mbuf leak found - (was mbuf leak in kernel)
By chance, would this have caused programs sending massive amounts to
syslog to block in state "objcache" on a sendmsg() call, and then
eventually hang the system with no panic? Aren't mbufs backed by
I ran into this about a couple months ago, a little while after I
updated to HEAD (right after a Preview was slipped), and I have been
meaning to take a look at it again.
I had php logging to syslog, and, only when I used a particular php
script (which wasn't even the most verbose logger), it would hang the
php processes in objcache, and when I ktrace()d the processes, they
would all hang in, I think, sendmsg(). It would start when I went to a
particular area of the web app (every single time), and once it
started, all subsequent syslog messages would hang until, after a few
minutes, the system would hang with no panic. It was strange because
it only ever happened on that one series of syslog messages.
I will try updating to see if it still happens, and if it still
happens, I will try once more to get a core for you. I had a little
trouble getting the core because it would just hang, and it took me a
while to figure out how to force a panic, and I couldn't do it from X
(it grabbed the keys), so I just haven't had a chance induce the panic
yet. I had spent half the day trying to figure out what was wrong, and
needed to move onto something else once I figured out that I could
just disable logging to syslog, and it started working again.
I'll try to check it out again tomorrow.
Updated by dillon almost 6 years ago
:By chance, would this have caused programs sending massive amounts to
:syslog to block in state "objcache" on a sendmsg() call, and then
:eventually hang the system with no panic? Aren't mbufs backed by
Yes, absolutely. Those symptoms match exactly. Any high-volume logging
to syslog can trigger the problem and can cause the process to get
stuck in objcache.
:I will try updating to see if it still happens, and if it still
:happens, I will try once more to get a core for you. I had a little
Make sure you have the latest commits, just in case you are updating
from a mirror. I posted the patches in a previous message.
:I'll try to check it out again tomorrow.
Excellent, tell me how it goes!