.disaster> (raw)
In-Reply-To: <200911211833.20691.JuergenUrban@gmx.de>

On Sat, Nov 21, 2009 at 06:33:20PM +0100, Juergen Urban wrote:
> Can someone explain the purpose of the BUG() in end_page_writeback()? Can I 
> remove the line?

A page that is under writeback is supposed to have the PG_writeback
flag set. Hence when writeback is completed (i.e the page is now
clean) we need to clear the PG_writeback bit. The BUG is triggered
if we are ending writeback on a page that does not have PG_writeback
set. IOWs, something is seriously wrong, and could be a memory error
or memory corruption.

> Will XFS also work if I disable all address operations?

No.

> What is the purpose of the address operations?

Reading Documentation/filesystems/vfs.txt might answer your
questions....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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      reply	other threads:[~2009-11-21 22:04 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-19  8:57 BUG() in end_page_writeback(), stack overflows and system speed decrease with XFS over USB Juergen Urban
2009-11-19 18:00 ` Eric Sandeen
2009-11-20 16:23   ` Juergen Urban
2009-11-20 16:36     ` Eric Sandeen
2009-11-20 17:08       ` Eric Sandeen
2009-11-21  1:00         ` Juergen Urban
2009-11-21 10:51           ` Michael Monnerie
2009-11-21 17:33             ` Juergen Urban
2009-11-21 22:04               ` Dave Chinner [this message]

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