Re: [PATCH 12/14] cifs: handle when server stops supporting multichannel

Shyam Prasad N
2023-11-09T11:44:57Z

On Thu, Nov 9, 2023 at 1:11 AM Paulo Alcantara <pc@manguebit.com> wrote:
>
> > and leaked server connections
> >
> > Display Internal CIFS Data Structures for Debugging
> > ---------------------------------------------------
> > CIFS Version 2.46
> > Features: DFS,FSCACHE,STATS2,DEBUG2,ALLOW_INSECURE_LEGACY,CIFS_POSIX,UPCALL(SPNEGO),XATTR,ACL,WITNESS
> > CIFSMaxBufSize: 16384
> > Active VFS Requests: 0
> >
> > Servers:
> > 1) ConnectionId: 0x70e Hostname: w22-root2.gandalf.test
> > ClientGUID: 44DAE383-3E91-3042-85FE-87D6F17298B7
> > Number of credits: 1,1,1 Dialect 0x210
> > Server capabilities: 0x300007
> > TCP status: 4 Instance: 77
> > Local Users To Server: 1 SecMode: 0x1 Req On Wire: 0 Net namespace: 4026531840
> > In Send: 0 In MaxReq Wait: 0
> > DFS leaf full path: \\W22-ROOT1.GANDALF.TEST\dfstest3\link10
> >
> > Sessions:
> > [NONE]
> > 2) ConnectionId: 0x706 Hostname: w22-root2.gandalf.test
> > ClientGUID: C8CF45E4-F70D-DF40-8821-0234A2E20DD4
> > Number of credits: 1,1,1 Dialect 0x210
> > Server capabilities: 0x300007
> > TCP status: 4 Instance: 81
> > Local Users To Server: 1 SecMode: 0x1 Req On Wire: 0 Net namespace: 4026531840
> > In Send: 0 In MaxReq Wait: 0
> > DFS leaf full path: \\W22-ROOT1.GANDALF.TEST\dfstest3\link6
> >
> > Sessions:
> > [NONE]
> > 3) ConnectionId: 0x6ae Hostname: w22-root1.gandalf.test
> > ClientGUID: AB059CDD-12FF-B94D-B30C-9E1928ACBA95
> > Number of credits: 1,1,1 Dialect 0x210
> > Server capabilities: 0x300007
> > TCP status: 4 Instance: 96
> > Local Users To Server: 1 SecMode: 0x1 Req On Wire: 0 Net namespace: 4026531840
> > In Send: 0 In MaxReq Wait: 0
> > DFS leaf full path: \\W22-ROOT1.GANDALF.TEST\dfstest3\link9
> >
> > Sessions:
> > [NONE]
> > ...
>
> I ended up with a simple reproducer for the above
>
> mount.cifs //srv/share /mnt/1 -o ...,echo_interval=10
> iptables -I INPUT -s $srvaddr -j DROP
> stat -f /mnt/1
> # check dmesg for "BUG: sleeping function called from invalid context"
> iptables -I INPUT -s $srvaddr -j ACCEPT
> stat -f /mnt/1
> umount /mnt/1
> # check /proc/fs/cifs/DebugData for leaked server connection

Ack. I'll try and get a repro locally and debug this one.

--
Regards,
Shyam