This is a note to let you know that I've just added the patch titled
compiler/gcc4: Make quirk for asm_volatile_goto() unconditional
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
compiler-gcc4-make-quirk-for-asm_volatile_goto-unconditional.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a9f180345f5378ac87d80ed0bea55ba421d83859 Mon Sep 17 00:00:00 2001
From: Steven Noonan <steven@xxxxxxxxxxxxxx>
Date: Wed, 12 Feb 2014 23:01:07 -0800
Subject: compiler/gcc4: Make quirk for asm_volatile_goto() unconditional
From: Steven Noonan <steven@xxxxxxxxxxxxxx>
commit a9f180345f5378ac87d80ed0bea55ba421d83859 upstream.
I started noticing problems with KVM guest destruction on Linux
3.12+, where guest memory wasn't being cleaned up. I bisected it
down to the commit introducing the new 'asm goto'-based atomics,
and found this quirk was later applied to those.
Unfortunately, even with GCC 4.8.2 (which ostensibly fixed the
known 'asm goto' bug) I am still getting some kind of
miscompilation. If I enable the asm_volatile_goto quirk for my
compiler, KVM guests are destroyed correctly and the memory is
cleaned up.
So make the quirk unconditional for now, until bug is found
and fixed.
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Noonan <steven@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Jakub Jelinek <jakub@xxxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1392274867-15236-1-git-send-email-steven@xxxxxxxxxxxxxx
Link: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/compiler-gcc4.h | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -75,11 +75,7 @@
*
* (asm goto is automatically volatile - the naming reflects this.)
*/
-#if GCC_VERSION <= 40801
-# define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
-#else
-# define asm_volatile_goto(x...) do { asm goto(x); } while (0)
-#endif
+#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
#if GCC_VERSION >= 40400
Patches currently in stable-queue which might be from steven@xxxxxxxxxxxxxx are
queue-3.12/compiler-gcc4-make-quirk-for-asm_volatile_goto-unconditional.patch
queue-3.12/xen-properly-account-for-_page_numa-during-xen-pte-translations.patch
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