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Subject[21/82] x86, kdump: Change copy_oldmem_page() to use cached addressing
2.6.35-stable review patch.  If anyone has any objections, please let us know.


From: Cliff Wickman <>

commit 37a2f9f30a360fb03522d15c85c78265ccd80287 upstream.

The copy of /proc/vmcore to a user buffer proceeds much faster
if the kernel addresses memory as cached.

With this patch we have seen an increase in transfer rate from
less than 15MB/s to 80-460MB/s, depending on size of the
transfer. This makes a big difference in time needed to save a
system dump.

Signed-off-by: Cliff Wickman <>
Acked-by: "Eric W. Biederman" <>
LKML-Reference: <>
Signed-off-by: Ingo Molnar <>
Signed-off-by: Greg Kroah-Hartman <>

arch/x86/kernel/crash_dump_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -34,7 +34,7 @@ ssize_t copy_oldmem_page(unsigned long p
if (!csize)
return 0;

- vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
+ vaddr = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
if (!vaddr)
return -ENOMEM;

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