The patch titled
     Ignore bogus ACPI info for offline CPUs
has been added to the -mm tree.  Its filename is
     ignore-bogus-acpi-info-for-offline-cpus.patch

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

------------------------------------------------------
Subject: Ignore bogus ACPI info for offline CPUs
From: Thomas Gleixner <[EMAIL PROTECTED]>

Booting a SMP kernel with maxcpus=1 on a SMP system leads to a hard hang,
because ACPI ignores the maxcpus setting and sends timer broadcast info for
the offline CPUs.  This results in a stuck for ever call to
smp_call_function_single() on an offline CPU.

Ignore the bogus information and print a kernel error to remind ACPI
folks to fix it.

Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---

 kernel/time/tick-broadcast.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff -puN kernel/time/tick-broadcast.c~ignore-bogus-acpi-info-for-offline-cpus 
kernel/time/tick-broadcast.c
--- a/kernel/time/tick-broadcast.c~ignore-bogus-acpi-info-for-offline-cpus
+++ a/kernel/time/tick-broadcast.c
@@ -243,11 +243,18 @@ void tick_broadcast_on_off(unsigned long
 {
        int cpu = get_cpu();
 
-       if (cpu == *oncpu)
-               tick_do_broadcast_on_off(&reason);
-       else
-               smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
-                                        &reason, 1, 1);
+       if (!cpu_isset(*oncpu, cpu_online_map)) {
+               printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
+                      "offline CPU #%d\n", *oncpu);
+       } else {
+
+               if (cpu == *oncpu)
+                       tick_do_broadcast_on_off(&reason);
+               else
+                       smp_call_function_single(*oncpu,
+                                                tick_do_broadcast_on_off,
+                                                &reason, 1, 1);
+       }
        put_cpu();
 }
 
_

Patches currently in -mm which might be from [EMAIL PROTECTED] are

ignore-bogus-acpi-info-for-offline-cpus.patch
drm-spinlock-initializer-cleanup.patch
s390-spinlock-initializer-cleanup.patch
i386-hpet-check-if-the-counter-works.patch
vsyscall-time-fix.patch

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