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Commit f8bc0881 authored by Vishal Verma's avatar Vishal Verma Committed by Greg Kroah-Hartman
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x86/mce: Make the MCE notifier a blocking one 



commit 0dc9c639e6553e39c13b2c0d54c8a1b098cb95e2 upstream.

The NFIT MCE handler callback (for handling media errors on NVDIMMs)
takes a mutex to add the location of a memory error to a list. But since
the notifier call chain for machine checks (x86_mce_decoder_chain) is
atomic, we get a lockdep splat like:

  BUG: sleeping function called from invalid context at kernel/locking/mutex.c:620
  in_atomic(): 1, irqs_disabled(): 0, pid: 4, name: kworker/0:0
  [..]
  Call Trace:
   dump_stack
   ___might_sleep
   __might_sleep
   mutex_lock_nested
   ? __lock_acquire
   nfit_handle_mce
   notifier_call_chain
   atomic_notifier_call_chain
   ? atomic_notifier_call_chain
   mce_gen_pool_process

Convert the notifier to a blocking one which gets to run only in process
context.

Boris: remove the notifier call in atomic context in print_mce(). For
now, let's print the MCE on the atomic path so that we can make sure
they go out and get logged at least.

Fixes: 6839a6d9 ("nfit: do an ARS scrub on hitting a latent media error")
Reported-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Acked-by: default avatarTony Luck <tony.luck@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/20170411224457.24777-1-vishal.l.verma@intel.com


Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6966a657

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

+1 −1
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ void mce_gen_pool_process(void) 
	head = llist_reverse_order(head);

	llist_for_each_entry_safe(node, tmp, head, llnode) {

		mce = &node->mce;

		atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);

		blocking_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);

		gen_pool_free(mce_evt_pool, (unsigned long)node, sizeof(*node));

	}

}

arch/x86/kernel/cpu/mcheck/mce-internal.h

+1 −1
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ enum severity_level { 
	MCE_PANIC_SEVERITY,

};



extern struct atomic_notifier_head x86_mce_decoder_chain;

extern struct blocking_notifier_head x86_mce_decoder_chain;



#define ATTR_LEN		16

#define INITIAL_CHECK_INTERVAL	5 * 60 /* 5 minutes */

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

+3 −13
Original line number Diff line number Diff line
@@ -120,7 +120,7 @@ static void (*quirk_no_way_out)(int bank, struct mce *m, struct pt_regs *regs); 
 * CPU/chipset specific EDAC code can register a notifier call here to print

 * MCE errors in a human-readable form.

 */

ATOMIC_NOTIFIER_HEAD(x86_mce_decoder_chain);

BLOCKING_NOTIFIER_HEAD(x86_mce_decoder_chain);



/* Do initial initialization of a struct mce */

void mce_setup(struct mce *m)
@@ -213,13 +213,13 @@ void mce_register_decode_chain(struct notifier_block *nb) 
	if (nb != &mce_srao_nb && nb->priority == INT_MAX)

		nb->priority -= 1;



	atomic_notifier_chain_register(&x86_mce_decoder_chain, nb);

	blocking_notifier_chain_register(&x86_mce_decoder_chain, nb);

}

EXPORT_SYMBOL_GPL(mce_register_decode_chain);



void mce_unregister_decode_chain(struct notifier_block *nb)

{

	atomic_notifier_chain_unregister(&x86_mce_decoder_chain, nb);

	blocking_notifier_chain_unregister(&x86_mce_decoder_chain, nb);

}

EXPORT_SYMBOL_GPL(mce_unregister_decode_chain);
@@ -272,8 +272,6 @@ struct mca_msr_regs msr_ops = { 


static void print_mce(struct mce *m)

{

	int ret = 0;



	pr_emerg(HW_ERR "CPU %d: Machine Check Exception: %Lx Bank %d: %016Lx\n",

	       m->extcpu, m->mcgstatus, m->bank, m->status);
@@ -309,14 +307,6 @@ static void print_mce(struct mce *m) 
		m->cpuvendor, m->cpuid, m->time, m->socketid, m->apicid,

		cpu_data(m->extcpu).microcode);



	/*

	 * Print out human-readable details about the MCE error,

	 * (if the CPU has an implementation for that)

	 */

	ret = atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m);

	if (ret == NOTIFY_STOP)

		return;



	pr_emerg_ratelimited(HW_ERR "Run the above through 'mcelog --ascii'\n");

}