On 07/24/2013 08:08 PM, Cyrill Gorcunov wrote: > Andy Lutomirski reported that in case if a page with _PAGE_SOFT_DIRTY > bit set get swapped out, the bit is getting lost and no longer > available when pte read back. > > To resolve this we introduce _PTE_SWP_SOFT_DIRTY bit which is > saved in pte entry for the page being swapped out. When such page > is to be read back from a swap cache we check for bit presence > and if it's there we clear it and restore the former _PAGE_SOFT_DIRTY > bit back. > > One of the problem was to find a place in pte entry where we can > save the _PTE_SWP_SOFT_DIRTY bit while page is in swap. The > _PAGE_PSE was chosen for that, it doesn't intersect with swap > entry format stored in pte. > > Reported-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx> > Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> > Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Matt Mackall <mpm@xxxxxxxxxxx> > Cc: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx> > Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx> > Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Acked-by: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> -- 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>