From: Will Deacon Date: Fri, 10 Aug 2012 16:51:18 +0000 (+0100) Subject: ARM: 7487/1: mm: avoid setting nG bit for user mappings that aren't present X-Git-Tag: v3.2.30~53 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed756add374b0742f00fae8ff74db2e0186c0c70;p=pandora-kernel.git ARM: 7487/1: mm: avoid setting nG bit for user mappings that aren't present commit 47f1204329237a0f8655f5a9f14a38ac81946ca1 upstream. Swap entries are encoding in ptes such that !pte_present(pte) and pte_file(pte). The remaining bits of the descriptor are used to identify the swapfile and offset within it to the swap entry. When writing such a pte for a user virtual address, set_pte_at unconditionally sets the nG bit, which (in the case of LPAE) will corrupt the swapfile offset and lead to a BUG: [ 140.494067] swap_free: Unused swap offset entry 000763b4 [ 140.509989] BUG: Bad page map in process rs:main Q:Reg pte:0ec76800 pmd:8f92e003 This patch fixes the problem by only setting the nG bit for user mappings that are actually present. Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed