linux-kernel - Re: [PATCH 1/1] mtd: ubi: fix improper return value

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Message-ID: <0446c91c-ac84-3601-203a-9c2e7057f1f9@nod.at>
Date:   Sun, 4 Dec 2016 21:52:17 +0100
From:   Richard Weinberger <richard@....at>
To:     Joe Perches <joe@...ches.com>, Marek Vasut <marek.vasut@...il.com>,
        Pan Bian <bianpan201604@....com>,
        Artem Bityutskiy <dedekind1@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        linux-mtd@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, Pan Bian <bianpan2016@....com>
Subject: Re: [PATCH 1/1] mtd: ubi: fix improper return value

On 04.12.2016 21:33, Joe Perches wrote:
>>> diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
> []
>>> @@ -1413,7 +1413,7 @@ int ubi_self_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
>>>  	buf = __vmalloc(len, GFP_NOFS, PAGE_KERNEL);
>>>  	if (!buf) {
>>>  		ubi_err(ubi, "cannot allocate memory to check for 0xFFs");
>>> -		return 0;
>>> +		return -ENOMEM;
>>
>> I wonder if you shouldn't also nuke the ubi_err() , because when you run
>> out of memory, printk() will likely also fail.
> 
> No, not really.  printk doesn't allocate memory.
> 
> But the ubi_err should be removed because all memory
> allocations that fail without a specific GFP_NOWARN
> flag already have a dump_stack() call.

We should better think about how to get ubi_self_check_all_ff() fixed.
When enabled on a modern NAND, vmalloc() is likely to fail now and then
since len is the erase block size and can be up to a few mega bytes.

Thanks,
//richard