From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CEC3118FDDA; Wed, 5 Feb 2025 15:11:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738768311; cv=none; b=L9oAoVA2WMsCiedqu5LSJ7Ew+bdsFLTXqyIxG62ldNg9uCSZ8vAJGgtAdB8EXMdo6ACOPLSVIN2ZHWI+EYyStmo+DB7wbBOa/RRtppXjWngGVq+H+b8z9DkAom7B+WOSIhGjW2lETI2WHAC66+lsxsK9Fa3c0Ift1S7Y9dQKklc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738768311; c=relaxed/simple; bh=tKfMy8BddGnjhqUT2B3zvx7IYwh731szXMWXhBsKO/w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jY8XDPgDB7VEfxw9W8o0WPWlyUrlQf1QKiRSMVpW0me8VP8yR7HButDqOgHAT5+7ZhlcXm/YTN26+N/VQqvd50mOD7dwfL6elIrpmkFoA7zhWPyOQ2pgpNnqSl5LLlbgSeh0imfNTD5d3HA+RYh+boB4X4/jt3hF17ZjTYE6CWU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MFNRJ9JV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="MFNRJ9JV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A3C1C4CED6; Wed, 5 Feb 2025 15:11:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1738768311; bh=tKfMy8BddGnjhqUT2B3zvx7IYwh731szXMWXhBsKO/w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MFNRJ9JVN3J6uoXl3j3qXJKut7nF+TN+nR5R8lv26nTxX5vhx07s95Y88r4tZZzFz hBXoOIblUMs0bijaI2qCOMldKUHNJm/0i5B6H3ToQFgyFTwdyA/K65onEPIi03fNhp nZA9Ra9LlTeJb1VhxwYuY5ZTxEZZ0+jw4OO+kQEc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Howells , Marc Dionne , Simon Horman , linux-afs@lists.infradead.org, Jakub Kicinski , Sasha Levin Subject: [PATCH 6.13 529/623] rxrpc, afs: Fix peer hash locking vs RCU callback Date: Wed, 5 Feb 2025 14:44:31 +0100 Message-ID: <20250205134516.464436617@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250205134456.221272033@linuxfoundation.org> References: <20250205134456.221272033@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells [ Upstream commit 79d458c13056559d49b5e41fbc4b6890e68cf65b ] In its address list, afs now retains pointers to and refs on one or more rxrpc_peer objects. The address list is freed under RCU and at this time, it puts the refs on those peers. Now, when an rxrpc_peer object runs out of refs, it gets removed from the peer hash table and, for that, rxrpc has to take a spinlock. However, it is now being called from afs's RCU cleanup, which takes place in BH context - but it is just taking an ordinary spinlock. The put may also be called from non-BH context, and so there exists the possibility of deadlock if the BH-based RCU cleanup happens whilst the hash spinlock is held. This led to the attached lockdep complaint. Fix this by changing spinlocks of rxnet->peer_hash_lock back to BH-disabling locks. ================================ WARNING: inconsistent lock state 6.13.0-rc5-build2+ #1223 Tainted: G E -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff88810babe228 (&rxnet->peer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180 {SOFTIRQ-ON-W} state was registered at: mark_usage+0x164/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_peer_keepalive_worker+0x144/0x440 process_one_work+0x486/0x7c0 process_scheduled_works+0x73/0x90 worker_thread+0x1c8/0x2a0 kthread+0x19b/0x1b0 ret_from_fork+0x24/0x40 ret_from_fork_asm+0x1a/0x30 irq event stamp: 972402 hardirqs last enabled at (972402): [] _raw_spin_unlock_irqrestore+0x2e/0x50 hardirqs last disabled at (972401): [] _raw_spin_lock_irqsave+0x18/0x60 softirqs last enabled at (972300): [] handle_softirqs+0x3ee/0x430 softirqs last disabled at (972313): [] __irq_exit_rcu+0x44/0x110 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rxnet->peer_hash_lock); lock(&rxnet->peer_hash_lock); *** DEADLOCK *** 1 lock held by swapper/1/0: #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30 stack backtrace: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G E 6.13.0-rc5-build2+ #1223 Tainted: [E]=UNSIGNED_MODULE Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 Call Trace: dump_stack_lvl+0x57/0x80 print_usage_bug.part.0+0x227/0x240 valid_state+0x53/0x70 mark_lock_irq+0xa5/0x2f0 mark_lock+0xf7/0x170 mark_usage+0xe1/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_put_peer+0xcb/0x180 