link down work may be scheduled before lgr freed but execute
after lgr freed, which may result in crash. So it is need to
hold a reference before shedule link down work, and put the
reference after work executed or canceled.
The relevant crash call stack as follows:
list_del corruption. prev->next should be ffffb638c9c0fe20,
but was 0000000000000000
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:51!
invalid opcode: 0000 [#1] SMP NOPTI
CPU: 6 PID: 978112 Comm: kworker/6:119 Kdump: loaded Tainted: G #1
Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 2221b89 04/01/2014
Workqueue: events smc_link_down_work [smc]
RIP: 0010:__list_del_entry_valid.cold+0x31/0x47
RSP: 0018:ffffb638c9c0fdd8 EFLAGS: 00010086
RAX: 0000000000000054 RBX: ffff942fb75e5128 RCX: 0000000000000000
RDX: ffff943520930aa0 RSI: ffff94352091fc80 RDI: ffff94352091fc80
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffb638c9c0fc38
R10: ffffb638c9c0fc30 R11: ffffffffa015eb28 R12: 0000000000000002
R13: ffffb638c9c0fe20 R14: 0000000000000001 R15: ffff942f9cd051c0
FS: 0000000000000000(0000) GS:ffff943520900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4f25214000 CR3: 000000025fbae004 CR4: 00000000007706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
rwsem_down_write_slowpath+0x17e/0x470
smc_link_down_work+0x3c/0x60 [smc]
process_one_work+0x1ac/0x350
worker_thread+0x49/0x2f0
? rescuer_thread+0x360/0x360
kthread+0x118/0x140
? __kthread_bind_mask+0x60/0x60
ret_from_fork+0x1f/0x30
Fixes: 541afa10c126 ("net/smc: add smcr_port_err() and smcr_link_down() processing")
Signed-off-by: Guangguan Wang <guangguan.wang@xxxxxxxxxxxxxxxxx>
Reviewed-by: Tony Lu <tonylu@xxxxxxxxxxxxxxxxx>
---
net/smc/smc_core.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 500952c2e67b..3b125d348b4a 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1818,7 +1818,9 @@ void smcr_link_down_cond_sched(struct smc_link *lnk)
{
if (smc_link_downing(&lnk->state)) {
trace_smcr_link_down(lnk, __builtin_return_address(0));
- schedule_work(&lnk->link_down_wrk);
+ smcr_link_hold(lnk); /* smcr_link_put in link_down_wrk */
+ if (!schedule_work(&lnk->link_down_wrk))
+ smcr_link_put(lnk);
}
}
@@ -1850,11 +1852,14 @@ static void smc_link_down_work(struct work_struct *work)
struct smc_link_group *lgr = link->lgr;
if (list_empty(&lgr->list))
- return;
+ goto out;
wake_up_all(&lgr->llc_msg_waiter);
down_write(&lgr->llc_conf_mutex);
smcr_link_down(link);
up_write(&lgr->llc_conf_mutex);
+
+out:
+ smcr_link_put(link); /* smcr_link_hold by schedulers of link_down_work */
}
static int smc_vlan_by_tcpsk_walk(struct net_device *lower_dev,
--
2.24.3 (Apple Git-128)
