linux-kernel - Re: [PATCH] mtd: Allocate bdi objects dynamically

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Date:   Sat, 5 Nov 2016 08:22:31 +0100
From:   Marek Vasut <marek.vasut@...il.com>
To:     Sandeep Jain <Sandeep_Jain@...tor.com>,
        Richard Weinberger <richard.weinberger@...il.com>
Cc:     Steve Longerbeam <steve_longerbeam@...tor.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Jim Baxter <jim_baxter@...tor.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH] mtd: Allocate bdi objects dynamically

On 11/03/2016 12:34 PM, Sandeep Jain wrote:
> Dear Maintainers,
>   This patch is reviewed by Richard.
> Requesting for Maintainer's attention for patch merge.
> 
> Thanks & Regards,
> Sandeep Jain
> 
> On Sat, Sep 17, 2016 at 04:41:47PM +0200, Richard Weinberger wrote:
>> On Thu, Aug 4, 2016 at 4:01 PM, Sandeep Jain <Sandeep_Jain@...tor.com> wrote:
>>> From: Steve Longerbeam <steve_longerbeam@...tor.com>
>>>
>>> The MTD backing dev info objects mtd_bdi was statically allocated.
>>> So when MTD is built as a loadable module, this object fall in the
>>> vmalloc address space.
>>>
>>> The problem with that, is that the BDI APIs use wake_up_bit(), which calls
>>> virt_to_page() to retrieve the memory zone of the page containing the
>>> wait_queue to wake up, and virt_to_page() is not valid for vmalloc or
>>> highmem addresses.
>>>
>>> Fix this by allocating the BDI objects dynamically with kmalloc. The
>>> objects now fall in the logical address space so that BDI APIs will
>>> work in all cases (mtd builtin or module).
>>>
>>> Signed-off-by: Steve Longerbeam <steve_longerbeam@...tor.com>
>>> Signed-off-by: Jim Baxter <jim_baxter@...tor.com>
>>> Signed-off-by: Sandeep Jain <Sandeep_Jain@...tor.com>
>>
>> Reviewed-by: Richard Weinberger <richard@....at>

I don't see any obvious problem either:
Reviewed-by: Marek Vasut <marek.vasut@...il.com>

-- 
Best regards,
Marek Vasut