* Re: possible deadlock in _destroy_id
2020-11-18 11:10 possible deadlock in _destroy_id syzbot
@ 2020-11-18 13:37 ` Jason Gunthorpe
2020-11-25 6:48 ` Leon Romanovsky
2020-11-18 14:26 ` syzbot
1 sibling, 1 reply; 5+ messages in thread
From: Jason Gunthorpe @ 2020-11-18 13:37 UTC (permalink / raw)
To: syzbot, leon; +Cc: dledford, linux-kernel, linux-rdma, parav, syzkaller-bugs
On Wed, Nov 18, 2020 at 03:10:21AM -0800, syzbot wrote:
> HEAD commit: 20529233 Add linux-next specific files for 20201118
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=13093cf2500000
> kernel config: https://syzkaller.appspot.com/x/.config?x=2c4fb58b6526b3c1
> dashboard link: https://syzkaller.appspot.com/bug?extid=1bc48bf7f78253f664a9
> compiler: gcc (GCC) 10.1.0-syz 20200507
>
> Unfortunately, I don't have any reproducer for this issue yet.
Oh? Is this because the error injection is too random?
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+1bc48bf7f78253f664a9@syzkaller.appspotmail.com
>
> iwpm_register_pid: Unable to send a nlmsg (client = 2)
> infiniband syz1: RDMA CMA: cma_listen_on_dev, error -98
> ============================================
> WARNING: possible recursive locking detected
> 5.10.0-rc4-next-20201118-syzkaller #0 Not tainted
> syz-executor.5/12844 is trying to acquire lock:
> ffffffff8c684748 (lock#6){+.+.}-{3:3}, at: cma_release_dev drivers/infiniband/core/cma.c:476 [inline]
> ffffffff8c684748 (lock#6){+.+.}-{3:3}, at: _destroy_id+0x299/0xa00 drivers/infiniband/core/cma.c:1852
>
> but task is already holding lock:
> ffffffff8c684748 (lock#6){+.+.}-{3:3}, at: cma_add_one+0x55c/0xce0 drivers/infiniband/core/cma.c:4902
Leon, this is caused by
commit c80a0c52d85c49a910d0dc0e342e8d8898677dc0
Author: Leon Romanovsky <leon@kernel.org>
Date: Wed Nov 4 16:40:07 2020 +0200
RDMA/cma: Add missing error handling of listen_id
Don't silently continue if rdma_listen() fails but destroy previously
created CM_ID and return an error to the caller.
rdma_destroy_id() can't be called while holding the global lock
This is quite hard to fix. I came up with this ugly thing:
From 8e6568f99fbe4bf734cc4e5dcda987e4ae118bdd Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgg@nvidia.com>
Date: Wed, 18 Nov 2020 09:33:23 -0400
Subject: [PATCH] RDMA/cma: Fix deadlock on &lock in rdma_cma_listen_on_all()
error unwind
rdma_detroy_id() cannot be called under &lock - we must instead keep the
error'd ID around until &lock can be released, then destory it.
This is complicated by the usual way listen IDs are destroyed through
cma_process_remove() which can run at any time and will asynchronously
destroy the same ID.
Remove the ID from visiblity of cma_process_remove() before going down the
destroy path outside the locking.
