Re: [BUG] IMAP hibernation fails on FreeBSD 15.x with "Invalid peer_dev_major value"

Hi Timo,

Just wanted to let you know that the mail/dovecot24 port I proposed — including the hibernate patch you provided — was officially committed to the main FreeBSD ports tree today.
Thanks again for your help!

Best regards,
Jordan


> On 6 Aug 2026, at 1:31, Jordan Ostrev <[email protected]> wrote:
> 
> Hi Timo,
> I tested your patch on FreeBSD 15.x and can confirm that it completely resolves the issue.
> Test scenario:
> 
> 1. Connected via telnet localhost 143, authenticated, selected INBOX, and issued A03 IDLE.
> 2. Verified via doveadm who that after the hibernation timeout, the session successfully transitioned from imap to imap-hibernate ([email protected] 1 imap-hibernate (PID) (127.0.0.1)).
> 3. Sent a test email from an external server — the hibernated session woke up instantly, received the real-time notification (* 4297 EXISTS), and returned to the imap service without dropping the connection.
> 4. Checked the system logs — no more Invalid peer_dev_major value errors.
> 
> Everything works as expected - tested it more than once to hibernate. Thanks for the fix! 
> You can follow what happens with FreeBSD PR on https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=286695. It will be great if you can follow the thread.
> 
> KR,
> Jordan
> 
> PS.
> 
> A02 SELECT INBOX
> * FLAGS (\Answered \Flagged \Deleted \Seen \Draft unknown-1 unknown-2 unknown-4 unknown-8 unknown-5 unknown-7 unknown-3 unknown-10 $NotJunk NotJunk $Forwarded Forwarded $Junk Junk $label1 JunkRecorded $MailFlagBit0 NonJunk)
> * OK [PERMANENTFLAGS (\Answered \Flagged \Deleted \Seen \Draft unknown-1 unknown-2 unknown-4 unknown-8 unknown-5 unknown-7 unknown-3 unknown-10 $NotJunk NotJunk $Forwarded Forwarded $Junk Junk $label1 JunkRecorded $MailFlagBit0 NonJunk \*)] Flags permitted.
> * 4296 EXISTS
> * 0 RECENT
> * OK [UNSEEN 1] First unseen.
> * OK [UIDVALIDITY 1610577026] UIDs valid
> * OK [UIDNEXT 95301] Predicted next UID
> * OK [HIGHESTMODSEQ 16189] Highest
> A02 OK [READ-WRITE] Select completed (0.006 + 0.000 + 0.005 secs).
> A03 IDLE
> + idling
> * OK Still here
> * OK Still here
> * OK Still here
> * OK Still here
> * OK Still here
> * OK Still here
> * 4297 EXISTS
> * 1 RECENT
> * 4297 FETCH (FLAGS (\Recent $NotJunk NotJunk))
> * OK Still here
> * OK Still here
> * OK Still here
> * OK Still here
> * OK Still here
> * OK Still here
> 
> # doveadm who
> username            # service (pids)           (ips)
> [email protected] 3 imap    (4315 5394 3153) (46.10.221.52)
> [email protected] 1 imap-hibernate (4351)           (127.0.0.1)
> 
> # doveadm who
> username            # service (pids)                (ips)
> [email protected] 4 imap    (4315 5632 5394 3153) (46.10.221.52 127.0.0.1)
> 
> and here it goes again to hibernate 2nd time:
> # doveadm who
> username            # service (pids)                (ips)
> [email protected] 4 imap    (7247 6707 5999 3153) (46.10.221.52)
> [email protected] 1 imap-hibernate (6686)                (127.0.0.1)
> 
> 
> Telnet session never disconnected or frozen somehow.
> 
> 
> # cat /usr/ports/mail/dovecot24/files/patch-src_imap_imap-client-hibernate.c
> --- src/imap/imap-client-hibernate.c.orig	2026-08-05 21:51:45 UTC
> +++ src/imap/imap-client-hibernate.c
> @@ -62,7 +62,8 @@ static void imap_hibernate_write_cmd(struct client *cl
>  	str_append_tabescaped(cmd, user->set->unexpanded_mail_log_prefix);
>  	str_printfa(cmd, "\tidle_notify_interval=%u",
>  		    client->set->imap_idle_notify_interval);
> -	if (fstat(client->fd_in, &peer_st) == 0) {
> +	if (fstat(client->fd_in, &peer_st) == 0 &&
> +	    peer_st.st_dev != (dev_t)-1) {
>  		str_printfa(cmd, "\tpeer_dev_major=%lu\tpeer_dev_minor=%lu\tpeer_ino=%llu",
>  			    (unsigned long)major(peer_st.st_dev),
>  			    (unsigned long)minor(peer_st.st_dev),
> 
> 
> 
>> On 6 Aug 2026, at 0:46, Jordan Ostrev <[email protected]> wrote:
>> 
>> Hi,
>> 
>> I'm not a kernel developer, but I checked how FreeBSD handles socket stats (soo_stat() in sys/kern/sys_socket.c). On FreeBSD, fstat() on a socket returns st_dev = NODEV and st_ino = 0. Since st_ino is always 0 for sockets, it isn't unique or usable for verification either.
>> So your proposed patch to skip the entire check when st_dev == (dev_t)-1 is indeed the right approach.
>> 
>> KR,
>> Jordan
>> 
>> 
>>> On 5 Aug 2026, at 23:56, Timo Sirainen <[email protected]> wrote:
>>> 
>>> Hi,
>>> 
>>> I'm mainly wondering if the device is NODEV, is the inode still usable or is that also some 0 or -1? This is likely a simpler patch, but it also removes the inode check also, which isn't good if it would be usable:
>>> 
>>> diff --git a/src/imap/imap-client-hibernate.c b/src/imap/imap-client-hibernate.c
>>> index cb640c3695..191b0cfef9 100644
>>> --- a/src/imap/imap-client-hibernate.c
>>> +++ b/src/imap/imap-client-hibernate.c
>>> @@ -62,7 +62,10 @@ static void imap_hibernate_write_cmd(struct client *client, string_t *cmd,
>>>        str_append_tabescaped(cmd, user->set->unexpanded_mail_log_prefix);
>>>        str_printfa(cmd, "\tidle_notify_interval=%u",
>>>                    client->set->imap_idle_notify_interval);
>>> -       if (fstat(client->fd_in, &peer_st) == 0) {
>>> +       /* e.g. FreeBSD returns NODEV as sockets' st_dev, which can't be
>>> +          used for verifying that the fd is the expected one. */
>>> +       if (fstat(client->fd_in, &peer_st) == 0 &&
>>> +           peer_st.st_dev != (dev_t)-1) {
>>>                str_printfa(cmd, "\tpeer_dev_major=%lu\tpeer_dev_minor=%lu\tpeer_ino=%llu",
>>>                            (unsigned long)major(peer_st.st_dev),
>>>                            (unsigned long)minor(peer_st.st_dev),
>> 
>

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