From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 DF818382F15 for ; Mon, 20 Apr 2026 19:03:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776711789; cv=none; b=VtD6Pa/RzCVa//xMCrDqHpH+sCJumbfB0tcsLnFL57dkRqYDWFMJ3YXBTBswb4B6pFfHstRj8f5lusYu1VqKUY8PqqT8kAUqSfFnyuIDUyMrIRAkPsQJZOVlQXf/h2y0rb+a79va3dofwvKWUaDOQSyXUfB3I/HjmiA1Xrg2iRo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776711789; c=relaxed/simple; bh=HCf8DsqrqtUoC3kEuRnRvbL+Njp65zOlbz2OuhLRP1E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=hxX3TGPppHYys7YBouBxaswCEK6Z8JwqT34oqQwwwGzHwiutu21g34kUMW+Y1uX2uf/ObzusfrBMx+LXt5zUWIvR1vG56u9SUXopnhwKaMYIYiQP4pYGNffp4H0JUR9riN/2ZJFPv7yQv0uG6uxhmut5EpmBrwCg4o0Fk9rpiG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UTxb0bxf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UTxb0bxf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FE27C19425; Mon, 20 Apr 2026 19:03:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776711789; bh=HCf8DsqrqtUoC3kEuRnRvbL+Njp65zOlbz2OuhLRP1E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=UTxb0bxf0p9SPGEz9c3QpVnszUtxBZp8b1Ewfcg5N9lAntzEIcDLXzN7AJts++4yy T4Zqs912LANKgvHFYt2K2Cp4dmiB4jWbjLdg2CP3iSJMLvosJc2dpCsUTqIbCW3Ap8 SykFg4rNgwuL9fA3KwKuxGeiGJNOc6wcS2DR3dpCp7+2mphDlupSbw2QXo4NOZ7qCM 3V4MIhpkKrYSNDNKlHKq0DZHZB4HVyf0HInlsg8aTte2nZyh+ePBBs1sHMbcihbUBO YTLzFYBgoE63K/l55t22vG6PY6Xvso7AMEPv1bY9x3voVlYzYkt8EWuwmxHUkYkbox tqGCfkEPFY+eQ== Message-ID: <5bebc75d-19e7-4d06-a5c1-d3f0bb5f4e05@kernel.org> Date: Mon, 20 Apr 2026 21:03:04 +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 -next] mm: make sure freeram is smaller than totalram To: Yang Yingliang , akpm@linux-foundation.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, hucool.lihua@huawei.com References: <20260413115736.1237680-1-yangyingliang@huawei.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/13/26 13:57, Yang Yingliang wrote: > The memory stat is not done in real time, it have some gap with > real value. In CPU-less NUMA node, the values of MemTotal and > MemFree can be nearly equal, the gap may cause MemFree bigger > than MemTotal, it leads MemUsed is negative which print as a large > positive number. How does this interact with CPU-less NUMA node? Some concurrent memory hotunplug, or how could be possible get MemFree that is larger than MemTotal? > > cat /sys/devices/system/node/node17/meminfo > Node 17 MemTotal: 4194304 kB > Node 17 MemFree: 4195552 kB > Node 17 MemUsed: 18446744073709550368 kB > Node 17 Active: 52 kB > Node 17 Inactive: 320 kB > Node 17 Active(anon): 0 kB > Node 17 Inactive(anon): 0 kB > Node 17 Active(file): 52 kB > Node 17 Inactive(file): 320 kB > Node 17 Unevictable: 0 kB > Node 17 Mlocked: 0 kB > Node 17 Dirty: 0 kB > Node 17 Writeback: 0 kB > Node 17 FilePages: 372 kB > Node 17 Mapped: 320 kB > Node 17 AnonPages: 0 kB > Node 17 Shmem: 0 kB > Node 17 KernelStack: 0 kB > Node 17 PageTables: 0 kB > Node 17 NFS_Unstable: 0 kB > Node 17 Bounce: 0 kB > Node 17 WritebackTmp: 0 kB > Node 17 KReclaimable: 0 kB > Node 17 Slab: 0 kB > Node 17 SReclaimable: 0 kB > Node 17 SUnreclaim: 0 kB > Node 17 AnonHugePages: 79872 kB > Node 17 ShmemHugePages: 0 kB > Node 17 ShmemPmdMapped: 0 kB > Node 17 FileHugePages: 0 kB > Node 17 FilePmdMapped: 0 kB > Node 17 HugePages_Total: 0 > Node 17 HugePages_Free: 0 > Node 17 HugePages_Surp: 0 > > To avoid this exception by refreshing vm_stat, when MemFree > is bigger than MemTotal. > -- Cheers, David