You may experience so called deadlocks, the situation where
a system stops doing useful work. To provide a helpful bug report
in this situation, use ddb(4) as described above.
Include the output of ps
and
trace
for suspected processes in the
report.
If possible, consider doing further investigation. The receipt below is especially useful if you suspect that a deadlock occurs in the VFS layer. Add the following options
makeoptions DEBUG=-g options INVARIANTS options INVARIANT_SUPPORT options WITNESS options WITNESS_SKIPSPIN options DEBUG_LOCKS options DEBUG_VFS_LOCKS options DIAGNOSTIC
to the kernel configuration file. When a deadlock occurs, in addition to the
output of the ps
command, provide information
from the show pcpu
, show allpcpu
,
show locks
, show alllocks
,
show lockedvnods
and alltrace
.
To obtain meaningful backtraces for threaded processes, use
thread thread-id
to switch to the thread
stack, and do a backtrace with where
.
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Questions that are not answered by the
documentation may be
sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.