Hi,
I had a 6.6 machine where a lot of git processes got stuck sleeping
on "futex". The process holding the futex rwlock was this one.
33293 332235 1 2734 3 0x800483 fsleep git
It called mi_switch() from proc_stop() with this trace.
issignal(ffff80002acc74a8) at issignal+0x2ec
sleep_setup_signal(120,ffffffff81e2e168) at sleep_setup_signal+0xdf
rwsleep(12d8,ffff80002acc74a8,23,c010e7fabd0,0) at rwsleep+0x94
futex_wait(2,ffff80002b0fb480,c010e7fabd0,12d8) at futex_wait+0x180
sys_futex(530,ffff80002acc74a8,53) at sys_futex+0x80
syscall(0) at syscall+0x37d
Xsyscall(0,53,0,53,0,c015a954200) at Xsyscall+0x128
So I would say the process was stopped instead of sleeping and did
not release the lock. Can rwsleep() call rw_exit() before
sleep_setup_signal()? This diff survived a full make regress on
amd64.
ok?
bluhm
Index: kern/kern_synch.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/kern/kern_synch.c,v
retrieving revision 1.162
diff -u -p -r1.162 kern_synch.c
--- kern/kern_synch.c 30 Jan 2020 08:51:27 -0000 1.162
+++ kern/kern_synch.c 1 Mar 2020 12:11:30 -0000
@@ -320,9 +320,9 @@ rwsleep(const volatile void *ident, stru
sleep_setup(&sls, ident, priority, wmesg);
sleep_setup_timeout(&sls, timo);
- sleep_setup_signal(&sls);
-
rw_exit(rwl);
+ /* signal may stop the process, release rwlock before that */
+ sleep_setup_signal(&sls);
error = sleep_finish_all(&sls, 1);
