From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) (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 0E9F122E3F0 for ; Thu, 11 Dec 2025 02:35:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765420515; cv=none; b=jrfs8hu5DMqMcjYFa+muZhRqSlrq7+v5l4fIEclMRQv92BzN1ahbSYN35gnnkPNy2ZC6PARuCtv9h9XfHfwCDXhTpCZlfZFwLCndFsXkAuDWxRM4Ieo6EA/902aQm25gRCpXhaC7FNKY+DnWi/ZczuxejaqiZJEfe1XladnJf8Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765420515; c=relaxed/simple; bh=LyCpG3hePJmnW1ayV0jI53RnNs4s8cKZMYdVeVQ6Fa8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ObdHApc3TsV22j5Xe+RIzC30b2l2wUlVvA9ZQhAFgqnShM2PeFslJrGJ+9d4RS0BzGMkbEfHu2MeLbALH7FOpk1UBG04Udt384aUtUP/hXbUiRXd0Un0BGrLBrw7B6OLkFbUZccyLHPkhabLy151TrmYe6OUlBB8iCEWs6N0HD0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=deaW0JTq; arc=none smtp.client-ip=115.124.30.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="deaW0JTq" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1765420510; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=n2jJgkK2KobzA0ab3tmCBUkHTgyBbt61Pm4yK6ymxRQ=; b=deaW0JTqVE54YaWWSiYnvO4sZLt2OVM07xKsaojyZ53d1mRckLFTHNBa9gludRFofYEhTuZNx0UDo0xYYhnCS7OZUaeiFx5bZHN1KK9hqrTs5G+Nq4N5tK3xelxkTN15v7kjuxvJ289wo5aCVSe9VOQSQO1jmVueaiBSTwTmAEM= Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0WuYgR-c_1765420509 cluster:ay36) by smtp.aliyun-inc.com; Thu, 11 Dec 2025 10:35:09 +0800 From: Jingbo Xu To: gregkh@linuxfoundation.org, sashal@kernel.org, stable@vger.kernel.org Cc: jefflexu@linux.alibaba.com Subject: [PATCH 2/2] mm: fix arithmetic for max_prop_frac when setting max_ratio Date: Thu, 11 Dec 2025 10:35:07 +0800 Message-Id: <20251211023507.82177-3-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20251211023507.82177-1-jefflexu@linux.alibaba.com> References: <20251211023507.82177-1-jefflexu@linux.alibaba.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit commit fa151a39a6879144b587f35c0dfcc15e1be9450f upstream. Since now bdi->max_ratio is part per million, fix the wrong arithmetic for max_prop_frac when setting max_ratio. Otherwise the miscalculated max_prop_frac will affect the incrementing of writeout completion count when max_ratio is not 100%. Link: https://lkml.kernel.org/r/20231219142508.86265-3-jefflexu@linux.alibaba.com Fixes: efc3e6ad53ea ("mm: split off __bdi_set_max_ratio() function") Signed-off-by: Jingbo Xu Cc: Joseph Qi Cc: Matthew Wilcox (Oracle) Cc: Stefan Roesch Signed-off-by: Andrew Morton --- mm/page-writeback.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 3929bb0a7501..e7a7233f6d5d 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -750,7 +750,8 @@ static int __bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ra ret = -EINVAL; } else { bdi->max_ratio = max_ratio; - bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100; + bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / + (100 * BDI_RATIO_SCALE); } spin_unlock_bh(&bdi_lock); -- 2.19.1.6.gb485710b