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| author | Rusty Russell <rusty@rustcorp.com.au> | 2009-04-21 08:30:15 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-04-21 10:09:49 +0200 |
| commit | 2f537a9f8e82f55c241b002c8cfbf34303b45ada (patch) | |
| tree | 121f8b9a4053c8316b7e4bcc52c78b257c768c9b /arch | |
| parent | x86-64: fix FPU corruption with signals and preemption (diff) | |
| download | linux-2f537a9f8e82f55c241b002c8cfbf34303b45ada.tar.xz linux-2f537a9f8e82f55c241b002c8cfbf34303b45ada.zip | |
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/apic/nmi.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c index d6bd62407152..2ba52f35a88c 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); |