linux-kernel - Re: s390x: kernel BUG at fs/ext4/inode.c:1591! (powerpc too!)

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Message-ID: <87r4isd1vn.fsf@openvz.org>
Date:	Wed, 03 Apr 2013 02:05:48 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	Christian Kujau <lists@...dbynature.de>
Cc:	CAI Qian <caiqian@...hat.com>, Theodore Ts'o <tytso@....edu>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-s390 <linux-s390@...r.kernel.org>,
	Steve Best <sbest@...hat.com>, linux-ext4@...r.kernel.org,
	Zheng Liu <gnehzuil.liu@...il.com>
Subject: Re: s390x: kernel BUG at fs/ext4/inode.c:1591! (powerpc too!)

On Tue, 2 Apr 2013 14:35:29 -0700 (PDT), Christian Kujau <lists@...dbynature.de> wrote:
> On Tue, 2 Apr 2013 at 13:47, Dmitry Monakhov wrote:
> > So you just do bunch of writes/mmap to fallocated area.
> > The only guess I have is that some bug in extent status tree
> > 
> > Please run test with a patch which was posted here:
> > http://marc.info/?l=linux-kernel&m=136455173926544&w=2
> > This patch enable sanity checks for extent_status tree.
> > Also please try following patch. It voluntary disable es_lookup functionality.
> 
> I tested your patch below (applied to 3.9-rc4) and now the BUG is gone. 
> The machine stays up and the corruption of that torrent file is gone too! 
> 
> Feel free to add my Tested-by: but I don't know if this will be the final 
> solution to this issue, no?
No. This is just a proof that es_cache is a root of cause.
Please drop that patch and collect logs with a kernel which 
has only 0001-enable-ES_AGGRESSIVE_TEST-V2.patch patch applied
This can help us understand what was wrong. From CAI Qian's
logs(http://marc.info/?l=linux-ext4&m=136489690730402&w=2) 
I found that in most cases assertion failed because
ec_cache contains BH_Mapped entries, but extent_tree has not data at all

Also there is another assertion failure where
es_cache {15/1/33490/MAPPED}  != extent_tree {15/1/33579/BH_UNWRITTEN}

> 
> Thanks!
> Christian.
> 
> diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c> index fe3337a..95d27cd 100644
> --- a/fs/ext4/extents_status.c
> +++ b/fs/ext4/extents_status.c
> @@ -689,6 +689,7 @@ int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
>  	trace_ext4_es_lookup_extent_enter(inode, lblk);
>  	es_debug("lookup extent in block %u\n", lblk);
>  
> +	return 0;
>  	tree = &EXT4_I(inode)->i_es_tree;
>  	read_lock(&EXT4_I(inode)->i_es_lock);
>  
> -- 
> BOFH excuse #414:
> 
> tachyon emissions overloading the system
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