From nobody Tue Sep 29 09:09:31 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.2]) (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 1AF8C39658D; Mon, 10 Aug 2026 09:47:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.2 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786355254; cv=none; b=VxkoXHQIaEV2CyOqciUvkoRcmC7UimKXP+TTVWRxRDgKYbMWjs88DSHwyR1jsBNKyu2L2wi/hLfLtBNTFgAus5AJwOYCgKrGxWKxJx5YVybvtuZEjgkdWnSh+T7HMBsEY9MQy0fT8mUk6bcGSEUXzEeQvuYyZB/DrFjx8XqMYVM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786355254; c=relaxed/simple; bh=NiyyWUH1prkVse1OkE9B2qMJ6JZL7ZE6Xekm99UEJDo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f1Sg4t6sC8siDVzyq0keWmqT1iiPZXEBRmxul+BQYXUFlQuI8b9/sT2ur9133t1S7taUvRMYsa/NSVbseNJZBM+6mnr5AdGc0iKwpcDjeF25oBZlYiO6Y9XmTsaUo/kBkGSRmkpMjfWBsxf3f/1TaGDgX5+zNiXOgJtUSK7dSVU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=YWRHkeFt; arc=none smtp.client-ip=220.197.31.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="YWRHkeFt" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=+J HuhUJjxcmnFhFTzIqRT3sPERPM9fOZMeWKzbtsUd0=; b=YWRHkeFt+42H8fzQtQ KYH5up6PEsCQRCavzvBh+d5lmTedfpz02CPgBqXBygQ27TVKuhC2vj5akSiQEE0q 6nPIEs1ErW+M3UfIWQbhZ2Ont0B4cGGGVjGhhDkGk7XDzdgdQnZZWitit0fKU6zi IobQka3iLSY+eA/WyOkRfMTqo= Received: from nec8-i7 (unknown []) by gzga-smtp-mtada-g0-3 (Coremail) with SMTP id _____wB3EocEnnlqAlAcOg--.9113S3; Mon, 10 Aug 2026 17:46:48 +0800 (CST) From: chenyuan_fl@163.com To: bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Yuan Chen Subject: [PATCH bpf-next v2 1/3] bpf, arena: fix range_tree_clear inconsistency on kmalloc_nolock failure Date: Mon, 10 Aug 2026 17:46:32 +0800 Message-ID: <20260810094634.2723213-2-chenyuan_fl@163.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260810094634.2723213-1-chenyuan_fl@163.com> References: <20260810094634.2723213-1-chenyuan_fl@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wB3EocEnnlqAlAcOg--.9113S3 X-Coremail-Antispam: 1Uf129KBjvJXoW7Cw48Xw45trWrXFyUuFW8tFb_yoW8GF1fpw 4UK34fAws0q3yUWrZa9F4vkr98Can3Xr48K343tw4kAr15A3Z7urnY9r4293ZrAFZFy3Wr tF1jva9rK3WUuFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UZeOXUUUUU= X-CM-SenderInfo: xfkh05pxdqswro6rljoofrz/xtbC5giiYGp5ngj98gAA3m Content-Type: text/plain; charset="utf-8" From: Yuan Chen range_tree_clear() pre-allocates the right-half node before modifying the tree, so an allocation failure returns -ENOMEM without altering the range tree. Signed-off-by: Yuan Chen --- kernel/bpf/range_tree.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/range_tree.c b/kernel/bpf/range_tree.c index 2f28886f3ff7..15b588377a76 100644 --- a/kernel/bpf/range_tree.c +++ b/kernel/bpf/range_tree.c @@ -143,16 +143,22 @@ int range_tree_clear(struct range_tree *rt, u32 start= , u32 len) if (rn->rn_start < start && rn->rn_last > last) { u32 old_last =3D rn->rn_last; =20 + /* + * Pre-allocate the right-half node before modifying + * the tree. If allocation fails we return -ENOMEM + * without altering the range tree. + */ + new_rn =3D kmalloc_nolock(sizeof(struct range_node), + __GFP_ACCOUNT, NUMA_NO_NODE); + if (!new_rn) + return -ENOMEM; + /* Overlaps with the entire clearing range */ range_it_remove(rn, rt); rn->rn_last =3D start - 1; range_it_insert(rn, rt); =20 - /* Add a range */ - new_rn =3D kmalloc_nolock(sizeof(struct range_node), __GFP_ACCOUNT, - NUMA_NO_NODE); - if (!new_rn) - return -ENOMEM; + /* Add right-half range */ new_rn->rn_start =3D last + 1; new_rn->rn_last =3D old_last; range_it_insert(new_rn, rt); --=20 2.54.0 From nobody Tue Sep 29 09:09:31 