Network connection does not close when network stack configured as network bridge.

[uqfus]

Lately upgraded kernel on debian linux pc from 6.12 to 6.16. And got issue: stale network connection with ksmbd if network stack configured as network bridge. On 6.12 kernel and bridge configured SMB, connection from other pc to ksmbd works fine.

I am using network bridge configuration with systemd-networkd.
10-bridge0-create.netdev

[NetDev]
Name=bridge0
Kind=bridge

20-add-enp3s0-to-bridge0.network

[Match]
Name=enp3s0

[Network]
Bridge=bridge0

30-bridge0-en.network

[Match]
Name=bridge0

[Link]
#MTUBytes=9000
Multicast=yes

[Network]
DHCP=no
Address=192.168.31.2/24
Gateway=192.168.31.1
DNS=1.1.1.1
DNS=1.0.0.1
DNSOverTLS=yes
MulticastDNS=yes
LLMNR=no
LLDP=yes

[DHCPv4]
UseDNS=no

First connection from windows pc sucessfully established and works fine. When i turn off windows pc, linux pc with ksmbd does not shutdown network conection. Connection keeps in established state.
netstat -an |grep 445

tcp6       0      0 :::445                  :::*                    LISTEN
tcp6       0      0 fe80::d078:bfff:fef:445 fe80::82b8:66f6:1:61156 ESTABLISHED
tcp6       0      0 192.168.31.2:445        192.168.31.175:51511    ESTABLISHED
tcp6       0      0 fe80::d078:bfff:fef:445 fe80::7967:540:1d:55497 ESTABLISHED

This is when only one windows pc is turned on.

Same issue with network bridge configured via ifupdown /etc/network/intefaces

Other linux PC configured without network bridge do not have same issue. Connection gracefuly closed.

Restart ksmbd or force close socket helps only one time

systemctl stop ksmbd
systemctl start ksmbd
ss -K dport 61156
ss -K dport 51511
ss -K dport 55497

[namjaejeon]

Can you tell me what minor version of 6.12 and 6.16 ? I need to check which patch cause this issue.

[uqfus]

6.16.3 6.16.7 6.16.8 all have issue.
6.12.35 6.12.30 works well
6.13.? kernel also works but exact minor version i cant tell.

[uqfus]

Just now upgraded to 6.16.9+deb14-amd64 and it seems this issue is fixed.

[namjaejeon]

There are only smb-direct(RDMA) patches between 6.16.8 and 6.16.9. I think that there may be some issue from network(/net) and fixed it with some patch. So I think that it is not ksmbd issue.

[uqfus]

6.16.9+deb14-amd64 also have same problem. Connected "net use z: \aaa.local\mnt" and lately turn off WinPC. Connection on linux PC stays in ESTABLISHED state. And on next day WinPC you can not mount drive. If before turn off WinPC do a "net use z: /delete" connection closed gracefully. Tryed "deadtime = 10" but no luck.

[mmakassikis]

Can you try with the patch I just sent on the mailing list ?

https://lore.kernel.org/linux-cifs/20251015072546.3941890-1-mmakassikis@freebox.fr/T/#u

[namjaejeon]

@mmakassikis Your patch have been applied into mainline now. (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/smb/server?id=88f170814fea74911ceab798a43cbd7c5599bed4")

@uqfus Can you check your issue with this patch ? or try 6.18-rc2 kernel that is coming soon.

[uqfus]

Will wait until debian team build kernel.
Just now checked changelog of experimental linux-image-6.17.2-amd64 (6.17.2-1~exp1) it has not pach included.