On Sun, Oct 18, 2015 at 10:05:28PM -0700, Hugh Dickins wrote: > Hitherto page migration has avoided using a migration entry for a > swapcache page mapped into userspace, apparently for historical reasons. > So any page blessed with swapcache would entail a minor fault when it's > next touched, which page migration otherwise tries to avoid. Swapcache > in an mlocked area is rare, so won't often matter, but still better fixed. > > Just rearrange the block in try_to_unmap_one(), to handle TTU_MIGRATION > before checking PageAnon, that's all (apart from some reindenting). > > Well, no, that's not quite all: doesn't this by the way fix a soft_dirty > bug, that page migration of a file page was forgetting to transfer the > soft_dirty bit? Probably not a serious bug: if I understand correctly, > soft_dirty afficionados usually have to handle file pages separately > anyway; but we publish the bit in /proc/<pid>/pagemap on file mappings > as well as anonymous, so page migration ought not to perturb it. > > Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Sorry for delay in response. Indeed this should fix the nit, thanks! Reviewed-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>