6.12-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ 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): [<ffffffff8244360e>] _raw_spin_unlock_irqrestore+0x2e/0x50 hardirqs last disabled at (972401): [<ffffffff82443328>] _raw_spin_lock_irqsave+0x18/0x60 softirqs last enabled at (972300): [<ffffffff810ffbbe>] handle_softirqs+0x3ee/0x430 softirqs last disabled at (972313): [<ffffffff810ffc54>] __irq_exit_rcu+0x44/0x110
other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rxnet->peer_hash_lock); <Interrupt> 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: <IRQ> 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 </IRQ>
Fixes: 72904d7b9bfb ("rxrpc, afs: Allow afs to pin rxrpc_peer objects") Signed-off-by: David Howells dhowells@redhat.com cc: Marc Dionne marc.dionne@auristor.com cc: Simon Horman horms@kernel.org cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/2095618.1737622752@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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); }