From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.203 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794203796; b=fjAqbZl2iBNsVcfv505O3a+Iyl/tbvDxsPVKKvj/fAUQhKU5eZeKi/hYP43CGd6kUZ1i q92o7LkROCRnPBt3EhPpD3Jt5oAJIxABhkaHAP1dGW9o4yluP2NmyQzf3J2cvDflc+G7L 7RVCtHzL20QBj9a1HGUlLPCsdcyj7M12pdEwJYO31dJHS+7mEV1G8Gog68Ru9U9S9YT/d OaigwvRrvWyP/X8ND5NWEJsoGd0C0pzddOmV7s37YR4uxPSprSf/fj2ziAHQI5oj5IxPO YHN8+7U0kCu6l6a2ODytzb4yZ9RM8G9ZTPtl2LWSFxZWTRtKKderwfHYP1A0+SjB96Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794203796; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version:Content-type: Content-Transfer-Encoding; bh=2Ad8L18vWEsLzi69aph4uH3QAUHZEIhwmqVh/GCy+bM=; b=yJ3/5MtFLTxa3aswaDepY2cTaHyQuD2lKd2wcIzRpWc5XIDO3v45MyIJjTX1K5i2ashv 9ylzXLqF3V2uP3C/cu1hZ9oA3h4p27CKWg3SAEkei8QAi+5BGnWmHxujg1DEalBzs2AFr o/o8FpMxEX6mKbt5PuUYjxrX+tpmiJG5dCqkXyHELzVe6HIRuQnTKVFLCcqvxqWS/O9eM vt8o/PF+CC3LAOJYUOvkDCY4vM7rO69tMuxe8xesWAm3GnY/Z581pL/bjhXkcKZfYQPyH 7xag4OCVbk9GRmFsLbbQbIWj/A5TdPUe93LdbY22bkWW4eLebBeqUZejW9rTCjBYXzg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=UJNttNzB; arc=none smtp.remote-ip=95.215.58.203 Received: from mta1.migadu.com (out-203.mta1.migadu.com [95.215.58.203]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81010606A31C for ; Mon, 9 Nov 2026 05:56:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 81010606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=UJNttNzB X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=YluyIRWOfpynnfHtIz5HbTs01U9U2R3DpTwEgzyIP2Q=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794203793; v=1; x=1794808593; b=UJNttNzBMya9WCTZIdczS6jnUamZ5nEont5ISbrHHZ0FaFbQ5EQn6BNg+iyGJU/m/1eY9CN6 3A0ZVrtVpFrUPF6gofZTYMF7WKmwrZxh7N1hSYgrHrVky1EkOvZWu9RslXzTAYas8mezBUZmBNL iZuPM+eVMF0COYyFgnh54N1U= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta10.migadu.com with ESMTPS id ebe2b124efa8aa48; Mon, 09 Nov 2026 05:56:33 +0000 X-Mizu-Trace-ID: ebe2b124efa8aa48 X-Migadu-Flow: FLOW_OUT From: Baoquan He To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, david@kernel.org, chrisl@kernel.org, kasong@tencent.com, nphamcs@gmail.com, baohua@kernel.org, youngjun.park@lge.com, corbet@lwn.net, hannes@cmpxchg.org, chengming.zhou@linux.dev, kunwu.chan@gmail.com, klarasmodin@gmail.com, linux-kernel@vger.kernel.org, Baoquan He Subject: [PATCH v5 08/19] mm, swap: require zswap for xswap devices Date: Mon, 9 Nov 2026 13:54:44 +0800 Message-ID: <20261109055455.536925-9-baoquan.he@linux.dev> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261109055455.536925-1-baoquan.he@linux.dev> References: <20261109055455.536925-1-baoquan.he@linux.dev> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit From: Baoquan He xswap pages live only in zswap. Without zswap, swapout cannot free the page, but still takes a swap entry. So the device consumes swap entries without freeing memory. Fail to create a device when zswap is unavailable. Acked-by: Chris Li Signed-off-by: Baoquan He --- mm/swapfile.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/swapfile.c b/mm/swapfile.c index 3f2b863f7dd7..35c8aac1e25d 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -4268,6 +4268,10 @@ static int xswap_create(int prio) (prio < 0 || prio > SWAP_FLAG_PRIO_MASK)) return -EINVAL; + /* xswap has no backing store, it relies on zswap. */ + if (!zswap_is_enabled()) + return -EOPNOTSUPP; + si = alloc_swap_info(); if (IS_ERR(si)) return PTR_ERR(si); -- 2.54.0