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FAILED: patch "[PATCH] x86/mce: Make the MCE notifier a blocking one" failed to apply to 4.9-stable tree

PATCH Greg Kroah-Hartman 1 participant 1 message Apr 24, 2017

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Greg Kroah-Hartman

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The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0dc9c639e6553e39c13b2c0d54c8a1b098cb95e2 Mon Sep 17 00:00:00 2001
From: Vishal Verma <[email protected]>
Date: Tue, 18 Apr 2017 20:42:35 +0200
Subject: [PATCH] x86/mce: Make the MCE notifier a blocking one

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 6839a6d96f4e ("nfit: do an ARS scrub on hitting a latent media error")
Reported-by Ross Zwisler <[email protected]>
Signed-off-by Vishal Verma <[email protected]>
Acked-by Tony Luck <[email protected]>
Cc Dan Williams <[email protected]>
Cc linux-edac <[email protected]>
Cc x86-ml <[email protected]>
Cc <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Borislav Petkov <[email protected]>
Signed-off-by Thomas Gleixner <[email protected]>

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arch/x86/kernel/cpu/mcheck/mce-genpool.c +1 -1
index 1e5a50c11d3c..217cd4449bc9 100644
@@ -85,7 +85,7 @@ void mce_gen_pool_process(struct work_struct *__unused)
 	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
index 903043e6a62b..19592ba1a320 100644
@@ -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 -14
index 5accfbdee3f0..af44ebeb593f 100644
@@ -123,7 +123,7 @@ 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)

@@ -220,7 +220,7 @@ void mce_register_decode_chain(struct notifier_block *nb)
 
 	WARN_ON(nb->priority > MCE_PRIO_LOWEST && nb->priority < MCE_PRIO_EDAC);
 
-	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);
 

@@ -228,7 +228,7 @@ void mce_unregister_decode_chain(struct notifier_block *nb)
 {
 	atomic_dec(&num_notifiers);
 
-	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);
 

@@ -321,18 +321,7 @@ static void __print_mce(struct mce *m)
 
 static void print_mce(struct mce *m)
 {
-	int ret = 0;
-
 	__print_mce(m);
-
-	/*
-	 * 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");
 }