linux-kernel - [PATCH] x86: fix messed up page fault BUG messages

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Message-ID: <20140813112724.GA6338@localhost>
Date:	Wed, 13 Aug 2014 19:27:24 +0800
From:	Fengguang Wu <fengguang.wu@...el.com>
To:	x86@...nel.org
Cc:	Ingo Molnar <mingo@...hat.com>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: fix messed up page fault BUG messages

The 0day boot test robot hits messed up BUG lines like

[   25.732010] BUG: unable to handle kernel paging requestrun: /lkp/wfg/sr at 000000000000d908
[   24.986598] BUG: unable to handle kernel run: /lkp/wfg/srpaging request at 000000000000d908
[   24.914406] BUG: unable to handle kernel run: /lkp/wfg/srearly console in decompress_kernel

Which makes the generated bug ID not stable and hence not bisectable.

Fix it by printing the BUG message in one shot.

Signed-off-by: Fengguang Wu <fengguang.wu@...el.com>
---
 arch/x86/mm/fault.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3664279..f3e0e0a 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -599,13 +599,13 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
 			printk(nx_warning, from_kuid(&init_user_ns, current_uid()));
 	}
 
-	printk(KERN_ALERT "BUG: unable to handle kernel ");
 	if (address < PAGE_SIZE)
-		printk(KERN_CONT "NULL pointer dereference");
+		printk(KERN_ALERT "BUG: unable to handle kernel NULL pointer dereference at %p\n",
+		       (void *) address);
 	else
-		printk(KERN_CONT "paging request");
+		printk(KERN_ALERT "BUG: unable to handle kernel NULL pointer paging request at %p\n",
+		       (void *) address);
 
-	printk(KERN_CONT " at %p\n", (void *) address);
 	printk(KERN_ALERT "IP:");
 	printk_address(regs->ip);
 
-- 
2.1.0.rc1

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