linux-kernel - x86/mce: fix wrong no-return-ip logic in do_machine

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Date:   Mon, 22 Feb 2021 11:31:24 +0800
From:   Aili Yao <yaoaili@...gsoft.com>
To:     <tony.luck@...el.com>, <bp@...en8.de>, <mingo@...hat.com>,
        <yangfeng1@...gsoft.com>, <yaoaili@...gsoft.com>
CC:     <tglx@...utronix.de>, <x86@...nel.org>, <hpa@...or.com>,
        <linux-edac@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: x86/mce: fix wrong no-return-ip logic in do_machine_check()

>From commit b2f9d678e28c ("x86/mce: Check for faults tagged in
EXTABLE_CLASS_FAULT exception table entries"), When there is a
memory MCE_AR_SEVERITY error with no return ip, Only a SIGBUS
signal is send to current. As the page is not poisoned, the SIGBUS
process coredump step in kernel will touch the error page again,
whick result to a fatal error. We need to poison the page and then
kill current in memory-failure module.

So fix it using the orinigal checking method.

Signed-off-by: Aili Yao <yaoaili@...gsoft.com>
---
 arch/x86/kernel/cpu/mce/core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index e133ce1e562b..ae09b0279422 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1413,9 +1413,10 @@ noinstr void do_machine_check(struct pt_regs *regs)
 	if ((m.cs & 3) == 3) {
 		/* If this triggers there is no way to recover. Die hard. */
 		BUG_ON(!on_thread_stack() || !user_mode(regs));
-
-		queue_task_work(&m, kill_current_task);
-
+		if (worst == MCE_AR_SEVERITY)
+			queue_task_work(&m, 0);
+		else if (kill_current_task)
+			queue_task_work(&m, kill_current_task);
 	} else {
 		/*
 		 * Handle an MCE which has happened in kernel space but from
-- 
2.25.1