From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6306641834B for ; Fri, 7 Aug 2026 10:05:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786097159; cv=none; b=gUuf5Pim0Vcw6p+ecRMNsv5Nta7+0EyVqcj6m5+gUtp16tcmkQU2YrbaAJaGYbBWq/2L5IbwVXo//fSPVwrG/uoNjda8eKX6b0W5dCNShwXAOlpml7zCugLQ9htqsavXFUHkJMGnW5oOq+IZrnQMEKBSwmi0vAMnNXZjF0YiTv0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786097159; c=relaxed/simple; bh=9UxKM7Hscn8U/hGj6SGYL7LtcEKmRunUFlcB0cPAEjg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ibamBKURoF9vs0m7rpCN1HHDWQMkpY5NohLxG+9+cPoBwRYYSMyKeerXbkzlk+8YTluObT0LjGkgbshC9qKrjcsrHMiaowBilo+2bYgZPYTAsUCUN9BruSgvedfDtPQCwYYWfMri8vvGS188jtBIU/hKv6/6E1yP0dSz5h42XhA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=I7RODPVc; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="I7RODPVc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01DD61F000E9; Fri, 7 Aug 2026 10:05:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786097157; bh=O3Y82uuF/XQW5iDFHNIUgMEdIc1HrOdEgL8h46LMPJ8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=I7RODPVcJBRsd6s9UWRbtl8lpLOuBZpmxFX36HCqgpaIVZNVcAujidNCKp4lU2FFe BAm1Sq94dhTqpSAovKm8Qh0kXVTk4OAQ/EgO69kB7YrXIJOSCR3U1XsIEdq5+PQj10 dgsj562UwM3s3jCZHLRr76XK0JLD0TgCBH/4qVwMueLXjV59DBZ080kXS6S8sd9xO9 dakp9bUiDf+bNOEaUGRXfrC+ZEcoMu7JNmMhqMRnS+jsDDRTLzjdmrIIJlVcLWVmQ9 u5ExWj5KFg4XfPKlyW3XiWRNCETRpSCzh7i3n/3YhxppLjDvmfAIQ6+yPKfkV6Mpni yea7I4chqnnyA== Message-ID: <2fcfa480-e4dd-477f-9c02-42756f3aa373@kernel.org> Date: Fri, 7 Aug 2026 12:05:53 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5] mm/page_alloc: only update lowmem_reserve_ratio on sysctl write To: Jianlin Shi , linux-mm@kvack.org Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, ziy@nvidia.com, linux-kernel@vger.kernel.org References: From: "Vlastimil Babka (SUSE)" Content-Language: en-US Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/6/26 10:27, Jianlin Shi wrote: > lowmem_reserve_ratio_sysctl_handler() ignores the return value of > proc_dointvec_minmax() and always calls setup_per_zone_lowmem_reserve(), > even for read operations. > > Fix three issues: > > 1. Propagate errors from proc_dointvec_minmax() instead of always > returning success. For example, writing non-integer garbage to the > sysctl now returns an error instead of silently succeeding with > unchanged values. > > 2. Only call setup_per_zone_lowmem_reserve() when the sysctl is > actually written, matching the write-only refresh pattern of > min_free_kbytes and watermark_scale_factor handlers. > > 3. On write, parse into a temporary ratio[] array and only copy into > sysctl_lowmem_reserve_ratio[] and refresh derived state after the > full vector is validated. This avoids leaving the ratio array > partially updated while skipping setup when proc_dointvec_minmax() > returns an error on a later element (suggested by Andrew Morton). > > Drop the manual "< 1 -> 0" sanitization loop and set .extra1 = > SYSCTL_ZERO on the ctl_table entry so proc_dointvec_minmax() enforces > the minimum on write; negative values now return -EINVAL instead of > being silently coerced to 0 (suggested by Vlastimil Babka). > > Link: https://lore.kernel.org/linux-mm/tencent_FFD4F4D728AAE8A8AE0AF277A59854A29A06@qq.com/ > > Signed-off-by: Jianlin Shi Acked-by: Vlastimil Babka (SUSE)