The patch titled
Subject: mm/zswap: cleanup zswap_writeback_entry()
has been added to the -mm mm-unstable branch. Its filename is
mm-zswap-cleanup-zswap_writeback_entry.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-cleanup-zswap_writeback_entry.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Subject: mm/zswap: cleanup zswap_writeback_entry()
Date: Tue, 26 Dec 2023 15:54:12 +0000
Also after the common decompress part goes to __zswap_load(), we can
cleanup the zswap_writeback_entry() a little.
Link: https://lkml.kernel.org/r/20231213-zswap-dstmem-v4-5-f228b059dd89@xxxxxxxxxxxxx
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Reviewed-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
Acked-by: Chris Li <chrisl@xxxxxxxxxx> (Google)
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Seth Jennings <sjenning@xxxxxxxxxx>
Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 29 ++++++++++-------------------
1 file changed, 10 insertions(+), 19 deletions(-)
--- a/mm/zswap.c~mm-zswap-cleanup-zswap_writeback_entry
+++ a/mm/zswap.c
@@ -1443,7 +1443,6 @@ static int zswap_writeback_entry(struct
struct page *page;
struct mempolicy *mpol;
bool page_was_allocated;
- int ret;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
@@ -1452,16 +1451,17 @@ 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) {
- ret = -ENOMEM;
- goto fail;
- }
+ if (!page)
+ return -ENOMEM;
- /* Found an existing page, we raced with load/swapin */
+ /*
+ * Found an existing page, we raced with load/swapin. We generally
+ * writeback cold pages from zswap, and swapin means the page just
+ * became hot. Skip this page and let the caller find another one.
+ */
if (!page_was_allocated) {
put_page(page);
- ret = -EEXIST;
- goto fail;
+ return -EEXIST;
}
/*
@@ -1475,8 +1475,7 @@ static int zswap_writeback_entry(struct
if (zswap_rb_search(&tree->rbroot, swp_offset(entry->swpentry)) != entry) {
spin_unlock(&tree->lock);
delete_from_swap_cache(page_folio(page));
- ret = -ENOMEM;
- goto fail;
+ return -ENOMEM;
}
spin_unlock(&tree->lock);
@@ -1492,15 +1491,7 @@ static int zswap_writeback_entry(struct
__swap_writepage(page, &wbc);
put_page(page);
- return ret;
-
-fail:
- /*
- * 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 ret;
+ return 0;
}
static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
_
Patches currently in -mm which might be from zhouchengming@xxxxxxxxxxxxx are
mm-zswap-change-dstmem-size-to-one-page.patch
mm-zswap-reuse-dstmem-when-decompress.patch
mm-zswap-refactor-out-__zswap_load.patch
mm-zswap-cleanup-zswap_load.patch
mm-zswap-cleanup-zswap_writeback_entry.patch
mm-zswap-change-per-cpu-mutex-and-buffer-to-per-acomp_ctx.patch
