linux-kernel - Re: [PATCH] mm/migrate: Mark unmap_and_move() "noinline" to avoid ICE in gcc 4.7.3

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Message-ID: <20150402215301.GA24500@linaro.org>
Date:	Thu, 2 Apr 2015 15:53:01 -0600
From:	Lina Iyer <lina.iyer@...aro.org>
To:	Kevin Hilman <khilman@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Nishanth Menon <nm@...com>,
	Magnus Damm <magnus.damm@...il.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Tyler Baker <tyler.baker@...aro.org>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	Will Deacon <Will.Deacon@....com>,
	Linux Kernel Development <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Simon Horman <horms@...ge.net.au>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"grygorii.strashko@...aro.org" <grygorii.strashko@...aro.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] mm/migrate: Mark unmap_and_move() "noinline" to avoid
 ICE in gcc 4.7.3

On Thu, Apr 02 2015 at 15:12 -0600, Kevin Hilman wrote:
>On Thu, Apr 2, 2015 at 12:12 PM, Lina Iyer <lina.iyer@...aro.org> wrote:
>> On Wed, Apr 01 2015 at 15:57 -0600, Kevin Hilman wrote:
>>>
>>> Andrew Morton <akpm@...ux-foundation.org> writes:
>>>
>>>> On Wed, 01 Apr 2015 10:47:49 +0100 Marc Zyngier <marc.zyngier@....com>
>>>> wrote:
>>>>
>>>>> > -static int unmap_and_move(new_page_t get_new_page, free_page_t
>>>>> > put_new_page,
>>>>> > -                     unsigned long private, struct page *page, int
>>>>> > force,
>>>>> > -                     enum migrate_mode mode)
>>>>> > +static noinline int unmap_and_move(new_page_t get_new_page,
>>>>> > +                                free_page_t put_new_page,
>>>>> > +                                unsigned long private, struct page
>>>>> > *page,
>>>>> > +                                int force, enum migrate_mode mode)
>>>>> >  {
>>>>> >       int rc = 0;
>>>>> >       int *result = NULL;
>>>>> >
>>>>>
>>>>> Ouch. That's really ugly. And on 32bit ARM, we end-up spilling half of
>>>>> the parameters on the stack, which is not going to help performance
>>>>> either (not that this would be useful on 32bit ARM anyway...).
>>>>>
>>>>> Any chance you could make this dependent on some compiler detection
>>>>> mechanism?
>>>>
>>>>
>>>> With my arm compiler (gcc-4.4.4) the patch makes no difference -
>>>> unmap_and_move() isn't being inlined anyway.
>>>>
>>>> How does this look?
>>>>
>>>> Kevin, could you please retest?  I might have fat-fingered something...
>>>
>>>
>>> Your patch on top of Geert's still compiles fine for me with gcc-4.7.3.
>>> However, I'm not sure how specific we can be on the versions.
>>>
>>> /me goes to test a few more compilers...   OK...
>>>
>>> ICE: 4.7.1, 4.7.3, 4.8.3
>>> OK: 4.6.3, 4.9.2, 4.9.3
>>>
>>> The diff below[2] on top of yours compiles fine here and at least covers
>>> the compilers I *know* to trigger the ICE.
>>
>>
>> I see ICE on arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.7.4-2ubuntu1) 4.7.4
>>
>
>Thanks for checking.  I'm assuming my patch fixes it for your since
>that should catch any 4.7.x compiler.

Yes, thank you. This fixes it on 4.7.4
>
>Kevin
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