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SubjectRe: [PATCH] mm/migrate: Mark unmap_and_move() "noinline" to avoid ICE in gcc 4.7.3
Date
Andrew Morton <akpm@linux-foundation.org> writes:

> On Wed, 01 Apr 2015 10:47:49 +0100 Marc Zyngier <marc.zyngier@arm.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.

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

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