Re: Highmem issues with MMC filesystem

["Hemanth V" <hemanthv@ti.com>]

----- Original Message ----- 
From: "Russell King - ARM Linux" <linux@arm.linux.org.uk>
To: "Shilimkar, Santosh" <santosh.shilimkar@ti.com>
Cc: "Nicolas Pitre" <nico@fluxnic.net>; <linux-mmc@vger.kernel.org>; "V, 
Hemanth" <hemanthv@ti.com>; "saeed bishara" <saeed.bishara@gmail.com>; 
<pierre@ossman.eu>; <linux-arm-kernel@lists.infradead.org>
Sent: Thursday, March 18, 2010 7:49 PM
Subject: Re: Highmem issues with MMC filesystem


> On Thu, Mar 18, 2010 at 07:00:06PM +0530, Shilimkar, Santosh wrote:
>> Or could it be that there is appropriate cacheflush happening but data 
>> gets
>> stuck in CPU writebuffers instead of reaching to main memory. In this 
>> case
>> too DMA won't see the contents and a barrier (dsb) is necessary to ensure
>> that write buffer is drained before DMA takes over the buffer.
>
> That would imply that the data on the device is becoming corrupted.
>
> What exactly is the problem that we're discussing?  Is it that the data
> on the block device is becoming corrupted, or is the data being read off
> the block device corrupted?
>

It seems like data being read off the block device is being corrupted,
since if we replace highmem kernel with a non-highmem kernel
the filesystem is able to bootup fine.