On Mon, Oct 17, 2022 at 9:56 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Mon, Oct 17, 2022 at 09:17:59AM -0700, Vishal Moola (Oracle) wrote: > > +++ b/mm/shmem.c > > @@ -932,21 +932,18 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, > > > > folio_batch_init(&fbatch); > > index = start; > > - while (index < end && find_lock_entries(mapping, index, end - 1, > > + while (index < end && find_lock_entries(mapping, &index, end - 1, > > Sorry for not spotting this in earlier revisions, but this is wrong. > Before, find_lock_entries() would go up to (end - 1) and then the > index++ at the end of the loop would increment index to "end", causing > the loop to terminate. Now we don't increment index any more, so the > condition is wrong. The condition is correct. Index maintains the exact same behavior. If a find_lock_entries() finds a folio, index is set to be directly after the last page in that folio, or simply incrementing for a value entry. The only time index is not changed at all is when find_lock_entries() finds no folios, which is the same as the original behavior as well. > I suggest just removing the 'index < end" half of the condition. I hadn't thought about it earlier but this index < end check seems unnecessary anyways. If index > end then find_lock_entries() shouldn't find any folios which would cause the loop to terminate. I could send an updated version getting rid of the "index < end" condition as well if you would like?
