Product: Gigabyte Technology Co., Ltd., B150N Phoenix-WIFI-CF, B150N Phoenix-WIFI
ARCH: x86_64
CPU: 4 x Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz
RAM: 7915 MiB
System: Deepin 20 Beta, n/a
Kernel: Linux 5.3.0-3-amd64
Docker: Docker version 19.03.8, build afacb8b7f0
Shell: /bin/bash 5.0.3(1)-release

Product: Hasee, HM65, QTH6
ARCH: x86_64
CPU: 8 x Intel(R) Core(TM) i7-2670QM CPU @ 2.20GHz
RAM: 7908 MiB
System: Ubuntu 20.04 LTS, focal
Kernel: Linux 5.4.0-29-generic
Docker: Docker version 19.03.8, build afacb8b7f0
Shell: /bin/bash 5.0.16(1)-release

http://showterm.io/7683579af57bf70fcdcbb

[  298.582552] Oops: 0002 [#1] SMP PTI
[  298.582554] CPU: 3 PID: 6373 Comm: modprobe Not tainted 5.4.0-29-generic #33-Ubuntu
[  298.582555] Hardware name: Hasee QTH6/HM65, BIOS SU272 12/16/2011
[  298.582568] RIP: 0010:nfsd_fill_super+0x72/0x90 [nfsd]
[  298.582570] Code: 89 c4 85 c0 74 0a 5b 44 89 e0 41 5c 41 5d 5d c3 48 8b 7b 68 31 f6 48 c7 c2 e3 75 0e c1 e8 96 fe ff ff 48 3d 00 f0 ff ff 77 0e <49> 89 45 58 44 89 e0 5b 41 5c 41 5d 5d c3 41 89 c4 eb c9 66 66 2e
[  298.582571] RSP: 0018:ffffb13a4343ba90 EFLAGS: 00010287
[  298.582572] RAX: ffff9a6e9c20b0c0 RBX: ffff9a6ec5543800 RCX: 0000000000000002
[  298.582574] RDX: 0000000000000000 RSI: 0000000000000100 RDI: ffff9a6e9c295ac0
[  298.582575] RBP: ffffb13a4343baa8 R08: ffff9a6e9c20b0e0 R09: 0000000000000000
[  298.582576] R10: 0000000000000000 R11: fefefefefefefeff R12: 0000000000000000
[  298.582577] R13: 0000000000000000 R14: ffffffffc10abf10 R15: 0000000000000000
[  298.582578] FS:  00007f28c3160740(0000) GS:ffff9a6ef78c0000(0000) knlGS:0000000000000000
[  298.582579] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  298.582581] CR2: 0000000000000058 CR3: 0000000201c1e004 CR4: 00000000000606e0
[  298.582582] Call Trace:
[  298.582587]  vfs_get_super+0x7f/0x100
[  298.582590]  get_tree_keyed+0x1a/0x20
[  298.582599]  nfsd_fs_get_tree+0x23/0x30 [nfsd]
[  298.582601]  vfs_get_tree+0x2a/0xc0
[  298.582603]  fc_mount+0x13/0x50
[  298.582605]  vfs_kern_mount.part.0+0x78/0x90
[  298.582607]  vfs_kern_mount+0x13/0x20
[  298.582615]  nfsd_init_net+0x11f/0x150 [nfsd]
[  298.582617]  ops_init+0x42/0x100
[  298.582619]  register_pernet_operations+0xee/0x1e0
[  298.582620]  register_pernet_subsys+0x29/0x40
[  298.582632]  ? trace_event_define_fields_nfsd_file_fsnotify_handle_event+0xb4/0xb4 [nfsd]
[  298.582642]  init_nfsd+0x23/0x8ba [nfsd]
[  298.582653]  ? trace_event_define_fields_nfsd_file_fsnotify_handle_event+0xb4/0xb4 [nfsd]
[  298.582655]  do_one_initcall+0x4a/0x1fa
[  298.582657]  ? kfree+0x224/0x240
[  298.582659]  ? _cond_resched+0x19/0x30
[  298.582661]  ? kmem_cache_alloc_trace+0x163/0x230
[  298.582663]  do_init_module+0x62/0x250
[  298.582665]  load_module+0x10b8/0x1200
[  298.582669]  __do_sys_finit_module+0xbe/0x120
[  298.582671]  ? __do_sys_finit_module+0xbe/0x120
[  298.582673]  __x64_sys_finit_module+0x1a/0x20
[  298.582675]  do_syscall_64+0x57/0x190
[  298.582677]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  298.582679] RIP: 0033:0x7f28c2c803c9
[  298.582681] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 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 73 01 c3 48 8b 0d 8f 9a 2c 00 f7 d8 64 89 01 48
[  298.582682] RSP: 002b:00007ffca1e956d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[  298.582684] RAX: ffffffffffffffda RBX: 00005626e2264ee9 RCX: 00007f28c2c803c9
[  298.582685] RDX: 0000000000000000 RSI: 00005626e2264ee9 RDI: 0000000000000003
[  298.582686] RBP: 0000000000000000 R08: 0000000000000000 R09: 00005626e286f240
[  298.582687] R10: 0000000000000003 R11: 0000000000000246 R12: 00005626e2867290
[  298.582688] R13: 00005626e286ab60 R14: 00005626e286f390 R15: 0000000000040000
[  298.582689] Modules linked in: nfsd(+) auth_rpcgss nfs_acl lockd grace sunrpc binfmt_misc 9pnet_virtio 9pnet minix xt_nat xt_tcpudp veth xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xfrm_user xfrm_algo xt_addrtype iptable_filter iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c bpfilter br_netfilter bridge stp llc aufs ccm overlay nls_iso8859_1 intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic uvcvideo ledtrig_audio kvm_intel videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 ath9k videobuf2_common kvm videodev mc ath9k_common crct10dif_pclmul ghash_clmulni_intel ath9k_hw snd_hda_intel ath aesni_intel snd_intel_dspcfg nouveau snd_hda_codec mac80211 crypto_simd mei_hdcp cryptd glue_helper snd_seq_midi snd_seq_midi_event snd_rawmidi cfg80211 libarc4 ttm i915 snd_seq snd_hda_core mei_me snd_hwdep snd_pcm mei intel_cstate intel_rapl_perf lg_laptop snd_seq_device
[  298.582713]  snd_timer drm_kms_helper snd i2c_algo_bit fb_sys_fops syscopyarea soundcore sysfillrect sysimgblt sparse_keymap mxm_wmi wmi_bmof input_leds mac_hid serio_raw sch_fq_codel parport_pc ppdev lp parport drm ip_tables x_tables autofs4 ums_realtek uas usb_storage hid_generic usbhid hid crc32_pclmul ahci psmouse lpc_ich libahci i2c_i801 atl1c wmi video
[  298.582726] CR2: 0000000000000058
[  298.582728] ---[ end trace 92a2bff8887bc92b ]---
[  298.582737] RIP: 0010:nfsd_fill_super+0x72/0x90 [nfsd]
[  298.582738] Code: 89 c4 85 c0 74 0a 5b 44 89 e0 41 5c 41 5d 5d c3 48 8b 7b 68 31 f6 48 c7 c2 e3 75 0e c1 e8 96 fe ff ff 48 3d 00 f0 ff ff 77 0e <49> 89 45 58 44 89 e0 5b 41 5c 41 5d 5d c3 41 89 c4 eb c9 66 66 2e
[  298.582739] RSP: 0018:ffffb13a4343ba90 EFLAGS: 00010287
[  298.582741] RAX: ffff9a6e9c20b0c0 RBX: ffff9a6ec5543800 RCX: 0000000000000002
[  298.582742] RDX: 0000000000000000 RSI: 0000000000000100 RDI: ffff9a6e9c295ac0
[  298.582743] RBP: ffffb13a4343baa8 R08: ffff9a6e9c20b0e0 R09: 0000000000000000
[  298.582744] R10: 0000000000000000 R11: fefefefefefefeff R12: 0000000000000000
[  298.582745] R13: 0000000000000000 R14: ffffffffc10abf10 R15: 0000000000000000
[  298.582746] FS:  00007f28c3160740(0000) GS:ffff9a6ef78c0000(0000) knlGS:0000000000000000
[  298.582747] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  298.582748] CR2: 0000000000000058 CR3: 0000000201c1e004 CR4: 00000000000606e0

