From nobody Sat Dec 27 03:42:51 2025 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1108D53E12 for ; Tue, 26 Dec 2023 15:55:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=bytedance.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou Date: Tue, 26 Dec 2023 15:54:12 +0000 Subject: [PATCH v4 5/6] mm/zswap: cleanup zswap_writeback_entry() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20231213-zswap-dstmem-v4-5-f228b059dd89@bytedance.com> References: <20231213-zswap-dstmem-v4-0-f228b059dd89@bytedance.com> In-Reply-To: <20231213-zswap-dstmem-v4-0-f228b059dd89@bytedance.com> To: Andrew Morton , Seth Jennings , Johannes Weiner , Vitaly Wool , Nhat Pham , Chris Li , Yosry Ahmed , Dan Streetman Cc: linux-kernel@vger.kernel.org, Chengming Zhou , linux-mm@kvack.org, Nhat Pham , Yosry Ahmed , Chris Li X-Developer-Signature: v=1; a=ed25519-sha256; t=1703606082; l=2338; i=zhouchengming@bytedance.com; s=20231204; h=from:subject:message-id; bh=tAV69Q+4us6Py1b2R2r8p5EYfYNSenhTMFhuOp7vNNQ=; b=afViGCtigOHtj8SqyE1/3tYO10W9zGnBEqlNj/WHy0NkwORwH+k6pwR/NJpbIHP3TQeqORo2h ERJwMflduKtC/okQR5pR1LwHwhvGLXlCdgX/gX53ZckJzqrZB76ELZ2 X-Developer-Key: i=zhouchengming@bytedance.com; a=ed25519; pk=xFTmRtMG3vELGJBUiml7OYNdM393WOMv0iWWeQEVVdA= X-Migadu-Flow: FLOW_OUT Also after the common decompress part goes to __zswap_load(), we can cleanup the zswap_writeback_entry() a little. Reviewed-by: Yosry Ahmed Reviewed-by: Nhat Pham Acked-by: Chris Li (Google) Signed-off-by: Chengming Zhou --- mm/zswap.c | 29 ++++++++++------------------- 1 file changed, 10 insertions(+), 19 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index 86886276cb81..40ee9f109f98 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1443,7 +1443,6 @@ static int zswap_writeback_entry(struct zswap_entry *= entry, struct page *page; struct mempolicy *mpol; bool page_was_allocated; - int ret; struct writeback_control wbc =3D { .sync_mode =3D WB_SYNC_NONE, }; @@ -1452,16 +1451,17 @@ static int zswap_writeback_entry(struct zswap_entry= *entry, mpol =3D get_task_policy(current); page =3D __read_swap_cache_async(swpentry, GFP_KERNEL, mpol, NO_INTERLEAVE_INDEX, &page_was_allocated, true); - if (!page) { - ret =3D -ENOMEM; - goto fail; - } + if (!page) + return -ENOMEM; =20 - /* 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 =3D -EEXIST; - goto fail; + return -EEXIST; } =20 /* @@ -1475,8 +1475,7 @@ static int zswap_writeback_entry(struct zswap_entry *= entry, if (zswap_rb_search(&tree->rbroot, swp_offset(entry->swpentry)) !=3D entr= y) { spin_unlock(&tree->lock); delete_from_swap_cache(page_folio(page)); - ret =3D -ENOMEM; - goto fail; + return -ENOMEM; } spin_unlock(&tree->lock); =20 @@ -1497,15 +1496,7 @@ static int zswap_writeback_entry(struct zswap_entry = *entry, __swap_writepage(page, &wbc); put_page(page); =20 - 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; } =20 static int zswap_is_page_same_filled(void *ptr, unsigned long *value) --=20 b4 0.10.1