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authorWill Deacon <will.deacon@arm.com>2011-05-19 13:21:14 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-05-26 10:23:24 +0100
commit7b7bf499f79de3f6c85a340c8453a78789523f85 (patch)
tree1d0bf7ae8d5befe135fb7e7cfc455656a0ec7b34 /arch/arm/include/asm/page.h
parent4db70f73e56961b9bcdfd0c36c62847a18b7dbb5 (diff)
ARM: 6913/1: sparsemem: allow pfn_valid to be overridden when using SPARSEMEM
In commit eb33575c ("[ARM] Double check memmap is actually valid with a memmap has unexpected holes V2"), a new function, memmap_valid_within, was introduced to mmzone.h so that holes in the memmap which pass pfn_valid in SPARSEMEM configurations can be detected and avoided. The fix to this problem checks that the pfn <-> page linkages are correct by calculating the page for the pfn and then checking that page_to_pfn on that page returns the original pfn. Unfortunately, in SPARSEMEM configurations, this results in reading from the page flags to determine the correct section. Since the memmap here has been freed, junk is read from memory and the check is no longer robust. In the best case, reading from /proc/pagetypeinfo will give you the wrong answer. In the worst case, you get SEGVs, Kernel OOPses and hung CPUs. Furthermore, ioremap implementations that use pfn_valid to disallow the remapping of normal memory will break. This patch allows architectures to provide their own pfn_valid function instead of using the default implementation used by sparsemem. The architecture-specific version is aware of the memmap state and will return false when passed a pfn for a freed page within a valid section. Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Tested-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm/page.h')
-rw-r--r--arch/arm/include/asm/page.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
index f51a69595f6..ac75d084888 100644
--- a/arch/arm/include/asm/page.h
+++ b/arch/arm/include/asm/page.h
@@ -197,7 +197,7 @@ typedef unsigned long pgprot_t;
typedef struct page *pgtable_t;
-#ifndef CONFIG_SPARSEMEM
+#ifdef CONFIG_HAVE_ARCH_PFN_VALID
extern int pfn_valid(unsigned long);
#endif