On Thu, Jul 31, 2014 at 06:43:25PM -0400, Peter Feiner wrote: > 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 <pfeiner@xxxxxxxxxx> Acked-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>