From: SeongJae Park <sj@kernel.org>
Date: Wed, 27 Aug 2025 20:18:38 +0000 (-0700)
Subject: mm/zswap: cleanup incompressible pages handling code
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=faa91e516bce67de75a48aa9bf2138c37037b1b0;p=users%2Fjedix%2Flinux-maple.git

mm/zswap: cleanup incompressible pages handling code

Following Chris Li's suggestions [1], make the code easier to read and
manage.

Link: https://lkml.kernel.org/r/20250828163913.57957-1-sj@kernel.org
Kink: https://lore.kernel.org/CACePvbWGPApYr7G29FzbmWzRw-BJE39WH7kUHSaHs+Lnw8=-qQ@mail.gmail.com [1]
Signed-off-by: SeongJae Park <sj@kernel.org>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Takero Funaki <flintglass@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/zswap.c b/mm/zswap.c
index 0ec239aae9bc..0c8dd8876d8e 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -952,6 +952,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 	struct zpool *zpool;
 	gfp_t gfp;
 	u8 *dst;
+	bool mapped = false;
 
 	acomp_ctx = acomp_ctx_get_cpu_lock(pool);
 	dst = acomp_ctx->buffer;
@@ -988,9 +989,8 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 	 * only adds metadata overhead.  swap_writeout() will put the page back
 	 * to the active LRU list in the case.
 	 */
-	if (comp_ret || !dlen)
+	if (comp_ret || !dlen || dlen >= PAGE_SIZE) {
 		dlen = PAGE_SIZE;
-	if (dlen >= PAGE_SIZE) {
 		if (!mem_cgroup_zswap_writeback_enabled(
 					folio_memcg(page_folio(page)))) {
 			comp_ret = comp_ret ? comp_ret : -EINVAL;
@@ -999,6 +999,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 		comp_ret = 0;
 		dlen = PAGE_SIZE;
 		dst = kmap_local_page(page);
+		mapped = true;
 	}
 
 	zpool = pool->zpool;
@@ -1012,7 +1013,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 	entry->length = dlen;
 
 unlock:
-	if (dst != acomp_ctx->buffer)
+	if (mapped)
 		kunmap_local(dst);
 	if (comp_ret == -ENOSPC || alloc_ret == -ENOSPC)
 		zswap_reject_compress_poor++;
@@ -1030,7 +1031,7 @@ static bool zswap_decompress(struct zswap_entry *entry, struct folio *folio)
 	struct zpool *zpool = entry->pool->zpool;
 	struct scatterlist input, output;
 	struct crypto_acomp_ctx *acomp_ctx;
-	int decomp_ret, dlen;
+	int decomp_ret = 0, dlen = PAGE_SIZE;
 	u8 *src, *obj;
 
 	acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool);
@@ -1039,9 +1040,7 @@ static bool zswap_decompress(struct zswap_entry *entry, struct folio *folio)
 	/* zswap entries of length PAGE_SIZE are not compressed. */
 	if (entry->length == PAGE_SIZE) {
 		memcpy_to_folio(folio, 0, obj, entry->length);
-		zpool_obj_read_end(zpool, entry->handle, obj);
-		acomp_ctx_put_unlock(acomp_ctx);
-		return true;
+		goto read_done;
 	}
 
 	/*
@@ -1064,6 +1063,7 @@ static bool zswap_decompress(struct zswap_entry *entry, struct folio *folio)
 	decomp_ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
 	dlen = acomp_ctx->req->dlen;
 
+read_done:
 	zpool_obj_read_end(zpool, entry->handle, obj);
 	acomp_ctx_put_unlock(acomp_ctx);