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

[Kevin Hilman]

Hi Andrew,

On Wed, Apr 1, 2015 at 2:54 PM, Kevin Hilman <khilman@xxxxxxxxxx> wrote:
> Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:
>
>> On Wed, 01 Apr 2015 10:47:49 +0100 Marc Zyngier <marc.zyngier@xxxxxxx> 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 my fix in your mmots since last Thurs (4/2), but it's not in
mmotm (last updated today) so today's linux-next still has the ICE for
anything other than gcc-4.7.3.   Just checking to see when you plan to
update mmotm.

Thanks,

Kevin
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