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.2]) (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 EF90F3B14B4; Mon, 10 Aug 2026 09:47:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.2 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786355254; cv=none; b=oet52YUjKFTCA/yKRtN0tnNWYlhdqglS+/ErnJH6PJn40lBz519CPIUo+z434nV/SaQSMzotjsJMNUt27JbaNLI7no4RtmY8CMVvK1GgZQ8A0t9Xw368VJUBckTtnchyupXOIZq5LxJGWi3YC5cVm1j5oUjtf4B8gHofwehxjic= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786355254; c=relaxed/simple; bh=s0eDlEyhWhKwZINONwJAuf9I/2mSlEEBqqnzWw018TU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D1fgJ7FXUH/w1Uh1KnKzaaLV4kHCndflrA3zuFPgab5fwyOd1FfpKsNy2P2sVwzG5rs5db7heeYNlzyvCxtop322sHYz/Mf8ePDsVWwmSuZGkqxHpfimhocDvS44yI86u/WpisxId5/HB2goQxGirYKqlWpJYatrTK6QT3ypxBQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=aSethP9p; arc=none smtp.client-ip=220.197.31.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="aSethP9p" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=tL TL2ZpglUla0GwJf+IdatjY2pI7kZBakztj9ClJ+Y0=; b=aSethP9pAMthcxjiwK gWaugtb5JVX2gdbbaq5CshpTKvuVHuPSTv6V9/oZ3+ZjVoivoW1XKeU+FpjDzLxf xaWBHv8v6fSaOVCUTQhnWeGV4LRuRYS1fpajInyxr6b5GjOlWjA0IBiwaklxCxA4 gujzxPGWCvnxOLeczx2zoQKNk= Received: from nec8-i7 (unknown []) by gzga-smtp-mtada-g0-3 (Coremail) with SMTP id _____wB3EocEnnlqAlAcOg--.9113S4; Mon, 10 Aug 2026 17:46:49 +0800 (CST) From: chenyuan_fl@163.com To: bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Yuan Chen Subject: [PATCH bpf-next v2 2/3] bpf, arena: fix range_tree_set inconsistency on kmalloc_nolock failure Date: Mon, 10 Aug 2026 17:46:33 +0800 Message-ID: <20260810094634.2723213-3-chenyuan_fl@163.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260810094634.2723213-1-chenyuan_fl@163.com> References: <20260810094634.2723213-1-chenyuan_fl@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wB3EocEnnlqAlAcOg--.9113S4 X-Coremail-Antispam: 1Uf129KBjvJXoWxCw13AF1kWr48GF4xAFy8Grg_yoW5CF4Upw 45KrWrJrsxJ3yxWr1Svr4ruryrCw1fXws5trZrGw4kA3ZxAr97Arn0kF4jkFWDAFykCr15 tF1jva1UKF4UuFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jbIDcUUUUU= X-CM-SenderInfo: xfkh05pxdqswro6rljoofrz/xtbDAQmiYGp5ngmVIAAA37 Content-Type: text/plain; charset="utf-8" From: Yuan Chen range_tree_set() pre-allocates the node needed for a brand-new range before calling range_tree_clear(), so an allocation failure returns -ENOMEM without having modified the tree (previously the overlapping nodes were already removed by range_tree_clear() before the allocation was attempted, permanently losing the cleared sub-ranges). Signed-off-by: Yuan Chen --- kernel/bpf/range_tree.c | 45 +++++++++++++++++++++++++++++++---------- 1 file changed, 34 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/range_tree.c b/kernel/bpf/range_tree.c index 15b588377a76..54055b1fe541 100644 --- a/kernel/bpf/range_tree.c +++ b/kernel/bpf/range_tree.c @@ -199,6 +199,7 @@ int is_range_tree_set(struct range_tree *rt, u32 start,= u32 len) int range_tree_set(struct range_tree *rt, u32 start, u32 len) { u32 last =3D start + len - 1; + struct range_node *new_rn =3D NULL; struct range_node *right; struct range_node *left; int err; @@ -208,20 +209,40 @@ int range_tree_set(struct range_tree *rt, u32 start, = u32 len) if (left && left->rn_start <=3D start && left->rn_last >=3D last) return 0; =20 + /* + * A new node is needed only when the range has no adjacent free + * range on either side. This is known before clearing: any range + * covering start - 1 or last + 1 survives the clear as an adjacent + * piece. Allocate only in that case, before modifying the tree, so + * a failure leaves the range