Marcelo,
This patch fixes a problem with excessive stack usage in
arch/i386/kernel/nmi.c:check_nmi_watchdog(). It's a backport
of a fix that has been in the 2.5 kernel for quite a while.
There are no behavioural changes.
The problem is that the code copies NR_CPUS irq_cpustat_t values
to the stack, even though only NR_CPUS ints actually are needed.
irq_cpustat_t values are 24 bytes large, but they are also
____cacheline_aligned, which makes them blow up to 128 bytes
on P4s. That's 128*32 == 4 kilobytes of stack on a P4 SMP kernel,
when 4*32 == 128 bytes suffices.
/Mikael
diff -ruN linux-2.4.21-pre1/arch/i386/kernel/nmi.c linux-2.4.21-pre1.check_nmi/arch/i386/kernel/nmi.c
--- linux-2.4.21-pre1/arch/i386/kernel/nmi.c 2002-08-07 00:52:18.000000000 +0200
+++ linux-2.4.21-pre1.check_nmi/arch/i386/kernel/nmi.c 2002-12-12 14:19:10.000000000 +0100
@@ -72,18 +72,21 @@
int __init check_nmi_watchdog (void)
{
- irq_cpustat_t tmp[NR_CPUS];
+ unsigned int prev_nmi_count[NR_CPUS];
int j, cpu;
printk(KERN_INFO "testing NMI watchdog ... ");
- memcpy(tmp, irq_stat, sizeof(tmp));
+ for (j = 0; j < smp_num_cpus; j++) {
+ cpu = cpu_logical_map(j);
+ prev_nmi_count[cpu] = irq_stat[cpu].__nmi_count;
+ }
sti();
mdelay((10*1000)/nmi_hz); // wait 10 ticks
for (j = 0; j < smp_num_cpus; j++) {
cpu = cpu_logical_map(j);
- if (nmi_count(cpu) - tmp[cpu].__nmi_count <= 5) {
+ if (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {
printk("CPU#%d: NMI appears to be stuck!\n", cpu);
return -1;
}
-
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This archive was generated by hypermail 2b29 : Sun Dec 15 2002 - 22:00:24 EST