From nobody Wed Apr 8 01:18:42 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC030C00140 for ; Wed, 24 Aug 2022 11:31:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236863AbiHXLbh (ORCPT ); Wed, 24 Aug 2022 07:31:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235265AbiHXLbf (ORCPT ); Wed, 24 Aug 2022 07:31:35 -0400 Received: from mail.sberdevices.ru (mail.sberdevices.ru [45.89.227.171]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CFDA7CB53 for ; Wed, 24 Aug 2022 04:31:31 -0700 (PDT) Received: from s-lin-edge02.sberdevices.ru (localhost [127.0.0.1]) by mail.sberdevices.ru (Postfix) with ESMTP id 174345FD0C; Wed, 24 Aug 2022 14:31:28 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sberdevices.ru; s=mail; t=1661340688; bh=9a3LG75heqpVyPTgK4IjcsiLYbZXVWbG8+l83iknq/U=; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; b=XkmEd4qmaLG7oYQlqb7HPFZS8rXaOic64jmLQU+q7fitA/zKznETHS/WMIV82oGDl TZMSyaDc11KMeAUglxMuz+2JYPGgmdVjqpSm2yaICNbpn+yfgCykSBZwDTP3O0tmst pX9u3iQKoJDXKYSZWGscL4nr2OgxXflepL1V5MC6t805kqK0EDUaJQFagLKvTk1qyI 4CAgf6IrIkvaoVI0jfZ2iyp25AsaOzwgGwxgZNSeyBS6OMVXRGiHeWsJr1tbgTdGgm QlE919zDf1rYSKOncH4OFggTCyYvLkRfhb44crf5BqGMEsOfZM9Pk2SClFGhmD1pH2 3+/9/QnCUIHvw== Received: from S-MS-EXCH01.sberdevices.ru (S-MS-EXCH01.sberdevices.ru [172.16.1.4]) by mail.sberdevices.ru (Postfix) with ESMTP; Wed, 24 Aug 2022 14:31:26 +0300 (MSK) From: Alexey Romanov To: , , , CC: , , , Alexey Romanov , Dmitry Rokosov Subject: [PATCH v2] zram: don't retry compress incompressible page Date: Wed, 24 Aug 2022 14:31:17 +0300 Message-ID: <20220824113117.78849-1-avromanov@sberdevices.ru> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [172.16.1.6] X-ClientProxiedBy: S-MS-EXCH01.sberdevices.ru (172.16.1.4) To S-MS-EXCH01.sberdevices.ru (172.16.1.4) X-KSMG-Rule-ID: 4 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Status: not scanned, disabled by settings X-KSMG-AntiSpam-Interceptor-Info: not scanned X-KSMG-AntiPhishing: not scanned, disabled by settings X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 1.1.2.30, bases: 2022/08/24 08:05:00 #20147978 X-KSMG-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" It doesn't make sense for us to retry to compress an uncompressible page (comp_len =3D=3D PAGE_SIZE) in zsmalloc slowpath, because we will be storing it uncompressed anyway. We can avoid wasting time on another compression attempt. It is enough to take lock (zcomp_stream_get) and execute the code below. Signed-off-by: Alexey Romanov Signed-off-by: Dmitry Rokosov Reviewed-by: Sergey Senozhatsky --- drivers/block/zram/zram_drv.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 226ea76cc819..3bd8d5e27041 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1410,9 +1410,19 @@ static int __zram_bvec_write(struct zram *zram, stru= ct bio_vec *bvec, handle =3D zs_malloc(zram->mem_pool, comp_len, GFP_NOIO | __GFP_HIGHMEM | __GFP_MOVABLE); - if (!IS_ERR((void *)handle)) + if (IS_ERR((void *)handle)) + return PTR_ERR((void *)handle); + + if (comp_len !=3D PAGE_SIZE) goto compress_again; - return PTR_ERR((void *)handle); + /* + * If the page is not compressible, you need to acquire the lock and + * execute the code below. The zcomp_stream_get() call is needed to + * disable the cpu hotplug and grab the zstrm buffer back. + * It is necessary that the dereferencing of the zstrm variable below + * occurs correctly. + */ + zstrm =3D zcomp_stream_get(zram->comp); } =20 alloced_pages =3D zs_get_total_pages(zram->mem_pool); --=20 2.25.1