tree unmodified + */ + left =3D range_it_iter_first(rt, start - 1, start - 1); + right =3D range_it_iter_first(rt, last + 1, last + 1); + if (!left && !right) { + new_rn =3D kmalloc_nolock(sizeof(struct range_node), + __GFP_ACCOUNT, NUMA_NO_NODE); + if (!new_rn) + return -ENOMEM; + } + /* Clear out everything in the range we want to set. */ err =3D range_tree_clear(rt, start, len); if (err) - return err; + goto out_free_new; =20 /* Do we have a left-adjacent range ? */ left =3D range_it_iter_first(rt, start - 1, start - 1); - if (left && left->rn_last + 1 !=3D start) - return -EFAULT; + if (left && left->rn_last + 1 !=3D start) { + err =3D -EFAULT; + goto out_free_new; + } =20 /* Do we have a right-adjacent range ? */ right =3D range_it_iter_first(rt, last + 1, last + 1); - if (right && right->rn_start !=3D last + 1) - return -EFAULT; + if (right && right->rn_start !=3D last + 1) { + err =3D -EFAULT; + goto out_free_new; + } =20 if (left && right) { /* Combine left and right adjacent ranges */ @@ -241,14 +262,16 @@ int range_tree_set(struct range_tree *rt, u32 start, = u32 len) right->rn_start =3D start; range_it_insert(right, rt); } else { - left =3D kmalloc_nolock(sizeof(struct range_node), __GFP_ACCOUNT, NUMA_N= O_NODE); - if (!left) - return -ENOMEM; - left->rn_start =3D start; - left->rn_last =3D last; - range_it_insert(left, rt); + /* No adjacent ranges; use the pre-allocated node */ + new_rn->rn_start =3D start; + new_rn->rn_last =3D last; + range_it_insert(new_rn, rt); } return 0; + +out_free_new: + kfree_nolock(new_rn); + return err; } =20 void range_tree_destroy(struct range_tree *rt) --=20 2.54.0 From nobody Tue Sep 29 09:09:31 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.3]) (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 B1C413B14D8; Mon, 10 Aug 2026 09:47:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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charset="utf-8" From: Yuan Chen arena_free_pages() and arena_free_worker() now handle range_tree_set() errors. arena_free_pages() aborts the free on error, and arena_free_worker() moves range_tree_set() before PTE clearing so that a failed tree update leaves the PTEs intact instead of freeing pages that the arena free tree does not track. Signed-off-by: Yuan Chen --- kernel/bpf/arena.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c index 555ee2531ef9..b374ebf2a4de 100644 --- a/kernel/bpf/arena.c +++ b/kernel/bpf/arena.c @@ -881,7 +881,12 @@ static void arena_free_pages(struct bpf_arena *arena, = long uaddr, long page_cnt, if (ret) goto defer; =20 - range_tree_set(&arena->rt, pgoff, page_cnt); + ret =3D range_tree_set(&arena->rt, pgoff, page_cnt); + if (ret) { + raw_res_spin_unlock_irqrestore(&arena->spinlock, flags); + bpf_map_memcg_exit(old_memcg, new_memcg); + return; + } =20 init_llist_head(&free_pages); cdata.arena =3D arena; @@ -1004,11 +1009,18 @@ static void arena_free_worker(struct work_struct *w= ork) kaddr =3D arena_vm_start + s->uaddr; pgoff =3D compute_pgoff(arena, s->uaddr); =20 + /* + * Mark the range as free before clearing PTEs so that + * if the range tree update fails we leave the PTEs + * intact, avoiding an unrecoverable state where pages + * are freed but the arena free tree does not track them. + */ + if (range_tree_set(&arena->rt, pgoff, page_cnt)) + continue; + /* clear ptes and collect pages in free_pages llist */ apply_to_existing_page_range(&init_mm, kaddr, page_cnt << PAGE_SHIFT, apply_range_clear_cb, &cdata); - - range_tree_set(&arena->rt, pgoff, page_cnt); } raw_res_spin_unlock_irqrestore(&arena->spinlock, flags); =20 --=20 2.54.0