Avoid false positive warnings in kmap_atomic_prot() with DEBUG_HIGHMEM
Andrew Morton [Fri, 28 Mar 2008 18:47:34 +0000 (11:47 -0700)]
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 <pstaszewski@artcom.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Christoph Lameter <clameter@sgi.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 [ 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 <torvalds@linux-foundation.org>

arch/x86/mm/highmem_32.c

index 3d936f2..9cf33d3 100644 (file)
@@ -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)));