From: Andrew Morton This is almost certainly wrong. Or at least incomplete. Cc: Ingo Molnar Signed-off-by: Andrew Morton --- arch/i386/mm/highmem.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff -puN arch/i386/mm/highmem.c~kmap_atomic-debugging arch/i386/mm/highmem.c --- a/arch/i386/mm/highmem.c~kmap_atomic-debugging +++ a/arch/i386/mm/highmem.c @@ -30,7 +30,38 @@ 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) { + WARN_ON(1); + warn_count--; + } + } else { /* softirq */ + if (type != KM_IRQ0 && type != KM_IRQ1 && + type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1) { + WARN_ON(1); + warn_count--; + } + } + } + + if (type == KM_IRQ0 || type == KM_IRQ1) { + if (!irqs_disabled() && !hardirq_count()) { + 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)) _