I think this has been there for a long time, since we first saw this
on a 4.18.0 based kernel but I just noticed the bug recently.
I just retested on 5.4-rc3 and it's still there. Easy to repro with a
fairly simple but invasive server restart test - takes only maybe a
couple minutes on my VM.
>From Frank Sorenson:
mount off a samba server:
# mount //vm1/share /mnt/vm1
-overs=2.1,hard,sec=ntlmssp,credentials=/root/.smb_creds
on the client, start 10 'find' loops:
# export test_path=/mnt/vm1
# do_find() { while true ; do find $test_path >/dev/null 2>&1 ; done }
# for i in {1..10} ; do do_find & done
optional: also start something to monitor for when the hang occurs:
# while true ; do count=$(grep smb2_reconnect /proc/*/stack -A3 |
grep -c open_shroot) ; [[ $count -gt 0 ]] && { echo "$(date):
reproduced bug" ; break ; } ; echo "$(date): stayin' alive" ; sleep 2
; done
On the samba server: restart smb.service (loop it in case it requires
more than one restart):
# while true ; do echo "$(date): restarting" ; systemctl restart
smb.service ; sleep 5 ; done | tee /var/tmp/smb_restart_log.out
[ 430.454897] list_del corruption. prev->next should be
ffff98d3a8f316c0, but was 2e885cb266355469
[ 430.464668] ------------[ cut here ]------------
[ 430.466569] kernel BUG at lib/list_debug.c:51!
[ 430.468476] invalid opcode: 0000 [#1] SMP PTI
[ 430.470286] CPU: 0 PID: 13267 Comm: cifsd Kdump: loaded Not tainted
5.4.0-rc3+ #19
[ 430.473472] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[ 430.475872] RIP: 0010:__list_del_entry_valid.cold+0x31/0x55
[ 430.478129] Code: 5e 15 8e e8 54 a3 c5 ff 0f 0b 48 c7 c7 78 5f 15
8e e8 46 a3 c5 ff 0f 0b 48 89 f2 48 89 fe 48 c7 c7 38 5f 15 8e e8 32
a3 c5 ff <0f> 0b 48 89 fe 4c 89 c2 48 c7 c7 00 5f 15 8e e8 1e a3 c5 ff
0f 0b
[ 430.485563] RSP: 0018:ffffb4db0042fd38 EFLAGS: 00010246
[ 430.487665] RAX: 0000000000000054 RBX: ffff98d3aabb8800 RCX: 0000000000000000
[ 430.490513] RDX: 0000000000000000 RSI: ffff98d3b7a17908 RDI: ffff98d3b7a17908
[ 430.493383] RBP: ffff98d3a8f316c0 R08: ffff98d3b7a17908 R09: 0000000000000285
[ 430.496258] R10: ffffb4db0042fbf0 R11: ffffb4db0042fbf5 R12: ffff98d3aabb89c0
[ 430.499113] R13: ffffb4db0042fd48 R14: 2e885cb266355469 R15: ffff98d3b24c4480
[ 430.501981] FS: 0000000000000000(0000) GS:ffff98d3b7a00000(0000)
knlGS:0000000000000000
[ 430.505232] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 430.507546] CR2: 00007f08cd17b9c0 CR3: 000000023484a000 CR4: 00000000000406f0
[ 430.510426] Call Trace:
[ 430.511500] cifs_reconnect+0x25e/0x610 [cifs]
[ 430.513350] cifs_readv_from_socket+0x220/0x250 [cifs]
[ 430.515464] cifs_read_from_socket+0x4a/0x70 [cifs]
[ 430.517452] ? try_to_wake_up+0x212/0x650
[ 430.519122] ? cifs_small_buf_get+0x16/0x30 [cifs]
[ 430.521086] ? allocate_buffers+0x66/0x120 [cifs]
[ 430.523019] cifs_demultiplex_thread+0xdc/0xc30 [cifs]
[ 430.525116] kthread+0xfb/0x130
[ 430.526421] ? cifs_handle_standard+0x190/0x190 [cifs]
[ 430.528514] ? kthread_park+0x90/0x90
[ 430.530019] ret_from_fork+0x35/0x40
[ 430.531487] Modules linked in: cifs libdes libarc4 ip6t_rpfilter
ip6t_REJECT nf_reject_ipv6 xt_conntrack ebtable_nat ip6table_nat
ip6table_mangle ip6table_raw ip6table_security iptable_nat nf_nat
iptable_mangle iptable_raw iptable_security nf_conntrack
nf_defrag_ipv6 nf_defrag_ipv4 ip_set nfnetlink ebtable_filter ebtables
ip6table_filter ip6_tables crct10dif_pclmul crc32_pclmul joydev
