On Thu, Dec 14, 2023 at 2:23 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Wed, 13 Dec 2023 17:02:25 -0800 Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote:
>
> > On Tue, Dec 12, 2023 at 8:18 PM Chengming Zhou
> > <zhouchengming@xxxxxxxxxxxxx> wrote:
> > >
> > > Also after the common decompress part goes to __zswap_load(), we can
> > > cleanup the zswap_reclaim_entry() a little.
> >
> > I think you mean zswap_writeback_entry(), same for the commit title.
>
> I updated my copy of the changelog, thanks.
>
> > > - /*
> > > - * If we get here because the page is already in swapcache, a
> > > - * load may be happening concurrently. It is safe and okay to
> > > - * not free the entry. It is also okay to return !0.
> > > - */
> >
> > This comment should be moved above the failure check of
> > __read_swap_cache_async() above, not completely removed.
>
> This?
Yes, thanks a lot. Although I think a new version is needed anyway to
address other comments.
>
> --- a/mm/zswap.c~mm-zswap-cleanup-zswap_reclaim_entry-fix
> +++ a/mm/zswap.c
> @@ -1457,8 +1457,14 @@ static int zswap_writeback_entry(struct
> mpol = get_task_policy(current);
> page = __read_swap_cache_async(swpentry, GFP_KERNEL, mpol,
> NO_INTERLEAVE_INDEX, &page_was_allocated, true);
> - if (!page)
> + if (!page) {
> + /*
> + * If we get here because the page is already in swapcache, a
> + * load may be happening concurrently. It is safe and okay to
> + * not free the entry. It is also okay to return !0.
> + */
> return -ENOMEM;
> + }
>
> /* Found an existing page, we raced with load/swapin */
> if (!page_was_allocated) {
>
