You may experience so called deadlocks, the situation where
system stops doing useful work. To provide the helpful bug report
in this situation, you shall use ddb as described above. Please,
include the output of ps
and
trace
for suspected processes in the
report.
If possible, consider doing further investigation. Receipt below is especially useful if you suspect deadlock occurs in the VFS layer. Add the options
makeoptions DEBUG=-g options INVARIANTS options INVARIANT_SUPPORT options WITNESS options DEBUG_LOCKS options DEBUG_VFS_LOCKS options DIAGNOSTIC
to the kernel config. When deadlock occurs, in addition to the
output of the ps
command, provide information
from the show allpcpu
, show
alllocks
, show lockedvnods
and
show alltrace
.
For threaded processes, to obtain meaningful backtraces, use
thread thread-id
to switch to the thread
stack, and do 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>.