From: Mel Gorman Date: Thu, 2 Oct 2014 18:47:41 +0000 (+0100) Subject: mm: migrate: Close race between migration completion and mprotect X-Git-Tag: fixes-for-v3.18-merge-window~51^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d3cb8bf6081b8b7a2dabb1264fe968fd870fa595;p=pandora-kernel.git mm: migrate: Close race between migration completion and mprotect A migration entry is marked as write if pte_write was true at the time the entry was created. The VMA protections are not double checked when migration entries are being removed as mprotect marks write-migration-entries as read. It means that potentially we take a spurious fault to mark PTEs write again but it's straight-forward. However, there is a race between write migrations being marked read and migrations finishing. This potentially allows a PTE to be write that should have been read. Close this race by double checking the VMA permissions using maybe_mkwrite when migration completes. [torvalds@linux-foundation.org: use maybe_mkwrite] Cc: stable@vger.kernel.org Signed-off-by: Mel Gorman Acked-by: Rik van Riel Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed