From: Cheng Lin <cheng.lin130@xxxxxxxxxx>
[ Upstream commit 4a9d81caf841cd2c0ae36abec9c2963bf21d0284 ]
If the elem is deleted during be iterated on it, the iteration
process will fall into an endless loop.
kernel: NMI watchdog: BUG: soft lockup - CPU#4 stuck for 22s! [nfsd:17137]
PID: 17137 TASK: ffff8818d93c0000 CPU: 4 COMMAND: "nfsd"
[exception RIP: __state_in_grace+76]
RIP: ffffffffc00e817c RSP: ffff8818d3aefc98 RFLAGS: 00000246
RAX: ffff881dc0c38298 RBX: ffffffff81b03580 RCX: ffff881dc02c9f50
RDX: ffff881e3fce8500 RSI: 0000000000000001 RDI: ffffffff81b03580
RBP: ffff8818d3aefca0 R8: 0000000000000020 R9: ffff8818d3aefd40
R10: ffff88017fc03800 R11: ffff8818e83933c0 R12: ffff8818d3aefd40
R13: 0000000000000000 R14: ffff8818e8391068 R15: ffff8818fa6e4000
CS: 0010 SS: 0018
#0 [ffff8818d3aefc98] opens_in_grace at ffffffffc00e81e3 [grace]
#1 [ffff8818d3aefca8] nfs4_preprocess_stateid_op at ffffffffc02a3e6c [nfsd]
#2 [ffff8818d3aefd18] nfsd4_write at ffffffffc028ed5b [nfsd]
#3 [ffff8818d3aefd80] nfsd4_proc_compound at ffffffffc0290a0d [nfsd]
#4 [ffff8818d3aefdd0] nfsd_dispatch at ffffffffc027b800 [nfsd]
#5 [ffff8818d3aefe08] svc_process_common at ffffffffc02017f3 [sunrpc]
#6 [ffff8818d3aefe70] svc_process at ffffffffc0201ce3 [sunrpc]
#7 [ffff8818d3aefe98] nfsd at ffffffffc027b117 [nfsd]
#8 [ffff8818d3aefec8] kthread at ffffffff810b88c1
#9 [ffff8818d3aeff50] ret_from_fork at ffffffff816d1607
The troublemake elem:
crash> lock_manager ffff881dc0c38298
struct lock_manager {
list = {
next = 0xffff881dc0c38298,
prev = 0xffff881dc0c38298
},
block_opens = false
}
Fixes: c87fb4a378f9 ("lockd: NLM grace period shouldn't block NFSv4 opens")
Signed-off-by: Cheng Lin <cheng.lin130@xxxxxxxxxx>
Signed-off-by: Yi Wang <wang.yi59@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/nfs_common/grace.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/nfs_common/grace.c b/fs/nfs_common/grace.c
index 77d136ac89099..c21fca0dcba74 100644
--- a/fs/nfs_common/grace.c
+++ b/fs/nfs_common/grace.c
@@ -75,10 +75,14 @@ __state_in_grace(struct net *net, bool open)
if (!open)
return !list_empty(grace_list);
+ spin_lock(&grace_lock);
list_for_each_entry(lm, grace_list, list) {
- if (lm->block_opens)
+ if (lm->block_opens) {
+ spin_unlock(&grace_lock);
return true;
+ }
}
+ spin_unlock(&grace_lock);
return false;
}
--
2.27.0