virtio_balloon ghash_clmulni_intel i2c_piix4 nfsd nfs_acl lockd
auth_rpcgss grace sunrpc xfs libcrc32c virtio_net net_failover
crc32c_intel virtio_console serio_raw virtio_blk ata_generic failover
pata_acpi qemu_fw_cfg
[ 430.552782] ---[ end trace c91d4468f8689482 ]---
[ 430.554948] RIP: 0010:__list_del_entry_valid.cold+0x31/0x55
[ 430.557251] Code: 5e 15 8e e8 54 a3 c5 ff 0f 0b 48 c7 c7 78 5f 15
8e e8 46 a3 c5 ff 0f 0b 48 89 f2 48 89 fe 48 c7 c7 38 5f 15 8e e8 32
a3 c5 ff <0f> 0b 48 89 fe 4c 89 c2 48 c7 c7 00 5f 15 8e e8 1e a3 c5 ff
0f 0b
[ 430.565019] RSP: 0018:ffffb4db0042fd38 EFLAGS: 00010246
[ 430.567181] RAX: 0000000000000054 RBX: ffff98d3aabb8800 RCX: 0000000000000000
[ 430.570073] RDX: 0000000000000000 RSI: ffff98d3b7a17908 RDI: ffff98d3b7a17908
[ 430.572955] RBP: ffff98d3a8f316c0 R08: ffff98d3b7a17908 R09: 0000000000000285
[ 430.575854] R10: ffffb4db0042fbf0 R11: ffffb4db0042fbf5 R12: ffff98d3aabb89c0
[ 430.578745] R13: ffffb4db0042fd48 R14: 2e885cb266355469 R15: ffff98d3b24c4480
[ 430.581624] FS: 0000000000000000(0000) GS:ffff98d3b7a00000(0000)
knlGS:0000000000000000
[ 430.584881] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 430.587230] CR2: 00007f08cd17b9c0 CR3: 000000023484a000 CR4: 00000000000406f0
crash> dis -lr cifs_reconnect+0x25e | tail --lines=20
0xffffffffc062dc26 <cifs_reconnect+0x226>: movb
$0x0,0xbb36b(%rip) # 0xffffffffc06e8f98 <GlobalMid_Lock>
/mnt/build/kernel/fs/cifs/connect.c: 572
0xffffffffc062dc2d <cifs_reconnect+0x22d>: mov %r12,%rdi
0xffffffffc062dc30 <cifs_reconnect+0x230>: callq
0xffffffff8d9d5a20 <mutex_unlock>
/mnt/build/kernel/fs/cifs/connect.c: 574
0xffffffffc062dc35 <cifs_reconnect+0x235>: testb
$0x1,0xbb300(%rip) # 0xffffffffc06e8f3c <cifsFYI>
0xffffffffc062dc3c <cifs_reconnect+0x23c>: je
0xffffffffc062dc43 <cifs_reconnect+0x243>
/mnt/build/kernel/./arch/x86/include/asm/jump_label.h: 25
0xffffffffc062dc3e <cifs_reconnect+0x23e>: data32 data32 data32
xchg %ax,%ax
/mnt/build/kernel/fs/cifs/connect.c: 575
0xffffffffc062dc43 <cifs_reconnect+0x243>: mov 0x8(%rsp),%rbp
0xffffffffc062dc48 <cifs_reconnect+0x248>: mov 0x0(%rbp),%r14
0xffffffffc062dc4c <cifs_reconnect+0x24c>: cmp %r13,%rbp
0xffffffffc062dc4f <cifs_reconnect+0x24f>: jne
0xffffffffc062dc56 <cifs_reconnect+0x256>
0xffffffffc062dc51 <cifs_reconnect+0x251>: jmp
0xffffffffc062dc90 <cifs_reconnect+0x290>
0xffffffffc062dc53 <cifs_reconnect+0x253>: mov %rax,%r14
/mnt/build/kernel/./include/linux/list.h: 190
0xffffffffc062dc56 <cifs_reconnect+0x256>: mov %rbp,%rdi
0xffffffffc062dc59 <cifs_reconnect+0x259>: callq
0xffffffff8d4e6b00 <__list_del_entry_valid>
0xffffffffc062dc5e <cifs_reconnect+0x25e>: test %al,%al
fs/cifs/connect.c
566 mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
567 if (mid_entry->mid_state == MID_REQUEST_SUBMITTED)
568 mid_entry->mid_state = MID_RETRY_NEEDED;
569 list_move(&mid_entry->qhead, &retry_list);
570 }
571 spin_unlock(&GlobalMid_Lock);
572 mutex_unlock(&server->srv_mutex);
573
574 cifs_dbg(FYI, "%s: issuing mid callbacks\n", __func__);
575--> list_for_each_safe(tmp, tmp2, &retry_list) {
576 mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
577 list_del_init(&mid_entry->qhead);
578 mid_entry->callback(mid_entry);
579 }
580
581 if (cifs_rdma_enabled(server)) {
582 mutex_lock(&server->srv_mutex);
583 smbd_destroy(server);
584 mutex_unlock(&server->srv_mutex);
