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?
--- 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) {
