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

[Lina Iyer]

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@xxxxxxxxxx> wrote:
> > On Wed, Apr 01 2015 at 15:57 -0600, Kevin Hilman 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 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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