From 13f96d8f4c5a3f6a6b5e578d08869d79d690e0b2 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Tue, 1 Sep 2009 22:01:27 +0100 Subject: ARM: 5687/1: fix an oops with highmem In xdr_partial_copy_from_skb() there is that sequence: kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA); [...] flush_dcache_page(*ppage); kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA); Mixing flush_dcache_page() and kmap_atomic() is a bit odd, especially since kunmap_atomic() must deal with cache issues already. OTOH the non-highmem case must use flush_dcache_page() as kunmap_atomic() becomes a no op with no cache maintenance. Problem is that with highmem the implementation of kmap_atomic() doesn't set page->virtual, and page_address(page) returns 0 in that case. Here flush_dcache_page() calls __flush_dcache_page() which calls __cpuc_flush_dcache_page(page_address(page)) resulting in a kernel oops. None of the kmap_atomic() implementations uses set_page_address(). Hence we can assume page_address() is always expected to return 0 in that case. Let's conditionally call __cpuc_flush_dcache_page() only when the page address is non zero, and perform that test only when highmem is configured. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King --- arch/arm/mm/flush.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'arch/arm') diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index c07222eb5ce..575f3ad722e 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -144,7 +144,14 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page) * page. This ensures that data in the physical page is mutually * coherent with the kernels mapping. */ - __cpuc_flush_dcache_page(page_address(page)); +#ifdef CONFIG_HIGHMEM + /* + * kmap_atomic() doesn't set the page virtual address, and + * kunmap_atomic() takes care of cache flushing already. + */ + if (page_address(page)) +#endif + __cpuc_flush_dcache_page(page_address(page)); /* * If this is a page cache page, and we have an aliasing VIPT cache, -- cgit v1.2.3