From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=103.131.191.57 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792581908; b=0LZ64JYRuFEAoxUw2GqSQ9ll26vrj3cUvaTogOSRcTc96574D78rTyFnjix0eRc1auKu Y7BuyXHStF9WKmOEWSA4eAkUf7x07I+21ud3orIvBalcx9ly7f2YA8sARXzHR4HsoXNG4 p4usHJ+imyTztuPW/wjaRNGtA5VsLjfOJhWeV7fIrhw2fyXRSX9R5QGYAalf6I+8whBir li5AgHDhWz1N3TCNKEzuQlwNvNBxo0rsinZh3iqYTJB0AQ/vh9EiPWoxusLh91xCiqASf xarYYeCh8PBDnKIIouRbTvzxxeTksG9isxMNnVzXjfeb8zmmRkqn3gYEHw4jWmY94NA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792581908; h=DMARC-Filter:Received:From:To:Cc:Subject:Date:Message-Id:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding: X-HM-Tid:X-HM-MType:X-HM-Spam-Status; bh=mBXfKVl4/Kl4meR18VHWKqXqUs3LmwtSo20MC6ZTq7c=; b=vqlsa+ZXvgBIlmlQmfrxSdbpiVsBAVBfgM5DcL9FsS7AZrUyZ4D6mdTPtrwew27CMfx/ BxcIEqprI7uMJupOugI3yhbJF6zM7/BHSDGAEfzz0YPpQYG/NlG5NRGpCcOHExDwpeldq kAI5GlctCMMLlmqOMNA/SHLwScfqsivy6/bkIFLsdskguith8xIvdh9ubx7+sR8ojYEWu tCKoYIH/z2xwH6jcG3Kp9mI+NoZgxUzswqZ8VtoukAG3+7q3AwZmbwcsZgHLMyEX6F5+m KtftLYdSx+Z2k/LHLghro9MfkF1XlgeobaZ/prbt5WUrxCEI3Qpl1x4YGb05RtGkSeA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=easystack.cn; spf=pass smtp.mailfrom=easystack.cn; arc=none smtp.remote-ip=103.131.191.57 Received: from mail-m10313119157.xmail.ntesmail.com (mail-m10313119157.xmail.ntesmail.com [103.131.191.57]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A2B75606A331; Wed, 21 Oct 2026 11:25:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A2B75606A331 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=easystack.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=easystack.cn Received: from localhost.localdomain (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 204f151ad; Wed, 21 Oct 2026 19:24:55 +0800 (GMT+08:00) From: Zhen Ni To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com, ihor.solodrai@linux.dev, akpm@linux-foundation.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, ziy@nvidia.com, shuah@kernel.org Cc: bpf@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Zhen Ni Subject: [PATCH v3 5/7] mm/page_owner: record the NUMA node in the scan cursor Date: Wed, 21 Oct 2026 19:24:35 +0800 Message-Id: <20261021112437.1799213-6-zhen.ni@easystack.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20261021112437.1799213-1-zhen.ni@easystack.cn> References: <20261021112437.1799213-1-zhen.ni@easystack.cn> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-HM-Tid: 0aa15e35045c0229kunme08c1fd526ace7 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlDGkkdVk4fTklKTR5KHUlOHlYVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ Compute the page's NUMA node in page_owner_next_eligible() while the page is still valid, and store it in scan->nid. The debugfs nid filter reads scan->nid instead of recomputing it, and a BPF program iterating the cursor reads the node straight from scan->nid. Resolve nid at scan time to avoid dereferencing a possibly-unmapped page. Keep it in the transient scan cursor rather than struct page_owner, so nid does not add per-page memory overhead. Signed-off-by: Zhen Ni --- Changes in v3: - Add @scan->nid to the comment describing what is filled. Changes in v2: - Removes the v1 get_nid() kfunc. The node is now stored in scan->nid. v2: https://lore.kernel.org/linux-mm/20261013122125.843451-5-zhen.ni@easystack.cn/ v1: https://lore.kernel.org/linux-mm/20261009112308.240769-5-zhen.ni@easystack.cn/ --- mm/page_owner.c | 29 +++++++++++++++++------------ mm/page_owner.h | 1 + mm/page_owner_iter.c | 4 +++- 3 files changed, 21 insertions(+), 13 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index ece3b69a2579..8bc15bcdc24e 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -711,9 +711,22 @@ void __dump_page_owner(const struct page *page) page_ext_put(page_ext); } +/* + * NUMA node of @page, bypassing PF_POISONED_CHECK() in page_to_nid() to + * avoid VM_BUG_ON on poisoned pages; -1 for poisoned pages. + */ +static int page_owner_get_nid(struct page *page) +{ + memdesc_flags_t page_flags = READ_ONCE(page->flags); + + if (page_flags.f == PAGE_POISON_PATTERN) + return -1; + return memdesc_nid(&page_flags); +} + /* * Advance @scan to the next page eligible for page_owner output. - * On a hit, fill scan->pfn/po_snap and return true; the caller + * On a hit, fill scan->pfn/po_snap/nid and return true; the caller * must advance scan->pfn past the hit before calling again to resume * the scan. */ @@ -790,6 +803,7 @@ bool page_owner_next_eligible(struct page_owner_scan *scan) if (!scan->po_snap.handle) goto ext_put_continue; + scan->nid = page_owner_get_nid(page); page_ext_put(page_ext); put_online_mems(); return true; @@ -833,17 +847,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) goto skip_continue; if (state->nid_filter_enabled) { - int nid; - memdesc_flags_t page_flags = READ_ONCE(page->flags); - - /* - * Bypass PF_POISONED_CHECK() in page_to_nid() to avoid - * VM_BUG_ON when accessing poisoned pages. - */ - if (page_flags.f == PAGE_POISON_PATTERN) - goto skip_continue; - nid = memdesc_nid(&page_flags); - if (!node_isset(nid, state->nid_filter)) + if (scan.nid < 0 || + !node_isset(scan.nid, state->nid_filter)) goto skip_continue; } diff --git a/mm/page_owner.h b/mm/page_owner.h index 4ab513f17fc9..934bc9f84d6f 100644 --- a/mm/page_owner.h +++ b/mm/page_owner.h @@ -38,6 +38,7 @@ struct page_owner_scan { /* resume point */ unsigned long pfn; struct page_owner po_snap; + int nid; }; bool page_owner_next_eligible(struct page_owner_scan *scan); diff --git a/mm/page_owner_iter.c b/mm/page_owner_iter.c index 4b9741a2de53..b7e0ce1dfa80 100644 --- a/mm/page_owner_iter.c +++ b/mm/page_owner_iter.c @@ -12,10 +12,11 @@ struct bpf_iter__page_owner { __bpf_md_ptr(struct bpf_iter_meta *, meta); __bpf_md_ptr(struct page_owner *, po); u64 pfn; + int nid; }; DEFINE_BPF_ITER_FUNC(page_owner, struct bpf_iter_meta *meta, - struct page_owner *po, u64 pfn) + struct page_owner *po, u64 pfn, int nid) static void *page_owner_seq_start(struct seq_file *seq, loff_t *posp) { @@ -52,6 +53,7 @@ static int page_owner_prog_seq_show(struct bpf_prog *prog, /* @po: hit-time snapshot, no RCU window needed. */ ctx.po = &scan->po_snap; ctx.pfn = scan->pfn; + ctx.nid = scan->nid; } return bpf_iter_run_prog(prog, &ctx); -- 2.20.1