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Subject: Re: [RFC PATCH 2/2] mtd: ubi: wl: avoid erasing a PEB which is empty
To: Richard Weinberger <richard@nod.at>, linux-mtd@lists.infradead.org
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Cc: David Woodhouse <dwmw2@infradead.org>,
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Tue, 24 Nov 2015 09:42:48 +0100
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On 11/24/2015 09:39 AM, Richard Weinberger wrote:
>>>> +	} else {
>>>> +		err = do_sync_erase(ubi, e2, vol_id, lnum, torture);
>>>> +		if (err) {
>>>> +			wl_entry_destroy(ubi, e2);
>>>
>>> Why that? The erase_worker will free e2 if it encounters
>>> a fatal error and gives up this PEB. You're introducing a double free.
>>
>> Hmmm. That is real bad error handling you have there. So you invoke
>> do_sync_erase(), the kmalloc() fails and how exactly you free e2 here?
> 
> Why do you want to free e2? We free an erase entry only if we give
> it up. wear leveling entries are allocated at init time and destroyed
> when you detach UBI.

The reference to it in the RB-tree (free) was removed. Is there another
reference to it?

> Thanks,
> //richard
> 

Sebastian