From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=103.129.254.92 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792581904; b=V7eoQiWGz2pZpzmg/ZjLrWXtmNMlhUlThb6hzbtYgzEypp1N660A3HEZJ7yhlNJCSY5r pphiZzIPq9ybDDiqUggP4J9vRiHxUsFvNUESo2OczXOeNTRwcyKwHXcOmzylat32ORCPi izA3z0M5c2yFdAITyAXuQR0fJuA+4vaeWffu+cT4phuvKy0K+AgbPIUoVK0lcqz+OfExk QomhjRSijuOFlhrs7FvpIT+Nbk7mBg7JGiSFB/4BSX8QhvhmBNRi33l/Tjjo2TLeEo9kZ 93T8EwD79AX7065IG5g010zqP5q5lii4y39wwjhdniQN5DdwDHO1L9jLnO5jPXcga7g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792581904; 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=EPDlZMTSTVQ5eCE68sbvYSTGTpxshvufAloZkiCKtC0=; b=3ZNJTS7U++rMcG4aiS918xAqt3GUsuPGfaZVX7QVx2JwvFJc8I67ng9hkcX5cQPJvbpq wdZ435yj2d+Dy2NZYk/V7ZaLZjAcyTlA0IosE0k2mQ9L9euohp8S7cSXbVBmIZTtd+HHA 0PtgWUsjqxpMMQUMXvoZI+mgfQOol25KnJXgWmLJ+R7AgLwuqZsH8DKICqA9R6S/qg+gj /psa2+s1xVqPwMAXsrMpHag8j98fWuKDmfmDxVLstNFCMAGZeVqhpzF1bUyfx3kUkQvYy PRqQUpQydgiTDqqRPYUUv4b8k14S4ZI1/Op+Hv9bOEhv+hkc0TDRU12A+h20ZswpNmA== 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=103.129.254.92 Received: from mail-m25492.xmail.ntesmail.com (mail-m25492.xmail.ntesmail.com [103.129.254.92]) (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 3C5F8606A330; Wed, 21 Oct 2026 11:25:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3C5F8606A330 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 204f151ab; Wed, 21 Oct 2026 19:24:53 +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 4/7] mm/page_owner: add open-coded page_owner iterator Date: Wed, 21 Oct 2026 19:24:34 +0800 Message-Id: <20261021112437.1799213-5-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: 0aa15e34fe6f0229kunme08c1fd526ace2 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlCSkNMVk9KT0JPSk5NGB5CT1YVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ Add an open-coded bpf_iter over the pages eligible for page_owner output, reusing page_owner_next_eligible(). A sleepable BPF program drives it with bpf_iter_page_owner_new()/next()/destroy(); each next() returns the page_owner_scan. po_snap is copied inside the page_ext RCU window, so the program needs no RCU section when it reads it. Also add bpf_page_owner_stack_snprint(), which renders the stack trace of the current page into a caller-provided buffer. Signed-off-by: Zhen Ni --- Changes in v3: - Gate the kfuncs with KF_PERFMON. - Check the page_owner_inited static key in the iterator. - Without scan->page, start at min_low_pfn - 1 and let next() pre-increment. - bpf_page_owner_stack_snprint() rejects a NULL or zero-size buffer. Changes in v2: - bpf_page_owner_stack_snprint() now takes the scan cursor. - Buffer args renamed to buf__uninit/buf__sz. v2: https://lore.kernel.org/linux-mm/20261013122125.843451-4-zhen.ni@easystack.cn/ v1: https://lore.kernel.org/linux-mm/20261009112308.240769-4-zhen.ni@easystack.cn/ --- kernel/bpf/helpers.c | 9 +++++++ mm/page_owner.h | 3 +++ mm/page_owner_iter.c | 64 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 76 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 712dca5a2c5b..0ba836f77957 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -4946,6 +4946,15 @@ BTF_ID_FLAGS(func, bpf_iter_dmabuf_new, KF_ITER_NEW | KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_iter_dmabuf_next, KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_iter_dmabuf_destroy, KF_ITER_DESTROY | KF_SLEEPABLE) #endif +#ifdef CONFIG_PAGE_OWNER +BTF_ID_FLAGS(func, bpf_iter_page_owner_new, + KF_ITER_NEW | KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_iter_page_owner_next, + KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_iter_page_owner_destroy, + KF_ITER_DESTROY | KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_page_owner_stack_snprint, KF_SLEEPABLE | KF_PERFMON) +#endif BTF_ID_FLAGS(func, __bpf_trap) BTF_ID_FLAGS(func, bpf_strcmp, KF_PERFMON); BTF_ID_FLAGS(func, bpf_strcasecmp, KF_PERFMON); diff --git a/mm/page_owner.h b/mm/page_owner.h index 0aa7695bec82..4ab513f17fc9 100644 --- a/mm/page_owner.h +++ b/mm/page_owner.h @@ -6,6 +6,7 @@ #ifndef __MM_PAGE_OWNER_H #define __MM_PAGE_OWNER_H +#include #include #include #include @@ -13,6 +14,8 @@ /* * mm/page_owner.c */ +DECLARE_STATIC_KEY_FALSE(page_owner_inited); + struct page_owner { unsigned short order; short last_migrate_reason; diff --git a/mm/page_owner_iter.c b/mm/page_owner_iter.c index 529b2c4a589a..4b9741a2de53 100644 --- a/mm/page_owner_iter.c +++ b/mm/page_owner_iter.c @@ -4,6 +4,7 @@ #include #include #include +#include #include "page_owner.h" @@ -116,3 +117,66 @@ int page_owner_iter_register(void) return bpf_iter_reg_target(&page_owner_iter_reg_info); } + +/* opaque to BPF programs */ +struct bpf_iter_page_owner { + __u64 __opaque[16]; +} __attribute__((aligned(8))); + +struct bpf_iter_page_owner_kern { + struct page_owner_scan scan; +} __attribute__((aligned(8))); + +__bpf_kfunc_start_defs(); + +__bpf_kfunc int bpf_iter_page_owner_new(struct bpf_iter_page_owner *it) +{ + struct bpf_iter_page_owner_kern *kit = (void *)it; + + BUILD_BUG_ON(sizeof(*kit) > sizeof(*it)); + BUILD_BUG_ON(__alignof__(*kit) != __alignof__(*it)); + + kit->scan.pfn = min_low_pfn - 1; + return 0; +} + +__bpf_kfunc struct page_owner_scan * +bpf_iter_page_owner_next(struct bpf_iter_page_owner *it) +{ + struct bpf_iter_page_owner_kern *kit = (void *)it; + + if (!static_branch_unlikely(&page_owner_inited)) + return NULL; + + cond_resched(); + + kit->scan.pfn++; + if (!page_owner_next_eligible(&kit->scan)) + return NULL; + + return &kit->scan; +} + +__bpf_kfunc void bpf_iter_page_owner_destroy(struct bpf_iter_page_owner *it) +{ +} + +__bpf_kfunc int bpf_page_owner_stack_snprint(struct page_owner_scan *scan, + char *buf__uninit, u32 buf__sz) +{ + int len = 0; + + if (!buf__uninit || !buf__sz) + return 0; + + if (static_branch_unlikely(&page_owner_inited)) + len = stack_depot_snprint(scan->po_snap.handle, buf__uninit, + buf__sz, 0); + + if (!len) + buf__uninit[0] = '\0'; + + return len; +} + +__bpf_kfunc_end_defs(); -- 2.20.1