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

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Message-ID: <3643399.LsrOz08NF9@phil>
Date:   Sat, 17 Dec 2016 01:48:33 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     Matthew Wilcox <mawilcox@...rosoft.com>
Cc:     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>
Subject: Re: thermal zones break with patch "Reimplement IDR and IDA using the radix tree" (mainline+next)

Hi Matthew,

Am Freitag, 16. Dezember 2016, 21:19:37 CET schrieb Matthew Wilcox:
> 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/c52eeed7b759c3
> fefe9b7f1b0a17a438df6950f3

yay, this fixes the issue. This should definitly go as fix into 4.10-rc and when 
you send it to Andrew you can add my

Tested-by: Heiko Stuebner <heiko@...ech.de>

 
> Now ... thermal is actually using an IDR when it could save memory by using
> an IDA.  Are you interested in doing that conversion?

That would more be a question for Eduardo and Rui :-) . I'm just in the 
process of tracking down the smallish issues on my Rockchip board that are 
poping up during the merge-window.


Anyway, thanks for pointing to the fix
Heiko