[PATCH] mm/migrate: Mark unmap_and_move() "noinline" to avoid ICE in gcc 4.7.3 (was: Re: Possible regression in gcc 4.7.3 next-20150323 due to "ARM, arm64: kvm: get rid of the bounce page")

[Geert Uytterhoeven]

	Hi Kevin,

On Tue, 31 Mar 2015, Kevin Hilman wrote:
> Ard Biesheuvel <ard.biesheuvel at linaro.org> writes:
> Nope, that branch is already part of linux-next, and linux-next still
> fails to compile for 20+ defconfigs[1]
> 
> > Could you elaborate on the issue please? What is the error you are
> > getting, and can you confirm that is is caused by ld choking on the
> > linker script? If not, this is another error than the one we have been
> > trying to fix
> 
> It's definitely not linker script related.
> 
> Using "arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.7.3-12ubuntu1) 4.7.3",
> here's the error when building for multi_v7_defconfig (full log
> available[2]):
> 
> ../mm/migrate.c: In function 'migrate_pages':
> ../mm/migrate.c:1148:1: internal compiler error: in push_minipool_fix, at config/arm/arm.c:13101
> Please submit a full bug report,
> with preprocessed source if appropriate.
> See <file:///usr/share/doc/gcc-4.7/README.Bugs> for instructions.
> Preprocessed source stored into /tmp/ccO1Nz1m.out file, please attach
> this to your bugreport.
> make[2]: *** [mm/migrate.o] Error 1
> make[2]: Target `__build' not remade because of errors.
> make[1]: *** [mm] Error 2
> 
> build bisect points to commit 21f992084aeb[3], but that doesn't revert
> cleanly so I haven't got any further than that yet.

I installed gcc-arm-linux-gnueabi (4:4.7.2-1 from Ubuntu 14.04 LTS) and could
reproduce the ICE. I came up with the workaround below.
Does this work for you?

>From 7ebe83316eaf1952e55a76754ce7a5832e461b8c Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas at glider.be>
Date: Wed, 1 Apr 2015 11:22:51 +0200
Subject: [PATCH] mm/migrate: Mark unmap_and_move() "noinline" to avoid ICE in
 gcc 4.7.3
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

With gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-12ubuntu1) :

    mm/migrate.c: In function ‘migrate_pages’:
    mm/migrate.c:1148:1: internal compiler error: in push_minipool_fix, at config/arm/arm.c:13500
    Please submit a full bug report,
    with preprocessed source if appropriate.
    See <file:///usr/share/doc/gcc-4.7/README.Bugs> for instructions.
    Preprocessed source stored into /tmp/ccPoM1tr.out file, please attach this to your bugreport.
    make[1]: *** [mm/migrate.o] Error 1
    make: *** [mm/migrate.o] Error 2

Mark unmap_and_move() (which is used in a single place only) "noinline"
to work around this compiler bug.

Reported-by: Kevin Hilman <khilman at kernel.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
---
 mm/migrate.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 114602a68111d809..98f8574456c2010c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -904,9 +904,10 @@ out:
  * Obtain the lock on page, remove all ptes and migrate the page
  * to the newly allocated page in newpage.
  */
-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;
-- 
1.9.1


Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds