On 07/27/2013 12:55 AM, Andy Lutomirski wrote: > On Fri, Jul 26, 2013 at 1:18 PM, Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote: >> Andy reported that if file page get reclaimed we loose soft-dirty bit >> if it was there, so save _PAGE_BIT_SOFT_DIRTY bit when page address >> get encoded into pte entry. Thus when #pf happens on such non-present >> pte we can restore it back. >> > > Unless I'm misunderstanding this, it's saving the bit in the > non-present PTE. This sounds wrong -- what happens if the entire pmd > (or whatever the next level is called) gets zapped? (Also, what > happens if you unmap a file and map a different file there?) The whole pte gets zapped on vma unmap, and in this case forgetting the soft-dirty bit completely is OK. > --Andy > . > -- 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>