Avoid false positive warnings in kmap_atomic_prot() with DEBUG_HIGHMEM

I believe http://bugzilla.kernel.org/show_bug.cgi?id=10318 is a false
positive.  There's no way in which networking will be using highmem pages
here, so it won't be taking the KM_USER0 kmap slot, so there's no point in
performing these checks.

Cc: Pawel Staszewski <[email protected]>
Cc: Ingo Molnar <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Cc: "David S. Miller" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
 [ Really sad.  We lose almost all real-life coverage of the debug tests
   with this patch. Now it will only report problems for the cases where
   people actually end up using a HIGHMEM page, not when they just _might_
   use one.    - Linus ]
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index 3d936f23270409344105faf23b37ce45b0e02535..9cf33d3ee5bc7ee0d10fbc4b0ce9c9fc04697ee8 100644 (file)
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -73,15 +73,15 @@ void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
 {
        enum fixed_addresses idx;
        unsigned long vaddr;
-       /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
-
-       debug_kmap_atomic_prot(type);
 
+       /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
        pagefault_disable();
 
        if (!PageHighMem(page))
                return page_address(page);
 
+       debug_kmap_atomic_prot(type);
+
        idx = type + KM_TYPE_NR*smp_processor_id();
        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
        BUG_ON(!pte_none(*(kmap_pte-idx)));