linux-kernel - Re: thermal zones break with patch "Reimplement IDR and IDA using the radix tree" (mainline+next)

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Date:   Sun, 18 Dec 2016 21:43:19 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Matthew Wilcox <mawilcox@...rosoft.com>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Vinod Koul <vinod.koul@...el.com>
Subject: Re: thermal zones break with patch "Reimplement IDR and IDA using the
 radix tree" (mainline+next)

On Fri, Dec 16, 2016 at 11:19 PM, Matthew Wilcox <mawilcox@...rosoft.com> wrote:
> From: Heiko Stuebner [mailto:heiko@...ech.de]
>> commit b05bbe3ea2db ("Reimplement IDR and IDA using the radix tree")
>> seems to
>> break thermal zone allocation. This happens both on todays mainline and
>> linux-next-20161216 and produces errors like:
>
>> While I haven't looked to deeply into what idr exactly does, some findings:
>> - thermal_zone0 and thermal_zone1 are allocated correctly
>> - every further thermal_zone always gets allocated the number "1"
>> - thermal core calls idr_alloc with 0 for both start and end
>> - the rewrite-patch seems to change the semantics of idr_alloc
>>   where it orignally said "@end: the maximum id (exclusive, <= 0 for max)"
>>   the "<= 0" part is gone now, but I checked, simply setting INT_MAX
>>   as end in the thermal_core does not help
>
> Hi Heiko,
>
> Thanks for the report!  The problem is because the thermal subsystem calls idr_alloc() passing a NULL pointer for the data.  I have fixed this problem in my git tree but haven't sent the patch to Andrew yet.  This patch should fix the problem for you:
>
> http://git.infradead.org/users/willy/linux-dax.git/commitdiff/c52eeed7b759c3fefe9b7f1b0a17a438df6950f3
>
> Now ... thermal is actually using an IDR when it could save memory by using an IDA.  Are you interested in doing that conversion?

+Cc: Mika, Vinod

Same here for at least DMA Engine (and perhaps another place in
thermal subsystem).

For DMA Engine case

Tested-by: Andy Shevchenko <andy.shevchenko@...il.com>

-- 
With Best Regards,
Andy Shevchenko