linux-kernel - Re: Page allocation failure on v3.8-rc5

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Date:	Fri, 1 Feb 2013 08:33:12 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	balbi@...com, Linux USB Mailing List <linux-usb@...r.kernel.org>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Jens Axboe <axboe@...nel.dk>
Subject: Re: Page allocation failure on v3.8-rc5

On Fri, Feb 1, 2013 at 7:43 AM, Andrew Morton <akpm@...ux-foundation.org> wrote:
> On Wed, 30 Jan 2013 19:53:22 +0800
> Ming Lei <ming.lei@...onical.com> wrote:
>
>> The allocation failure is caused by the big sizeof(struct parsed_partitions),
>> which is 64K in my 32bit box,
>
> Geeze.
>
> We could fix that nicely by making parsed_partitions.parts an array of
> pointers to a single `struct parsed_partition' and allocating those
> on-demand.
>
> But given the short-lived nature of this storage and the infrequency of
> check_partition(), that isn't necessary.
>
>> could you test the blow patch to see
>> if it can fix the allocation failure?
>
> (The patch is wordwrapped)

Sorry for that, I send out it for test.

>
>> ...
>>
>> @@ -106,18 +107,43 @@ static int (*check_part[])(struct parsed_partitions *) = {
>>       NULL
>>  };
>>
>> +struct parsed_partitions *allocate_partitions(int nr)
>> +{
>> +     struct parsed_partitions *state;
>> +
>> +     state = kzalloc(sizeof(struct parsed_partitions), GFP_KERNEL);
>
> I personally prefer sizefo(*state) here.  It means the reader doesn't
> have to scroll back to check things.

OK, will use sizeof(*state).

>> +     if (!state)
>> +             return NULL;
>> +
>> +     state->parts = vzalloc(nr * sizeof(state->parts[0]));
>> +     if (!state->parts) {
>> +             kfree(state);
>> +             return NULL;
>> +     }
>
> It doesn't really need to be this complex - we could just vmalloc the
> entire `struct parsed_partitions'.  But I see that your change will

The above approach can save one 32K allocation approximately.

> cause us to allcoate much less memory in many situations, which is
> good.  It should be mentioned in the changelog!

OK, I will add the changelog later.


Thanks,
--
Ming Lei
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