Date: Fri, 8 Jan 2021 21:32:15 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Vasily Postnicov <shamaz.mazum@gmail.com> Cc: Mark Johnston <markj@freebsd.org>, freebsd-net@freebsd.org Subject: Re: DNS using Name Service Switch module and Casper Message-ID: <X/izP6G03eOSN/Ph@kib.kiev.ua> In-Reply-To: <CADnZ6Bm96bjJN5gcpCWiNKbNou3XvxZmCD2-YbX34%2B00L=UdPw@mail.gmail.com> References: <CADnZ6Bke=9%2B_pMc6rkbheNUWS-H6_X14%2Bf%2BWz5cfUCD=BTwk=g@mail.gmail.com> <X/R7Ahz8sz5v%2BoFa@raichu> <CADnZ6BmUJxVZx155j8opJKNsHJBE5mWz9D=MBE0Y_xu-kgOBfQ@mail.gmail.com> <X/h%2BJRmXmrOfmXBM@raichu> <CADnZ6Bm96bjJN5gcpCWiNKbNou3XvxZmCD2-YbX34%2B00L=UdPw@mail.gmail.com>
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On Fri, Jan 08, 2021 at 08:17:25PM +0300, Vasily Postnicov wrote: > I have noticed that after I kill stuck ping, the process spawned with > cap_init() remains. I cannot even kill it with SIGKILL. This is the > output of procstat on such a process. > > > vasily 969 0.0 0.1 26428 6532 v0 I 22:43 0:00.00 ping > vonbraun.local > vasily 983 0.0 0.1 26428 6532 v0 I 22:43 0:00.00 ping > resurrected.local > vasily 1024 0.0 0.1 26428 6532 v0 I 22:49 0:00.00 ping > resurrected.local > vasily 1028 0.0 0.1 26428 6532 v0 I 22:49 0:00.00 ping > resurrected.local > root 1089 0.0 0.0 12976 2512 v1 S+ 22:58 0:00.01 grep ping > PID TID COMM TDNAME KSTACK > 1028 100579 ping - mi_switch+0x155 > sleepq_switch+0x109 sleepq_catch_signals+0x266 sleepq_wait_sig+0x9 > _sleep+0x2aa umtxq_sleep+0x19e do_lock_umutex+0x744 > __umtx_op_wait_umutex+0x49 sys__umtx_op+0x7a amd64_syscall+0x12e > fast_syscall_common+0xf8 This is strange, I sprinkled enough checks for stops and kills into kern_umtx:do_lock_*(), I believe. Also, if there is kill pending, sleepq_catch_signal() should not remove the thread from runq. I would expect that there is such bug if this thread went into loop with 100% CPU usage, but by your report it sleeps. Could it be that you need to kill ping from root? If killing from root does not help: What is the kernel version? Can you provide minimal standalone binary that reproduces this situation? I do not even need sources, binary alone which does not use any libraries not from base, is enough.
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