linux-kernel - Re: mount -o loop with truncated dosdisk.img uses 100% cpu and can't be killed

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Message-ID: <x49obnj3bgw.fsf@segfault.boston.devel.redhat.com>
Date:	Fri, 13 Jul 2012 11:52:15 -0400
From:	Jeff Moyer <jmoyer@...hat.com>
To:	Jan Kara <jack@...e.cz>
Cc:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
	"Steven J. Magnani" <steve@...idescorp.com>,
	Stevie Trujillo <stevie.trujillo@...il.com>,
	linux-kernel@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Subject: Re: mount -o loop with truncated dosdisk.img uses 100% cpu and can't be killed

Jan Kara <jack@...e.cz> writes:

>> It looks like the bug of __getblk_slow(). If requested block was beyond
>> end of device, __find_get_block() will find buffer_mapped()'s buffer,
>> but block >= end_block is unmapped. So, it can be loop.
>> 
>> The following patch fixes it? If it fix, there are some options to check
>> it.
>> 
>> a) Check it like this patch and warn.
>> b) (a), but without warn.
>> c) Check it in init_page_buffers() and return -EIO or such
>> 
>> Well, anyway, Cc to Jens.
>> 
>> Signed-off-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
>   I think Jeff Moyer has sent a similar fix recently. It may even be
> already queued in Jens' tree. Jeff?

I haven't heard a peep from Jens (I believe he's been on vacation), so I
forwarded the patch along to Linus (but haven't heard anything from him,
either).

See my email with Subject: [patch] block: fix infinite loop in __getblk_slow
  https://lkml.org/lkml/2012/6/26/252

Cheers,
Jeff
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