On Wed, 24 Jan 2007 18:37:15 -0500 (EST)
Justin Piszcz <[email protected]> wrote:
> > Without digging too deeply, I'd say you've hit the same bug Sami Farin and
> > others
> > have reported starting with 2.6.19: pages mapped with kmap_atomic() become
> > unmapped
> > during memcpy() or similar operations. Try disabling preempt -- that seems to
> > be the
> > common factor.
> >
> >
> > -
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> >
> >
>
> After I run some other tests, I am going to re-run this test and see if it
> OOPSes again with PREEMPT off.
Strange. The below debug patch might catch it - please run with this
applied.
--- a/arch/i386/mm/highmem.c~kmap_atomic-debugging
+++ a/arch/i386/mm/highmem.c
@@ -30,7 +30,43 @@ void *kmap_atomic(struct page *page, enu
{
enum fixed_addresses idx;
unsigned long vaddr;
+ static unsigned warn_count = 10;
+ if (unlikely(warn_count == 0))
+ goto skip;
+
+ if (unlikely(in_interrupt())) {
+ if (in_irq()) {
+ if (type != KM_IRQ0 && type != KM_IRQ1 &&
+ type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
+ type != KM_BOUNCE_READ) {
+ WARN_ON(1);
+ warn_count--;
+ }
+ } else if (!irqs_disabled()) { /* softirq */
+ if (type != KM_IRQ0 && type != KM_IRQ1 &&
+ type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
+ type != KM_SKB_SUNRPC_DATA &&
+ type != KM_SKB_DATA_SOFTIRQ &&
+ type != KM_BOUNCE_READ) {
+ WARN_ON(1);
+ warn_count--;
+ }
+ }
+ }
+
+ if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ) {
+ if (!irqs_disabled()) {
+ WARN_ON(1);
+ warn_count--;
+ }
+ } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
+ if (irq_count() == 0 && !irqs_disabled()) {
+ WARN_ON(1);
+ warn_count--;
+ }
+ }
+skip:
/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
pagefault_disable();
if (!PageHighMem(page))
_
-
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