Date: Mon, 27 Dec 2021 13:39:11 +0100 From: Jan Mikkelsen <janm@transactionware.com> To: freebsd-hackers@freebsd.org Subject: closefrom blocking, wchan urdlck Message-ID: <2B3BA665-D42A-4B5F-AD2F-ED10E64A7276@transactionware.com>
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Hi,
(On 11.2)
I am occasionally seeing closefrom() block in a child process created by =
a call to pdfork().
When this does happen, it is very early after the process has started, =
while other threads are being created elsewhere in the process. I cannot =
reproduce it after the thread creation is complete. According to the =
sigaction man page, this should be async signal safe.
Stack trace from the call to closefrom():
* frame #0: 0x000000080090276c libthr.so.3`_umtx_op_err at =
_umtx_op_err.S:37
frame #1: 0x00000008008f6121 =
libthr.so.3`__thr_rwlock_rdlock(rwlock=3D<unavailable>, =
flags=3D<unavailable>, tsp=3D<unavailable>) at thr_umtx.c:307:10
frame #2: 0x00000008008ff1ac libthr.so.3`_thr_rtld_rlock_acquire =
[inlined] _thr_rwlock_rdlock(rwlock=3D0x0000000800911600, flags=3D0, =
tsp=3D0x0000000000000000) at thr_umtx.h:232:10
frame #3: 0x00000008008ff19b =
libthr.so.3`_thr_rtld_rlock_acquire(lock=3D0x0000000800911600) at =
thr_rtld.c:125
frame #4: 0x000000080075332b =
ld-elf.so.1`rlock_acquire(lock=3D0x0000000800765270, =
lockstate=3D0x00007fffdfbfb8d0) at rtld_lock.c:208:2
frame #5: 0x000000080074ba20 =
ld-elf.so.1`_rtld_bind(obj=3D0x0000000800769000, reloff=3D6072) at =
rtld.c:861:5
frame #6: 0x0000000800747c7d ld-elf.so.1`_rtld_bind_start at =
rtld_start.S:121
frame #7: 0x00000000006562d3 =
prog`Twio::ProcHandle::spawn(this=3D<unavailable>, command=3D"/bin/echo", =
args=3D0x0000000800d7e000, descriptor_mapping=3D<unavailable>, =
descriptor_end=3D3) at prochandle_pdfork.cpp:308:2
Any suggestions on how to approach this?
Regards,
Jan M.
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