Fixes: c80a0c52d85c ("RDMA/cma: Add missing error handling of listen_id")
Reported-by: syzbot+1bc48bf7f78253f664a9@syzkaller.appspotmail.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/infiniband/core/cma.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 4585f654f88369..c06c87a4dc5e7d 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -2496,7 +2496,8 @@ static int cma_listen_handler(struct rdma_cm_id *id,
}
static int cma_listen_on_dev(struct rdma_id_private *id_priv,
- struct cma_device *cma_dev)
+ struct cma_device *cma_dev,
+ struct rdma_id_private **to_destroy)
{
struct rdma_id_private *dev_id_priv;
struct net *net = id_priv->id.route.addr.dev_addr.net;
@@ -2504,6 +2505,7 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv,
lockdep_assert_held(&lock);
+ *to_destroy = NULL;
if (cma_family(id_priv) == AF_IB && !rdma_cap_ib_cm(cma_dev->device, 1))
return 0;
@@ -2518,7 +2520,6 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv,
rdma_addr_size(cma_src_addr(id_priv)));
_cma_attach_to_dev(dev_id_priv, cma_dev);
- list_add_tail(&dev_id_priv->listen_list, &id_priv->listen_list);
cma_id_get(id_priv);
dev_id_priv->internal_id = 1;
dev_id_priv->afonly = id_priv->afonly;
@@ -2528,25 +2529,31 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv,
ret = rdma_listen(&dev_id_priv->id, id_priv->backlog);
if (ret)
goto err_listen;
+ list_add_tail(&dev_id_priv->listen_list, &id_priv->listen_list);
return 0;
err_listen:
- list_del(&id_priv->listen_list);
+ /* Caller must destroy this after releasing lock */
+ *to_destroy = dev_id_priv;
dev_warn(&cma_dev->device->dev, "RDMA CMA: %s, error %d\n", __func__, ret);
- rdma_destroy_id(&dev_id_priv->id);
return ret;
}
static int cma_listen_on_all(struct rdma_id_private *id_priv)
{
+ struct rdma_id_private *to_destroy;
struct cma_device *cma_dev;
int ret;
mutex_lock(&lock);
list_add_tail(&id_priv->list, &listen_any_list);
list_for_each_entry(cma_dev, &dev_list, list) {
- ret = cma_listen_on_dev(id_priv, cma_dev);
- if (ret)
+ ret = cma_listen_on_dev(id_priv, cma_dev, &to_destroy);
+ if (ret) {
+ /* Prevent racing with cma_process_remove() */
+ if (to_destroy)
+ list_del_init(&to_destroy->list);
goto err_listen;
+ }
}
mutex_unlock(&lock);
return 0;
@@ -2554,6 +2561,8 @@ static int cma_listen_on_all(struct rdma_id_private *id_priv)
err_listen:
list_del(&id_priv->list);
mutex_unlock(&lock);
+ if (to_destroy)
+ rdma_destroy_id(&to_destroy->id);
return ret;
}
@@ -4855,6 +4864,7 @@ static void cma_process_remove(struct cma_device *cma_dev)
static int cma_add_one(struct ib_device *device)
{
+ struct rdma_id_private *to_destroy;
struct cma_device *cma_dev;
struct rdma_id_private *id_priv;
unsigned int i;
@@ -4902,7 +4912,7 @@ static int cma_add_one(struct ib_device *device)
mutex_lock(&lock);
list_add_tail(&cma_dev->list, &dev_list);
list_for_each_entry(id_priv, &listen_any_list, list) {
- ret = cma_listen_on_dev(id_priv, cma_dev);
+ ret = cma_listen_on_dev(id_priv, cma_dev, &to_destroy);
if (ret)
goto free_listen;
}
@@ -4915,6 +4925,7 @@ static int cma_add_one(struct ib_device *device)
list_del(&cma_dev->list);
mutex_unlock(&lock);
+ /* cma_process_remove() will delete to_destroy */
cma_process_remove(cma_dev);
kfree(cma_dev->default_roce_tos);
free_gid_type:
--
2.29.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: possible deadlock in _destroy_id
2020-11-18 11:10 possible deadlock in _destroy_id syzbot
2020-11-18 13:37 ` Jason Gunthorpe
@ 2020-11-18 14:26 ` syzbot
1 sibling, 0 replies; 5+ messages in thread
From: syzbot @ 2020-11-18 14:26 UTC (permalink / raw)
To: dledford, jgg, leon, linux-kernel, linux-rdma, parav, syzkaller-bugs
syzbot has found a reproducer for the following issue on:
HEAD commit: 20529233 Add linux-next specific files for 20201118
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16ce97be500000
kernel config: https://syzkaller.appspot.com/x/.config?x=2c4fb58b6526b3c1
dashboard link: https://syzkaller.appspot.com/bug?extid=1bc48bf7f78253f664a9
