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s=arc-20220608; d=hostedemail.com; t=1778311649; a=rsa-sha256; cv=none; b=WHuH5lACqtsFwBeaHr0LgJbvSTkDiBfme+xrdvVTpt++nNWDtkgHCiCGJoz/HmLuWpgww0 vqtWD/j+2HjuWi8vFcN8X2wClDyDXQ40zizf5uBkscf0ltZmVpkrGQWi0dygLAalqr8zbv BcxTuezzek4IAWQVagYQQ9YvvmtV3y0= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=none; spf=pass (imf14.hostedemail.com: domain of zhen.ni@easystack.cn designates 45.195.24.58 as permitted sender) smtp.mailfrom=zhen.ni@easystack.cn; dmarc=pass (policy=none) header.from=easystack.cn Received: from [192.168.0.59] (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 19e7d9eab; Sat, 9 May 2026 15:27:22 +0800 (GMT+08:00) Message-ID: <9ebddab1-b7b4-462e-a920-f850cc5c55c5@easystack.cn> Date: Sat, 9 May 2026 15:27:22 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 2/3] mm/page_owner: add NUMA node filter with nodelist support To: SeongJae Park Cc: akpm@linux-foundation.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260509004417.84229-1-sj@kernel.org> From: "zhen.ni" In-Reply-To: <20260509004417.84229-1-sj@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9e0ba23dfb0229kunm3dc358b4264912 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVkZQxhLVk1IGBhIGEtLQx1KH1YVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVCQk lOS1VKS0tVSkJLQlkG X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 13E4110000D X-Stat-Signature: unqofdtfg71yf5ehcfu6k1tgmw44bu7d X-Rspam-User: X-HE-Tag: 1778311647-882997 X-HE-Meta: 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 0pIk04dO fKjNGgi8S9/jO2udLVbiWdtqFASdEOj8q0IXjYAZVVxCTzSB08xdWr/ZrD3Ir0AKeEVkSoAiD8ECjivQJh+UwZbhLtsurNzmK4JliFvNr6F7LXnV0RWBA3usbsufV8IhlbrT/TDvQeJsEb4LnV4ZMhur0Yc02zUoO75lPPjvHf1sE96c2Ok6Et3WmLjhNiADWVPzjw20LE7tJBKqawuTNeaB+NLsr/YRtkOhjhtpF/uRAtQMjO5YBElAtAO4TG2IZV36P3syYxS1m4BE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 在 2026/5/9 08:44, SeongJae Park 写道: > On Thu, 7 May 2026 14:46:42 +0800 Zhen Ni wrote: > >> Add NUMA node filtering functionality to page_owner to allow filtering >> pages by specific NUMA node(s). This is useful for NUMA-aware memory >> allocation analysis and debugging. >> >> The filter supports flexible nodelist input formats: >> - Single node: echo "0" > nid >> - Multiple nodes: echo "0,2,3" > nid >> - Node range: echo "0-3" > nid >> - Mixed format: echo "0,2-4,7" > nid >> - Clear filter: echo > nid (empty string) >> >> The implementation uses nodemask_t for efficient multi-node filtering >> and nodelist_parse() for flexible input parsing. Empty input clears >> the filter. >> >> Note: Access to nid_mask uses plain load/store without locking because >> nodemask_t is too large (128 bytes) for READ_ONCE/WRITE_ONCE. This is >> safe for debug use: low-frequency changes and torn reads would only >> cause temporary inconsistency in debug output. >> >> Signed-off-by: Zhen Ni >> --- >> >> Changes in v5: >> - Optimize nodes_empty() check in page iteration loop >> - Add __data_racy qualifier to nid_mask field > > Adding links to previous revisions [1] would be helpful. Will add lore links. > >> --- >> mm/page_owner.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 86 insertions(+) >> >> diff --git a/mm/page_owner.c b/mm/page_owner.c > [...] >> @@ -700,6 +707,9 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) >> while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) >> pfn++; >> >> + mask = owner_filter.nid_mask; >> + bool filter_by_nid = !nodes_empty(mask); >> + > > Shouldn't we separate variable declarations and statements inside a same block? > I will fix this in v6 by declaring all variables at the beginning of the block: nodemask_t mask; bool filter_by_nid; mask = owner_filter.nid_mask; filter_by_nid = !nodes_empty(mask); > [...] >> +static ssize_t nid_filter_write(struct file *file, >> + const char __user *buf, >> + size_t count, loff_t *ppos) >> +{ >> + char *kbuf; >> + nodemask_t mask; >> + int ret; >> + >> + /* >> + * Limit input size to handle worst-case nodelist (all nodes). >> + * Worst case per node: ",NNNNN" (comma + 5-digit node number) = 6 bytes. >> + * Formula: 100 bytes overhead + 6 * MAX_NUMNODES > > What is the 100 bytes overhead? The 100 bytes is intended as a safety margin, but it's not strictly necessary. Maybe I should simplify it to just 6 * MAX_NUMNODES? > >> + */ >> + if (count > (100 + 6 * MAX_NUMNODES)) >> + return -EINVAL; >> + >> + kbuf = kmalloc(count + 1, GFP_KERNEL); >> + if (!kbuf) >> + return -ENOMEM; > > Would it make sense to use kmalloc_objs()? I'll update the code to use kmalloc_objs(char, count + 1, GFP_KERNEL) Thanks for the review! > > [1] https://docs.kernel.org/process/submitting-patches.html#commentary > > > Thanks, > SJ > > [...] > > Best regards, Zhen