On Sat, May 02, 2020 at 01:29:11PM +0000, Wei Yang wrote: >On Fri, May 01, 2020 at 03:48:53PM -0700, Andrew Morton wrote: >>On Fri, 1 May 2020 01:52:59 +0000 Wei Yang <richard.weiyang@xxxxxxxxx> wrote: >> >>> When the condition is true, there are two possibilities: >> >>I'm struggling with this one. >> >>> 1. count == SWAP_MAP_BAD >>> 2. count == (SWAP_MAP_MAX & COUNT_CONTINUED) == SWAP_MAP_SHMEM >> >>I'm not sure what 2. is trying to say. For a start, (SWAP_MAP_MAX & >>COUNT_CONTINUED) is zero. I guess it meant "|"? > >Oops, you are right. It should be (SWAP_MAP_MAX | COUNT_CONTINUED). > >Sorry for the confusion. > Hmm... I made a mistake again, the two cases should be * SWAP_MAP_BAD * (SWAP_MAP_BAD | COUNT_CONTINUED) == SWAP_MAP_SHMEM What a shame. >> >>Also, the return value documentation says we return EINVAL for migration >>entries. Where's that happening, or is the comment out of date? >> > >Not paid attention to this. > >Take look into the code, I don't find a relationship between the swap count >and migration. Seems we just make a migration entry but not duplicate it. >If my understanding is correct. > >>> The first case would be filtered by the first if in __swap_duplicate(). >>> >>> And the second case means this swap entry is for shmem. Since we never >>> do another duplication for shmem swap entry. This won't happen neither. >> > >-- >Wei Yang >Help you, Help me -- Wei Yang Help you, Help me
