From nobody Fri Oct 2 01:56:20 2026 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.2]) (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 255D030D3EF; Thu, 6 Aug 2026 03:05:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.2 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785985506; cv=none; b=bKKYp0kUC+pcfQIVsf2hORq+E4UXjrgwzIIMyAdO1bgfbCI6V5gBVCMFxRR1pFs72AQAW1D84VV2X8SYKyhHJNbDOzFHAAZEgnndEf3jPq+OJW656ydoPnzqkufJhiXqiUEh9bJ30MShgXlARBTUroTOTh6Zr/abfbIUz9vJJC4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785985506; c=relaxed/simple; bh=HubZqEzSK2piMJ7hYh/WQ9CRCGWd/f972rfvQ5fHS4Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OtxvAicInDMPBGnrPR+XQTW9KwxQ3tB4wVG0PPOzRrx0ap0jKNOt205s6eOHE3sBtvh06/Q5KKeFn7PQ+7v4PA8pLNRQ/Sl5kwXiN2tzubAG0O5yaGxx2Tj0TuROiLvdYDhqrL61pFwbsKdYKVYjpkiWMXw3tbT6Un6Vm4FJRy8= 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=dKLPXBQ+; arc=none smtp.client-ip=117.135.210.2 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="dKLPXBQ+" 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=1t GJzcPujlQGstMnC2Nxu2HVEszqw9Kw3q1K1Tu/+Mw=; b=dKLPXBQ+CL6L1XhCKG vmxs4y6WKxOp95Cz+pRP7MfuAD07n1qnDcB4ajZleP+uDdKcj+M0tooBQH7S6Xf9 fYMzZCX17HWE/z4wnzemjMwciI1bYNWcrAlWlRzeCNSVcmf/mhKPEx04jsgcL8jm gdXbQE8l8Iiw37M9Ay1/W68io= Received: from nec8-i7 (unknown []) by gzsmtp5 (Coremail) with SMTP id QCgvCgD3Xy2m+XNqWvt+Kw--.33251S3; Thu, 06 Aug 2026 11:04:10 +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 v1 1/3] bpf, arena: fix range_tree_clear inconsistency on kmalloc_nolock failure Date: Thu, 6 Aug 2026 11:03:57 +0800 Message-ID: <20260806030359.299480-2-chenyuan_fl@163.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260806030359.299480-1-chenyuan_fl@163.com> References: <20260806030359.299480-1-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: QCgvCgD3Xy2m+XNqWvt+Kw--.33251S3 X-Coremail-Antispam: 1Uf129KBjvJXoW7AFWUur13Gr4DJrWkGw48JFb_yoW8WFW5pw 4UK345C390q3yUWa9aga1kCry5Ca1fXr48taySgw4vyw15Aws7ZrnY9r429ayDCFZ2v3W5 tF1jva1xK3WUuFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UCPfdUUUUU= X-CM-SenderInfo: xfkh05pxdqswro6rljoofrz/xtbC5gsg3Wpz+astjgAA34 Content-Type: text/plain; charset="utf-8" From: Yuan Chen range_tree_clear() modifies the range tree before allocating the node needed to split a range. If the allocation fails, the function returns -ENOMEM with part of the range already removed from the tree, leaving those arena slots permanently unavailable. Pre-allocate the node before modifying the tree so a failure leaves it unmodified. Fixes: b795379757eb ("bpf: Introduce range_tree data structure and use it i= n bpf arena") Signed-off-by: Yuan Chen --- kernel/bpf/range_tree.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/range_tree.c b/kernel/bpf/range_tree.c index 2f28886f3ff7..24fa32d4356b 100644 --- a/kernel/bpf/range_tree.c +++ b/kernel/bpf/range_tree.c @@ -143,16 +143,21 @@ 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 Fri Oct 2 01:56:20 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 45E7132E728; Thu, 6 Aug 2026 03:05:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.3 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785985508; cv=none; b=esPhnYhbwPD+jEmLcq5j/1q1WXmqcg2mJyZ3AmtS8zZcUeJHXrdU3gfkJEh2jgR8SyDQiMOtlQy6SgfsVqk9OxTszSapiRGCNIMK828P7fACl/0OOyme7g6t41mFp5Foe//1UWOc6/O8luw1BMfFYYyAirfu85yPPDdbDAjRRYI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785985508; c=relaxed/simple; bh=lFyzvFLBFlFCN7WrNUZoqnrlPNPVQpdB1y4PGbHJ6Kc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NrfRpVapbaSZ/vaNf83C7Tk4J1t8Nn02sZkmeUzUsSVXceeqrgOhiRJPB3Vq6TPBDLXrdZHNOsDdjQF8CNd2YaNtphrP3Q+4ZV2t4qFrZEPVjnoh5RWW69axFZgOO0alXkcqamtlX17SqL05uAFt6QcsUiwTtBVZ35ALH6XPYXc= 