Re: [regression 6.1.76] dlm: cannot start dlm midcomms -97 after backport of e9cdebbe23f1 ("dlm: use kernel_connect() and kernel_bind()")

[Salvatore Bonaccorso]

Hi Alexander,

On Wed, Feb 07, 2024 at 04:27:48PM -0500, Alexander Aring wrote:
> Hi,
> 
> On Wed, Feb 7, 2024 at 1:33 PM Jordan Rife <jrife@xxxxxxxxxx> wrote:
> >
> > On Wed, Feb 7, 2024 at 2:39 AM Salvatore Bonaccorso <carnil@xxxxxxxxxx> wrote:
> > >
> > > Hi Valentin, hi all
> > >
> > > [This is about a regression reported in Debian for 6.1.67]
> > >
> > > On Tue, Feb 06, 2024 at 01:00:11PM +0100, Valentin Kleibel wrote:
> > > > Package: linux-image-amd64
> > > > Version: 6.1.76+1
> > > > Source: linux
> > > > Source-Version: 6.1.76+1
> > > > Severity: important
> > > > Control: notfound -1 6.6.15-2
> > > >
> > > > Dear Maintainers,
> > > >
> > > > We discovered a bug affecting dlm that prevents any tcp communications by
> > > > dlm when booted with debian kernel 6.1.76-1.
> > > >
> > > > Dlm startup works (corosync-cpgtool shows the dlm:controld group with all
> > > > expected nodes) but as soon as we try to add a lockspace dmesg shows:
> > > > ```
> > > > dlm: Using TCP for communications
> > > > dlm: cannot start dlm midcomms -97
> > > > ```
> > > >
> > > > It seems that commit "dlm: use kernel_connect() and kernel_bind()"
> > > > (e9cdebbe) was merged to 6.1.
> > > >
> > > > Checking the code it seems that the changed function dlm_tcp_listen_bind()
> > > > fails with exit code 97 (EAFNOSUPPORT)
> > > > It is called from
> > > >
> > > > dlm/lockspace.c: threads_start() -> dlm_midcomms_start()
> > > > dlm/midcomms.c: dlm_midcomms_start() -> dlm_lowcomms_start()
> > > > dlm/lowcomms.c: dlm_lowcomms_start() -> dlm_listen_for_all() ->
> > > > dlm_proto_ops->listen_bind() = dlm_tcp_listen_bind()
> > > >
> > > > The error code is returned all the way to threads_start() where the error
> > > > message is emmitted.
> > > >
> > > > Booting with the unsigned kernel from testing (6.6.15-2), which also
> > > > contains this commit, works without issues.
> > > >
> > > > I'm not sure what additional changes are required to get this working or if
> > > > rolling back this change is an option.
> > > >
> > > > We'd be happy to test patches that might fix this issue.
> > >
> > > Thanks for your report. So we have a 6.1.76 specific regression for
> > > the backport of e9cdebbe23f1 ("dlm: use kernel_connect() and
> > > kernel_bind()") .
> > >
> > > Let's loop in the upstream regression list for tracking and people
> > > involved for the subsystem to see if the issue can be identified. As
> > > it is working for 6.6.15 which includes the commit backport as well it
> > > might be very well that a prerequisite is missing.
> > >
> > > # annotate regression with 6.1.y specific commit
> > > #regzbot ^introduced e11dea8f503341507018b60906c4a9e7332f3663
> > > #regzbot link: https://bugs.debian.org/1063338
> > >
> > > Any ideas?
> > >
> > > Regards,
> > > Salvatore
> >
> >
> > Just a quick look comparing dlm_tcp_listen_bind between the latest 6.1
> > and 6.6 stable branches,
> > it looks like there is a mismatch here with the dlm_local_addr[0] parameter.
> >
> > 6.1
> > ----
> >
> > static int dlm_tcp_listen_bind(struct socket *sock)
> > {
> > int addr_len;
> >
> > /* Bind to our port */
> > make_sockaddr(dlm_local_addr[0], dlm_config.ci_tcp_port, &addr_len);
> > return kernel_bind(sock, (struct sockaddr *)&dlm_local_addr[0],
> >    addr_len);
> > }
> >
> > 6.6
> > ----
> > static int dlm_tcp_listen_bind(struct socket *sock)
> > {
> > int addr_len;
> >
> > /* Bind to our port */
> > make_sockaddr(&dlm_local_addr[0], dlm_config.ci_tcp_port, &addr_len);
> > return kernel_bind(sock, (struct sockaddr *)&dlm_local_addr[0],
> >    addr_len);
> > }
> >
> > 6.6 contains commit c51c9cd8 (fs: dlm: don't put dlm_local_addrs on heap) which
> > changed
> >
> > static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
> >
> > to
> >
> > static struct sockaddr_storage dlm_local_addr[DLM_MAX_ADDR_COUNT];
> >
> > It looks like kernel_bind() in 6.1 needs to be modified to match.
> >
> 
> makes sense. I tried to cherry-pick e9cdebbe23f1 ("dlm: use
> kernel_connect() and kernel_bind()") on v6.1.67 as I don't see it
> there. It failed and does not apply cleanly.
> 
> Are we talking here about a debian kernel specific backport? If so,
> maybe somebody missed to modify those parts you mentioned.

Thanks all for looking into it.

No it's not a Debian specific backport, e9cdebbe23f1 ("dlm: use
kernel_connect() and kernel_bind()") got in fact backported upstream
in 6.1.76, 6.6.15 and 6.7.3. The respective commits are:

v6.1.76: e11dea8f503341507018b60906c4a9e7332f3663 dlm: use kernel_connect() and kernel_bind()
v6.6.15: c018ab3e31b16ff97b9b95b69904104c9fcca95b dlm: use kernel_connect() and kernel_bind()
v6.7.3: 4ecf1864f2076872b7aea29d463e785ef6fc9909 dlm: use kernel_connect() and kernel_bind()
v6.8-rc1: e9cdebbe23f1aa9a1caea169862f479ab3fa2773 dlm: use kernel_connect() and kernel_bind()

But for the 6.1.76 case there is the above regression (while it works
for 6.6.15 as confirmed by the reporter).

I'm very sorry I see where I have caused you confusion: The regression
is in 6.1.*76* not 6.1.*67* and I misstyped the version in two places.

Regards,
Salvatore