On Tue, 23 Oct 2001, Tony Dziedzic wrote:
|>This patch address a BUG in highmem.h that LKCD triggers when dumping to
|>a large memory system with HIGHMEM_DEBUG enabled. The BUG occurs the
|>second time dump_add_page is called for a high memory page, when
|>dump_add_page calls kmap_atomic. If HIGHMEM_DEBUG is enabled
|>kmap_atomic verifies that the caller has released the temporary mapping
|>via a call to kunmap_atomic. Since this hasn't happened, highmem.h
|>BUGs.
|>
|>The patch adds a call to kunmap_atomic at the end of dump_add_page.
|>Note that the patch is not required unless your kernel has HIGHMEM_DEBUG
|>enabled. There is a slight performance hit associated with this patch
|>(due to kunmap_atomic's TLB flush). Those who object to the performance
|>hit may choose to enclose the #ifdef CONFIG_HIGHMEM conditional in a
|>#ifdef HIGHMEM_DEBUG conditional.
|>
|>FYI,
|>Tony Dziedzic
|>Storigen Systems, Inc.
Checked in.
--Matt
|