From patchwork Tue Dec 19 14:25:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jingbo Xu X-Patchwork-Id: 13498363 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9098C46CCD for ; Tue, 19 Dec 2023 14:25:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1F0EF8D0003; Tue, 19 Dec 2023 09:25:19 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1534C8D0001; Tue, 19 Dec 2023 09:25:19 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EC0148D0003; Tue, 19 Dec 2023 09:25:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id D71498D0001 for ; Tue, 19 Dec 2023 09:25:18 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 9976BA1DD1 for ; Tue, 19 Dec 2023 14:25:18 +0000 (UTC) X-FDA: 81583790316.10.944C187 Received: from out30-100.freemail.mail.aliyun.com (out30-100.freemail.mail.aliyun.com [115.124.30.100]) by imf09.hostedemail.com (Postfix) with ESMTP id 6968A14000E for ; Tue, 19 Dec 2023 14:25:15 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=none; spf=pass (imf09.hostedemail.com: domain of jefflexu@linux.alibaba.com designates 115.124.30.100 as permitted sender) smtp.mailfrom=jefflexu@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1702995916; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JzvlAyfuSBNRCYc7e0SW2Z5eCaS2ryGgH9YUXOqWS3Q=; b=vLm5H9LhFNqllnvzcYYJO3ndZdDc4Fmsjis3hwGlB+2VhoQSIpI5R5YR/4lpFLdw7pJpQT IEnJCevnlBvo5ZsjtFpmfy/N0KurGuYIIGis0AOi9tJ+m/tn5lDFFB9YnN/Eeg86gIRGRe NrHOSi/QuNgdI07YXnFoZ1QYnWUIjwE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1702995916; a=rsa-sha256; cv=none; b=TYyLc32CEHPDPVR0fJGNsA1DxNiMt5daLGSh0ma6w7dz8RRZu1w8w6RY9Lgj9ILixK0Wbb 7yb0jafBYyEhn9nApmNldIISjHBfSTAxzS2b6bUm2E3iY+EzWDvxznbI19k5BBeuYp2tW5 nHucleMiren9OUIz4PeLXNMhZ79zE0Y= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=none; spf=pass (imf09.hostedemail.com: domain of jefflexu@linux.alibaba.com designates 115.124.30.100 as permitted sender) smtp.mailfrom=jefflexu@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046056;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0Vyr7WbG_1702995910; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0Vyr7WbG_1702995910) by smtp.aliyun-inc.com; Tue, 19 Dec 2023 22:25:10 +0800 From: Jingbo Xu To: shr@devkernel.io, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, joseph.qi@linux.alibaba.com, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, willy@infradead.org Subject: [PATCH v3 1/2] mm: fix arithmetic for bdi min_ratio Date: Tue, 19 Dec 2023 22:25:07 +0800 Message-Id: <20231219142508.86265-2-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20231219142508.86265-1-jefflexu@linux.alibaba.com> References: <20231219142508.86265-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 6968A14000E X-Rspam-User: X-Stat-Signature: b8dfwfebb85hsrf8cdub33jw4e9n9nhr X-Rspamd-Server: rspam03 X-HE-Tag: 1702995915-522705 X-HE-Meta: U2FsdGVkX198uc1CVgH4cqPwu91bNw5fp4la6KBoxXPgl5CVoMmOuGNJ2RTY1rVyhLwrQoHAw4tw4b3+XifRczS3DTiGLavDtVcudLCpWgtkjMiO0q8Oawa05j2ZRgRvA9ZiUk6TsdHcHaOwe5/ho+POmK9vQ5X47O76j5+RawzNcXlC5SpaJCqCuqwBl7W6gAtKlXjIDL23V4WhiRcTBSglzI651rTPjJeDV1fa58uJ4DbRV7YGezJwglkyF6gBtrhJPZyF1jgRbDgrdCO3b3JPO7ptwoZWAHQkFFWCe6Bc150mvHuS/IG3pDfzVJN8RVAjQKkjX2UszTMa0Uup/6TIEXgxXj29jzlAUiXpMBVykvuJQGfw9xkXX/F7q8pLXZfK+IbjENovv76cxjS/+wi8GQTfCQXODxGAoPC9K7v/qVAjnPgGC5zv4bt8XeP/QU0bkf7sdZlU+qf5SkCkkEOrVG6ansNOXqdFXDSYw3+bewq2H7qxDiKnywLaf9/RCzC5JkDAJe12SP/Sr7VUaXTaWAZbIPyGDn86w3qdMbvAAkILl8YE3ZzHvv4Surxs5DWDv3j0bIzayOwLrZKKb/r9xAIPjqEUqW6pF7t36h0i3KbbTsw9XkXd2qo2mscM20g3xypkpWVkQrmgLv2Ct8rynj+BKlbLHGDKEfFNIxO9u1aZkghWfd+0Pm1rq1L2lYPbWCrniIkmlfbMwnH3sYSvdPVWh8oHG+ZYIr+qBJYzfv70QcQisffWPm3LWLssiuXDpT7jXrFYmQTNaKJdtgHH+EcD5BUdlJVAmCOhW4GP/XrE1xrb7ApEfQ4jCMRN9Ww3r5G7HYoyx9stGX/WwnEhap/Q/MeZD3upbzeO94T3Z1E97E6iRz2seNfNGUgZvRWEC0Xz1ghxYfht/o6xqjMr6A0A09003Y3tAOlvh5mok7mJaoTJ3Fi+3HEhbIHDNbEzfEskzd35l7yy495 6iVrc0G0 RvKlvqMTvf+TESs0vINg0kp/eKo2ZhvoI399GY68XZMXAMgWlEhbSywjuL7F9E+eZgjqdjJRFRGMKMIHhZ02PFn02VIl2iELGVyPesKG0Ot9irwwz3CcGXaFT9iaHMcJAcgXYA5d5c/g59/FpLiBMQhQGhCOMjuxEicgr X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Since now bdi->min_ratio is part per million, fix the wrong arithmetic. Otherwise it will fail with -EINVAL when setting a reasonable min_ratio, as it tries to set min_ratio to (min_ratio * BDI_RATIO_SCALE) in percentage unit, which exceeds 100% anyway. # cat /sys/class/bdi/253\:0/min_ratio 0 # cat /sys/class/bdi/253\:0/max_ratio 100 # echo 1 > /sys/class/bdi/253\:0/min_ratio -bash: echo: write error: Invalid argument Fixes: 8021fb3232f2 ("mm: split off __bdi_set_min_ratio() function") Reported-by: Joseph Qi Signed-off-by: Jingbo Xu Reviewed-by: Jan Kara --- mm/page-writeback.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index ee2fd6a6af40..2140382dd768 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -692,7 +692,6 @@ static int __bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ra if (min_ratio > 100 * BDI_RATIO_SCALE) return -EINVAL; - min_ratio *= BDI_RATIO_SCALE; spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) {