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authorRussell King <rmk+kernel@arm.linux.org.uk>2009-10-25 11:23:04 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-12-01 19:20:07 +0100
commit421fe93cc4b06b2f5e875cbe0f692800d4862ee5 (patch)
tree88c5985799273a7c854159246d715e1ad85646f9 /arch/arm/mm/fault-armv.c
parentARM: Avoid evaluating page_address() multiple times (diff)
downloadlinux-421fe93cc4b06b2f5e875cbe0f692800d4862ee5.tar.xz
linux-421fe93cc4b06b2f5e875cbe0f692800d4862ee5.zip
ARM: ZERO_PAGE: Avoid flush_dcache_page() for zero page
The zero page is read-only, and has its cache state cleared during boot. No further maintanence for this page is required. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm/fault-armv.c')
-rw-r--r--arch/arm/mm/fault-armv.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index d0d17b6a3703..4fbc7de8b4ac 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -151,7 +151,14 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
if (!pfn_valid(pfn))
return;
+ /*
+ * The zero page is never written to, so never has any dirty
+ * cache lines, and therefore never needs to be flushed.
+ */
page = pfn_to_page(pfn);
+ if (page == ZERO_PAGE(0))
+ return;
+
mapping = page_mapping(page);
#ifndef CONFIG_SMP
if (test_and_clear_bit(PG_dcache_dirty, &page->flags))