linux-kernel - [PATCH] HWPOISON: define VM_FAULT_HWPOISON to 0 when feature is disabled

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Date:	Tue, 9 Jun 2009 20:34:16 +0800
From:	Wu Fengguang <fengguang.wu@...el.com>
To:	Nick Piggin <npiggin@...e.de>
Cc:	Andi Kleen <andi@...stfloor.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: [PATCH] HWPOISON: define VM_FAULT_HWPOISON to 0 when feature is
	disabled

On Tue, Jun 09, 2009 at 05:54:23PM +0800, Nick Piggin wrote:
> On Wed, Jun 03, 2009 at 08:46:40PM +0200, Andi Kleen wrote:

> > -	force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
> > +#ifdef CONFIG_MEMORY_FAILURE
> > +	if (fault & VM_FAULT_HWPOISON) {
> > +		printk(KERN_ERR
> > +	"MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
> > +			tsk->comm, tsk->pid, address);
> > +		code = BUS_MCEERR_AR;
> > +	}
> > +#endif
> 
> If you make VM_FAULT_HWPOISON 0 when !CONFIG_MEMORY_FAILURE, then
> you can remove this ifdef, can't you?

Sure we can. Here is the incremental patch.

---
HWPOISON: define VM_FAULT_HWPOISON to 0 when feature is disabled

So as to eliminate one #ifdef in the c source.

Proposed by Nick Piggin.

CC: Nick Piggin <npiggin@...e.de>
Signed-off-by: Wu Fengguang <fengguang.wu@...el.com>
---
 arch/x86/mm/fault.c |    3 +--
 include/linux/mm.h  |    7 ++++++-
 2 files changed, 7 insertions(+), 3 deletions(-)

--- sound-2.6.orig/arch/x86/mm/fault.c
+++ sound-2.6/arch/x86/mm/fault.c
@@ -819,14 +819,13 @@ do_sigbus(struct pt_regs *regs, unsigned
 	tsk->thread.error_code	= error_code;
 	tsk->thread.trap_no	= 14;
 
-#ifdef CONFIG_MEMORY_FAILURE
 	if (fault & VM_FAULT_HWPOISON) {
 		printk(KERN_ERR
 	"MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
 			tsk->comm, tsk->pid, address);
 		code = BUS_MCEERR_AR;
 	}
-#endif
+
 	force_sig_info_fault(SIGBUS, code, address, tsk);
 }
 
--- sound-2.6.orig/include/linux/mm.h
+++ sound-2.6/include/linux/mm.h
@@ -702,11 +702,16 @@ static inline int page_mapped(struct pag
 #define VM_FAULT_SIGBUS	0x0002
 #define VM_FAULT_MAJOR	0x0004
 #define VM_FAULT_WRITE	0x0008	/* Special case for get_user_pages */
-#define VM_FAULT_HWPOISON 0x0010	/* Hit poisoned page */
 
 #define VM_FAULT_NOPAGE	0x0100	/* ->fault installed the pte, not return page */
 #define VM_FAULT_LOCKED	0x0200	/* ->fault locked the returned page */
 
+#ifdef CONFIG_MEMORY_FAILURE
+#define VM_FAULT_HWPOISON 0x0010	/* Hit poisoned page */
+#else
+#define VM_FAULT_HWPOISON 0
+#endif
+
 #define VM_FAULT_ERROR	(VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_HWPOISON)
 
 /*
--
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