linux-kernel - [PATCH 4/7] mm/zswap: change dstmem size to one page

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Message-Id: <20231206-zswap-lock-optimize-v1-4-e25b059f9c3a@bytedance.com>
Date:   Wed, 06 Dec 2023 09:46:27 +0000
From:   Chengming Zhou <zhouchengming@...edance.com>
To:     Vitaly Wool <vitaly.wool@...sulko.com>,
        Nhat Pham <nphamcs@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Seth Jennings <sjenning@...hat.com>,
        Dan Streetman <ddstreet@...e.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Yosry Ahmed <yosryahmed@...gle.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Chengming Zhou <zhouchengming@...edance.com>
Subject: [PATCH 4/7] mm/zswap: change dstmem size to one page

Maybe I missed something, but the dstmem size of 2 * PAGE_SIZE is
very confusing, since we only need at most one page when compress,
and the "dlen" is also PAGE_SIZE in acomp_request_set_params().

So change it to one page, and fix the comments.

Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
---
 mm/zswap.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index d93a7b58b5af..999671dcb469 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -699,7 +699,7 @@ static int zswap_dstmem_prepare(unsigned int cpu)
 	struct mutex *mutex;
 	u8 *dst;
 
-	dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+	dst = kmalloc_node(PAGE_SIZE, GFP_KERNEL, cpu_to_node(cpu));
 	if (!dst)
 		return -ENOMEM;
 
@@ -1649,8 +1649,7 @@ bool zswap_store(struct folio *folio)
 	sg_init_table(&input, 1);
 	sg_set_page(&input, page, PAGE_SIZE, 0);
 
-	/* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
-	sg_init_one(&output, dst, PAGE_SIZE * 2);
+	sg_init_one(&output, dst, PAGE_SIZE);
 	acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);
 	/*
 	 * it maybe looks a little bit silly that we send an asynchronous request,

-- 
b4 0.10.1