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

[Lina Iyer]

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

> Kevin
>
>
> [1]
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 25fd7f6291de..6e15ae3248e0 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -901,10 +901,10 @@ out:
> }
>
> /*
> - * gcc-4.7.3 on arm gets an ICE when inlining unmap_and_move().  Work around
> + * gcc 4.7 and 4.8 on arm gets an ICE when inlining unmap_and_move().  Work around
>  * it.
>  */
> -#if GCC_VERSION == 40703 && defined(CONFIG_ARM)
> +#if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM)
> #define ICE_noinline noinline
> #else
> #define ICE_noinline
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/