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Commit f29a7aff authored by Chen, Gong's avatar Chen, Gong Committed by Ingo Molnar
Browse files

x86/mce: Avoid potential deadlock due to printk() in MCE context 



Printing in MCE context is a no-no, currently, as printk() is
not NMI-safe. If some of the notifiers on the MCE chain call do
so, we may deadlock. In order to avoid that, delay printk() to
process context where it is safe.

Reported-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: default avatarChen, Gong <gong.chen@linux.intel.com>
[ Fold in subsequent patch from Boris for early boot logging. ]
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
[ Kick irq_work in mce_log() directly. ]
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1439396985-12812-6-git-send-email-bp@alien8.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent fd4cf79f

arch/x86/kernel/cpu/mcheck/mce-apei.c

+0 −1
Original line number Diff line number Diff line
@@ -57,7 +57,6 @@ void apei_mce_report_mem_error(int severity, struct cper_sec_mem_err *mem_err) 


	m.addr = mem_err->physical_addr;

	mce_log(&m);

	mce_notify_irq();

}

EXPORT_SYMBOL_GPL(apei_mce_report_mem_error);

arch/x86/kernel/cpu/mcheck/mce.c

+2 −2
Original line number Diff line number Diff line
@@ -159,7 +159,8 @@ void mce_log(struct mce *mce) 
	/* Emit the trace record: */

	trace_mce_record(mce);



	atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);

	if (!mce_gen_pool_add(mce))

		irq_work_queue(&mce_irq_work);



	mce->finished = 0;

	wmb();
@@ -1122,7 +1123,6 @@ void do_machine_check(struct pt_regs *regs, long error_code) 
		/* assuming valid severity level != 0 */

		m.severity = severity;

		m.usable_addr = mce_usable_address(&m);

		mce_gen_pool_add(&m);



		mce_log(&m);

arch/x86/kernel/cpu/mcheck/mce_intel.c

+0 −1
Original line number Diff line number Diff line
@@ -246,7 +246,6 @@ static void intel_threshold_interrupt(void) 
		return;



	machine_check_poll(MCP_TIMESTAMP, this_cpu_ptr(&mce_banks_owned));

	mce_notify_irq();

}



/*