https://github.com/docker/for-linux/issues/996

commit 681370f4b00af0fcc65bbfb9f82de526ab7ceb0a
Author: J. Bruce Fields <bfields@redhat.com>
Date:   Tue Jun 23 16:00:33 2020 -0400

    nfsd4: fix nfsdfs reference count loop
    
    We don't drop the reference on the nfsdfs filesystem with
    mntput(nn->nfsd_mnt) until nfsd_exit_net(), but that won't be called
    until the nfsd module's unloaded, and we can't unload the module as long
    as there's a reference on nfsdfs.  So this prevents module unloading.
    
    Fixes: 2c830dd7209b ("nfsd: persist nfsd filesystem across mounts")
    Reported-and-Tested-by:  Luo Xiaogang <lxgrxd@163.com>
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index bb3d2c3..cce2510 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7912,9 +7912,14 @@ static int nfs4_state_create_net(struct net *net)
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 	int ret;
 
-	ret = nfs4_state_create_net(net);
+	ret = get_nfsdfs(net);
 	if (ret)
 		return ret;
+	ret = nfs4_state_create_net(net);
+	if (ret) {
+		mntput(nn->nfsd_mnt);
+		return ret;
+	}
 	locks_start_grace(net, &nn->nfsd4_manager);
 	nfsd4_client_tracking_init(net);
 	if (nn->track_reclaim_completes && nn->reclaim_str_hashtbl_size == 0)
@@ -7984,6 +7989,7 @@ static int nfs4_state_create_net(struct net *net)
 
 	nfsd4_client_tracking_exit(net);
 	nfs4_state_destroy_net(net);
+	mntput(nn->nfsd_mnt);
 }
 
 void
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index b68e966..cf98a81 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1424,6 +1424,18 @@ static void nfsd_umount(struct super_block *sb)
 };
 MODULE_ALIAS_FS("nfsd");
 
+int get_nfsdfs(struct net *net)
+{
+	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+	struct vfsmount *mnt;
+
+	mnt =  vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL);
+	if (IS_ERR(mnt))
+		return PTR_ERR(mnt);
+	nn->nfsd_mnt = mnt;
+	return 0;
+}
+
 #ifdef CONFIG_PROC_FS
 static int create_proc_exports_entry(void)
 {
@@ -1451,7 +1463,6 @@ static int create_proc_exports_entry(void)
 static __net_init int nfsd_init_net(struct net *net)
 {
 	int retval;
-	struct vfsmount *mnt;
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 
 	retval = nfsd_export_init(net);
@@ -1478,16 +1489,8 @@ static __net_init int nfsd_init_net(struct net *net)
 	init_waitqueue_head(&nn->ntf_wq);
 	seqlock_init(&nn->boot_lock);
 
-	mnt =  vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL);
-	if (IS_ERR(mnt)) {
-		retval = PTR_ERR(mnt);
-		goto out_mount_err;
-	}
-	nn->nfsd_mnt = mnt;
 	return 0;
 
-out_mount_err:
-	nfsd_reply_cache_shutdown(nn);
 out_drc_error:
 	nfsd_idmap_shutdown(net);
 out_idmap_error:
@@ -1500,7 +1503,6 @@ static __net_exit void nfsd_exit_net(struct net *net)
 {
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 
-	mntput(nn->nfsd_mnt);
 	nfsd_reply_cache_shutdown(nn);
 	nfsd_idmap_shutdown(net);
 	nfsd_export_shutdown(net);
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 36cdd81..57c832d 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -90,6 +90,8 @@ struct readdir_cd {
 
 bool		i_am_nfsd(void);
 
+int get_nfsdfs(struct net *);
+
 struct nfsdfs_client {
 	struct kref cl_ref;
 	void (*cl_release)(struct kref *kref);
@@ -100,6 +102,7 @@ struct dentry *nfsd_client_mkdir(struct nfsd_net *nn,
 		struct nfsdfs_client *ncl, u32 id, const struct tree_descr *);
 void nfsd_client_rmdir(struct dentry *dentry);
 
+
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 #ifdef CONFIG_NFSD_V2_ACL
 extern const struct svc_version nfsd_acl_version2;