On Tue, 2017-04-25 at 14:37 -0700, Andrew Morton wrote: > On Fri, 21 Apr 2017 20:47:39 +0800 "Huang, Ying" <ying.huang@xxxxxxxxx> wrote: > > > > > From: Huang Ying <ying.huang@xxxxxxxxx> > > > > In swapcache_free_entries(), if swap_info_get_cont() return NULL, > > something wrong occurs for the swap entry. But we should still > > continue to free the following swap entries in the array instead of > > skip them to avoid swap space leak. This is just problem in error > > path, where system may be in an inconsistent state, but it is still > > good to fix it. > > > > ... > > > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -1079,8 +1079,6 @@ void swapcache_free_entries(swp_entry_t *entries, int n) > > p = swap_info_get_cont(entries[i], prev); > > if (p) > > swap_entry_free(p, entries[i]); > > - else > > - break; > > prev = p; > So now prev==NULL. Will this code get the locking correct in > swap_info_get_cont()? I think so, but please double-check. > There are 4 possible cases, and I checked that the logic in swap_info_get_cont do the expected: entries[i] valid? prev Expected swap_info_get_cont behavior --------------------------------------------------------------------- NO NULL Return NULL p, Do nothing on lock/unlock NO NON-NULL Return NULL p, Unlock prev YES NULL Return non-NULL p, lock p YES NON-NULL Return non-NULL p, (p != prev) unlock prev and lock p (p == prev) do nothing on lock/unlock Thanks. Tim > -- 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>
