linux-kernel - [PATCH v2] x86/mce: fix wrong no-return-ip logic in do_machine

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Date:   Mon, 22 Feb 2021 11:50:07 +0800
From:   Aili Yao <yaoaili@...gsoft.com>
To:     <tony.luck@...el.com>, <bp@...en8.de>, <mingo@...hat.com>,
        <tglx@...utronix.de>, <hpa@...or.com>
CC:     <x86@...nel.org>, <linux-edac@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <yangfeng1@...gsoft.com>,
        <yaoaili@...gsoft.com>
Subject: [PATCH v2] 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's coredump step in kernel will touch the error page again,
which 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 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index e133ce1e562b..70380d7d98b3 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1414,7 +1414,10 @@ noinstr void do_machine_check(struct pt_regs *regs)
 		/* 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 {
 		/*
-- 
2.25.1