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=RoPwbWG9; arc=none smtp.client-ip=220.197.31.3 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="RoPwbWG9" 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=64 vxsg4gBmXayFP7He2QEIPaG2DHX5YeIZkXH+D34FE=; b=RoPwbWG90v6vv/ObVv uss5xRb9dk9zUbqTCpygGUvqxWm6lfMMQDhRtmJde1WOVPYFESs3GzB9om/KSjwa vhEAQ4JT/jcDOZHgVKRzALVlRPv6/0iXVZWUE/2HdFugjCiydgKZoMn3KPRZWvhS rUWO4ajz9+ckEI2e8eLXZJdjY= Received: from nec8-i7 (unknown []) by gzsmtp5 (Coremail) with SMTP id QCgvCgD3Xy2m+XNqWvt+Kw--.33251S4; Thu, 06 Aug 2026 11:04:14 +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 v1 2/3] bpf, arena: fix range_tree_set inconsistency on kmalloc_nolock failure Date: Thu, 6 Aug 2026 11:03:58 +0800 Message-ID: <20260806030359.299480-3-chenyuan_fl@163.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260806030359.299480-1-chenyuan_fl@163.com> References: <20260806030359.299480-1-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: QCgvCgD3Xy2m+XNqWvt+Kw--.33251S4 X-Coremail-Antispam: 1Uf129KBjvJXoWxZr17ZFy3Wry8Wr13GFWDCFg_yoW5uF1Upw 15KrWrJrsxt3yxWrySvr48CryFkw1fXws5trZrGw4kAFn8ArZ7AFn0kF4jkFWDAFykur15 tF1jva1UGr4UuFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jbnYwUUUUU= X-CM-SenderInfo: xfkh05pxdqswro6rljoofrz/xtbC5Q4h3mpz+a5JNQAA3m Content-Type: text/plain; charset="utf-8" From: Yuan Chen range_tree_set() clears overlapping ranges before allocating the node for the new range. If the allocation fails, the function returns -ENOMEM with the cleared range already removed from the tree, leaving those arena slots permanently unavailable. Allocate only when the range has no adjacent free range on either side; this is known before the clear, since any range covering start - 1 or last + 1 survives it as an adjacent piece. A failure therefore still leaves the tree unmodified. Fixes: b795379757eb ("bpf: Introduce range_tree data structure and use it i= n bpf arena") 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 24fa32d4356b..45560e9f0d07 100644 --- a/kernel/bpf/range_tree.c +++ b/kernel/bpf/range_tree.c @@ -198,6 +198,7 @@ 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; @@ -207,20 +208,40 @@ 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 */ @@ -240,14 +261,16 @@ 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 Fri Oct 2 01:56:20 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 E9A603016FB; Thu, 6 Aug 2026 03:05:05 +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() ignore range_tree_set() errors and proceed to clear PTEs and free pages, even though the range tree still considers the range allocated. The range then becomes permanently unavailable. Check the return value: in arena_free_pages() abort the free on error; in arena_free_worker() move range_tree_set() before PTE clearing and skip the span on error. Fixes: b795379757eb ("bpf: Introduce range_tree data structure and use it i= n bpf arena") Signed-off-by: Yuan Chen --- kernel/bpf/arena.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c index 555ee2531ef9..30745da9277b 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 +1009,17 @@ 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