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authorRusty Russell <rusty@rustcorp.com.au>2009-04-21 16:00:15 +0930
committerIngo Molnar <mingo@elte.hu>2009-04-21 10:09:49 +0200
commit2f537a9f8e82f55c241b002c8cfbf34303b45ada (patch)
tree121f8b9a4053c8316b7e4bcc52c78b257c768c9b
parent06c38d5e36b12d040839ff224e805146c0368556 (diff)
x86: fix boot crash in NMI watchdog with CONFIG_CPUMASK_OFFSTACK=y and flat APIC
fcef8576d8a64fc603e719c97d423f9f6d4e0e8b converted backtrace_mask to a cpumask_var_t, and assumed check_nmi_watchdog was called before nmi_watchdog_tick was ever called. Steven's oops shows I was wrong. This is something of a bandaid: I'm not sure we *should* be calling nmi_watchdog_tick before check_nmi_watchdog. Note that gcc eliminates this test for the CONFIG_CPUMASK_OFFSTACK=n case. [ Impact: fix boot crash in rare configs ] Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> LKML-Reference: <alpine.DEB.2.00.0904202113520.10097@gandalf.stny.rr.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/kernel/apic/nmi.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c
index d6bd6240715..2ba52f35a88 100644
--- a/arch/x86/kernel/apic/nmi.c
+++ b/arch/x86/kernel/apic/nmi.c
@@ -414,7 +414,8 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
touched = 1;
}
- if (cpumask_test_cpu(cpu, backtrace_mask)) {
+ /* We can be called before check_nmi_watchdog, hence NULL check. */
+ if (backtrace_mask != NULL && cpumask_test_cpu(cpu, backtrace_mask)) {
static DEFINE_SPINLOCK(lock); /* Serialise the printks */
spin_lock(&lock);