afs_free_addrlist+0x46/0x90 [kafs] rcu_do_batch+0x2d2/0x640 rcu_core+0x2f7/0x350 handle_softirqs+0x1ee/0x430 __irq_exit_rcu+0x44/0x110 irq_exit_rcu+0xa/0x30 sysvec_apic_timer_interrupt+0x7f/0xa0 Fixes: 72904d7b9bfb ("rxrpc, afs: Allow afs to pin rxrpc_peer objects") Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/2095618.1737622752@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/rxrpc/peer_event.c | 16 ++++++++-------- net/rxrpc/peer_object.c | 12 ++++++------ 2 files changed, 14 insertions(+), 14 deletions(-) diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index 552ba84a255c4..5d0842efde69f 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -238,7 +238,7 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet, bool use; int slot; - spin_lock(&rxnet->peer_hash_lock); + spin_lock_bh(&rxnet->peer_hash_lock); while (!list_empty(collector)) { peer = list_entry(collector->next, @@ -249,7 +249,7 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet, continue; use = __rxrpc_use_local(peer->local, rxrpc_local_use_peer_keepalive); - spin_unlock(&rxnet->peer_hash_lock); + spin_unlock_bh(&rxnet->peer_hash_lock); if (use) { keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME; @@ -269,17 +269,17 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet, */ slot += cursor; slot &= mask; - spin_lock(&rxnet->peer_hash_lock); + spin_lock_bh(&rxnet->peer_hash_lock); list_add_tail(&peer->keepalive_link, &rxnet->peer_keepalive[slot & mask]); - spin_unlock(&rxnet->peer_hash_lock); + spin_unlock_bh(&rxnet->peer_hash_lock); rxrpc_unuse_local(peer->local, rxrpc_local_unuse_peer_keepalive); } rxrpc_put_peer(peer, rxrpc_peer_put_keepalive); - spin_lock(&rxnet->peer_hash_lock); + spin_lock_bh(&rxnet->peer_hash_lock); } - spin_unlock(&rxnet->peer_hash_lock); + spin_unlock_bh(&rxnet->peer_hash_lock); } /* @@ -309,7 +309,7 @@ void rxrpc_peer_keepalive_worker(struct work_struct *work) * second; the bucket at cursor + 1 goes at now + 1s and so * on... */ - spin_lock(&rxnet->peer_hash_lock); + spin_lock_bh(&rxnet->peer_hash_lock); list_splice_init(&rxnet->peer_keepalive_new, &collector); stop = cursor + ARRAY_SIZE(rxnet->peer_keepalive); @@ -321,7 +321,7 @@ void rxrpc_peer_keepalive_worker(struct work_struct *work) } base = now; - spin_unlock(&rxnet->peer_hash_lock); + spin_unlock_bh(&rxnet->peer_hash_lock); rxnet->peer_keepalive_base = base; rxnet->peer_keepalive_cursor = cursor; diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c index 49dcda67a0d59..956fc7ea4b734 100644 --- a/net/rxrpc/peer_object.c +++ b/net/rxrpc/peer_object.c @@ -313,10 +313,10 @@ void rxrpc_new_incoming_peer(struct rxrpc_local *local, struct rxrpc_peer *peer) hash_key = rxrpc_peer_hash_key(local, &peer->srx); rxrpc_init_peer(local, peer, hash_key); - spin_lock(&rxnet->peer_hash_lock); + spin_lock_bh(&rxnet->peer_hash_lock); hash_add_rcu(rxnet->peer_hash, &peer->hash_link, hash_key); list_add_tail(&peer->keepalive_link, &rxnet->peer_keepalive_new); - spin_unlock(&rxnet->peer_hash_lock); + spin_unlock_bh(&rxnet->peer_hash_lock); } /* @@ -348,7 +348,7 @@ struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local, return NULL; } - spin_lock(&rxnet->peer_hash_lock); + spin_lock_bh(&rxnet->peer_hash_lock); /* Need to check that we aren't racing with someone else */ peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key); @@ -361,7 +361,7 @@ struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local, &rxnet->peer_keepalive_new); } - spin_unlock(&rxnet->peer_hash_lock); + spin_unlock_bh(&rxnet->peer_hash_lock); if (peer) rxrpc_free_peer(candidate); @@ -411,10 +411,10 @@ static void __rxrpc_put_peer(struct rxrpc_peer *peer) ASSERT(hlist_empty(&peer->error_targets)); - spin_lock(&rxnet->peer_hash_lock); + spin_lock_bh(&rxnet->peer_hash_lock); hash_del_rcu(&peer->hash_link); list_del_init(&peer->keepalive_link); - spin_unlock(&rxnet->peer_hash_lock); + spin_unlock_bh(&rxnet->peer_hash_lock); rxrpc_free_peer(peer); } -- 2.39.5