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Date: Thu, 26 Jan 2012 17:05:15 +0100
From: Orjan Friberg <of@flatfrog.com>
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To: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Subject: Re: JFFS2 oops when writing to two partitions simultaneously
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On 01/26/2012 04:25 PM, Orjan Friberg wrote:
> On 01/26/2012 04:17 PM, Joakim Tjernlund wrote:
>> You could try removing the lock dropping, one at a time, to see if it makes a difference.
>> That would be a data point for anyone wanting to fix this.
>
> I'll turn on CONFIG_DEBUG_SPINLOCK and CONFIG_DEBUG_SPINLOCK_SLEEP and
> see what happens.

As expected, dropping the lock around kmalloc was fine once I changed 
GFP_KERNEL to GFP_ATOMIC.

Dropping the lock around kfree worked fine (I didn't think it would).

And, as you suggested, we could probably combine those.


We must hold the lock when calling this->compress (to protect compr_buf; 
we oops without it) but in doing so I get

BUG: sleeping function called from invalid context at kernel/mutex.c:85

because jffs2_lzo_compress does a mutex_lock.


Even if it did work, I think we'd unneccessarily be limiting the 
throughput in that piece of code by holding the lock for that long.

-- 
Orjan Friberg
FlatFrog Laboratories AB