From: Ingo Molnar Date: Fri, 20 Feb 2009 16:44:21 +0000 (+0100) Subject: x86, pat: add large-PAT check to split_large_page() X-Git-Tag: v2.6.30-rc1~211^2~43^5~16 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7a5714e0186030676d79a7b4b9830c8e45c3b0a1;p=pandora-kernel.git x86, pat: add large-PAT check to split_large_page() Impact: future-proof the split_large_page() function Linus noticed that split_large_page() is not safe wrt. the PAT bit: it is bit 12 on the 1GB and 2MB page table level (_PAGE_BIT_PAT_LARGE), and it is bit 7 on the 4K page table level (_PAGE_BIT_PAT). Currently it is not a problem because we never set _PAGE_BIT_PAT_LARGE on any of the large-page mappings - but should this happen in the future the split_large_page() would silently lift bit 12 into the lowlevel 4K pte and would start corrupting the physical page frame offset. Not fun. So add a debug warning, to make sure if something ever sets the PAT bit then this function gets updated too. Cc: Linus Torvalds Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed