From: Peter Feiner Date: Wed, 6 Aug 2014 23:08:09 +0000 (-0700) Subject: mm: softdirty: respect VM_SOFTDIRTY in PTE holes X-Git-Tag: omap-for-v3.17/fixes-against-rc2~137^2~93 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=68b5a652485682f67eacdee3deae640fb7845b63;p=pandora-kernel.git mm: softdirty: respect VM_SOFTDIRTY in PTE holes After a VMA is created with the VM_SOFTDIRTY flag set, /proc/pid/pagemap should report that the VMA's virtual pages are soft-dirty until VM_SOFTDIRTY is cleared (i.e., by the next write of "4" to /proc/pid/clear_refs). However, pagemap ignores the VM_SOFTDIRTY flag for virtual addresses that fall in PTE holes (i.e., virtual addresses that don't have a PMD, PUD, or PGD allocated yet). To observe this bug, use mmap to create a VMA large enough such that there's a good chance that the VMA will occupy an unused PMD, then test the soft-dirty bit on its pages. In practice, I found that a VMA that covered a PMD's worth of address space was big enough. This patch adds the necessary VMA lookup to the PTE hole callback in /proc/pid/pagemap's page walk and sets soft-dirty according to the VMAs' VM_SOFTDIRTY flag. Signed-off-by: Peter Feiner Acked-by: Cyrill Gorcunov Cc: Pavel Emelyanov Cc: Hugh Dickins Acked-by: Naoya Horiguchi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed