linux-kernel - Re: [PATCH v2] mm: BUG when __kmap_atomic_idx equals KM_TYPE

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Message-ID: <53DF5184.1040501@codeaurora.org>
Date:	Mon, 04 Aug 2014 14:55:24 +0530
From:	Chintan Pandya <cpandya@...eaurora.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	David Rientjes <rientjes@...gle.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH v2] mm: BUG when __kmap_atomic_idx equals KM_TYPE_NR

On 08/01/2014 04:15 AM, Andrew Morton wrote:
> On Thu, 31 Jul 2014 14:58:58 +0530 Chintan Pandya<cpandya@...eaurora.org>  wrote:
>
>>>
>>> I think Andrew's comment earlier was referring to the changelog only and
>>> not the patch, which looked correct.
>>
>> I think Andrew asked for a BUG case details also to justify the
>> overhead. But we have never encountered that BUG case. Present patch is
>> only logical fix to the code. However, in the fast path, if such
>> overhead is allowed, I can move BUG_ON out of any debug configs.
>> Otherwise, as per Andrew's suggestion, I will convert DEBUG_HIGHMEM into
>> DEBUG_VM which is used more frequently.
>
> The v1 patch added a small amount of overhead to kmap_atomic() for what
> is evidently a very small benefit.
>
> Yes, I suggest we remove CONFIG_DEBUG_HIGHMEM from the kernel entirely
> and switch all CONFIG_DEBUG_HIGHMEM sites to use CONFIG_DEBUG_VM.  That way
> the BUG_ON which you believe is useful will be tested by more people
> more often.

Ping!! Anything open for me to do here ?

-- 
Chintan Pandya

QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
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