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10b53981500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10e94c7e500000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1bc48bf7f78253f664a9@syzkaller.appspotmail.com
wlan1 speed is unknown, defaulting to 1000
iwpm_register_pid: Unable to send a nlmsg (client = 2)
infiniband syz2: RDMA CMA: cma_listen_on_dev, error -98
============================================
WARNING: possible recursive locking detected
5.10.0-rc4-next-20201118-syzkaller #0 Not tainted
--------------------------------------------
syz-executor872/8502 is trying to acquire lock:
ffffffff8c684748 (lock#6){+.+.}-{3:3}, at: cma_release_dev drivers/infiniband/core/cma.c:476 [inline]
ffffffff8c684748 (lock#6){+.+.}-{3:3}, at: _destroy_id+0x299/0xa00 drivers/infiniband/core/cma.c:1852
but task is already holding lock:
ffffffff8c684748 (lock#6){+.+.}-{3:3}, at: cma_add_one+0x55c/0xce0 drivers/infiniband/core/cma.c:4902
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(lock#6);
lock(lock#6);
*** DEADLOCK ***
May be due to missing lock nesting notation
6 locks held by syz-executor872/8502:
#0: ffffffff8fa76958 (&rdma_nl_types[idx].sem){.+.+}-{3:3}, at: rdma_nl_rcv_msg+0x15b/0x690 drivers/infiniband/core/netlink.c:164
#1: ffffffff8c66c490 (link_ops_rwsem){++++}-{3:3}, at: nldev_newlink+0x261/0x540 drivers/infiniband/core/nldev.c:1545
#2: ffffffff8c65bd90 (devices_rwsem){++++}-{3:3}, at: enable_device_and_get+0xfc/0x3c0 drivers/infiniband/core/device.c:1321
#3: ffffffff8c65bc50 (clients_rwsem){++++}-{3:3}, at: enable_device_and_get+0x163/0x3c0 drivers/infiniband/core/device.c:1331
#4: ffff888026f28598 (&device->client_data_rwsem){++++}-{3:3}, at: add_client_context+0x3d0/0x5e0 drivers/infiniband/core/device.c:710
#5: ffffffff8c684748 (lock#6){+.+.}-{3:3}, at: cma_add_one+0x55c/0xce0 drivers/infiniband/core/cma.c:4902
stack backtrace:
CPU: 1 PID: 8502 Comm: syz-executor872 Not tainted 5.10.0-rc4-next-20201118-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
print_deadlock_bug kernel/locking/lockdep.c:2759 [inline]
check_deadlock kernel/locking/lockdep.c:2802 [inline]
validate_chain kernel/locking/lockdep.c:3593 [inline]
__lock_acquire.cold+0x115/0x39f kernel/locking/lockdep.c:4830
lock_acquire kernel/locking/lockdep.c:5435 [inline]
lock_acquire+0x2a3/0x8c0 kernel/locking/lockdep.c:5400
__mutex_lock_common kernel/locking/mutex.c:956 [inline]
__mutex_lock+0x134/0x1110 kernel/locking/mutex.c:1103
cma_release_dev drivers/infiniband/core/cma.c:476 [inline]
_destroy_id+0x299/0xa00 drivers/infiniband/core/cma.c:1852
cma_listen_on_dev.cold+0x168/0x16d drivers/infiniband/core/cma.c:2535
cma_add_one+0x667/0xce0 drivers/infiniband/core/cma.c:4905
add_client_context+0x405/0x5e0 drivers/infiniband/core/device.c:712
enable_device_and_get+0x1d5/0x3c0 drivers/infiniband/core/device.c:1333
ib_register_device drivers/infiniband/core/device.c:1408 [inline]
ib_register_device+0x7a0/0xa30 drivers/infiniband/core/device.c:1367
siw_device_register drivers/infiniband/sw/siw/siw_main.c:72 [inline]
siw_newlink drivers/infiniband/sw/siw/siw_main.c:545 [inline]
siw_newlink+0xddb/0x1340 drivers/infiniband/sw/siw/siw_main.c:522
nldev_newlink+0x30e/0x540 drivers/infiniband/core/nldev.c:1555
rdma_nl_rcv_msg+0x367/0x690 drivers/infiniband/core/netlink.c:195
rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
rdma_nl_rcv+0x2f2/0x440 drivers/infiniband/core/netlink.c:259
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:650 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:670
____sys_sendmsg+0x6e8/0x810 net/socket.c:2339
___sys_sendmsg+0xf3/0x170 net/socket.c:2393
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2426
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x440339
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff91ac9ae8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440339
RDX: 0000000000000000 RSI: 00000000200002c0 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000014 R09: 00000000004002c8
R10: 0000000000000041 R11: 0000000000000246 R12: 0000000000401b40
R13: 0000000000401bd0 R14: 0000000000000000 R15: 0000000000000000
^ permalink raw reply [flat|nested] 5+ messages in thread