> > 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 } This part (and a similar loop during shutting down the demultiplex thread) is the only place where we add/remove to the ->qhead list without holding the GlobalMid_Lock. I wonder if it is racing against a different thread also modifying qhead for the same mid, like cifs_delete_mid() for example. ----- Original Message ----- > From: "Ronnie Sahlberg" <lsahlber@xxxxxxxxxx> > To: "David Wysochanski" <dwysocha@xxxxxxxxxx> > Cc: "linux-cifs" <linux-cifs@xxxxxxxxxxxxxxx>, "Frank Sorenson" <sorenson@xxxxxxxxxx> > Sent: Thursday, 17 October, 2019 10:17:18 AM > Subject: Re: list_del corruption while iterating retry_list in cifs_reconnect still seen on 5.4-rc3 > > I can not reproduce this :-( > > I have run it for a few hours, restarting samba in a loop with up to 30 > threads. > > > Can you check > 1, If this only reproduce for you for the root of the share or it also > reproduces for a subdirectory? > 2, Does it reproduce also if you use "nohandlecache" mount option? > This disables the use of cached open of the root handle, i.e. > open_shroot() > 3, When this happens, can you check the content of the mid entry and what > these fields are: > mid->mid_flags, mid->handle (this is a function pointer, what does it > point to) > mid->command. Maybe print the whole structure. > > regards > ronnie sahlberg > > > > > ----- Original Message ----- > > From: "David Wysochanski" <dwysocha@xxxxxxxxxx> > > To: "linux-cifs" <linux-cifs@xxxxxxxxxxxxxxx> > > Cc: "Frank Sorenson" <sorenson@xxxxxxxxxx> > > Sent: Thursday, 17 October, 2019 5:27:02 AM > > Subject: list_del corruption while iterating retry_list in cifs_reconnect > > still seen on 5.4-rc3 > > > > 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); > > >