DIAGNOSTIC LOR in softclock

Poul-Henning Kamp phk at phk.freebsd.dk
Sat Nov 15 10:36:24 PST 2003

This looks slightly different if I use SCHED_ULE, but the effect is
the same.

Off the top of my head, I have not been able to find any places
where softclock would call schedcpu directly.

Suspect locking foobar.

Suggest more people us DIAGNOSTIC


ata2-slave: FAILURE - SETFEATURES status=51<READY,DSC,ERROR> error=4<ABORTED>
acd0: CDROM <665A> at ata2-slave BIOSPIO
acd1: CDROM <SAMSUNG SC-148P> at ata3-master PIO4
lock order reversal
 1st 0xc072dca0 callout_dont_sleep (callout_dont_sleep) @ kern/kern_timeout.c:223
 2nd 0xc072d080 allproc (allproc) @ kern/sched_4bsd.c:257
Stack backtrace:
backtrace(c06d148d,c072d080,c06cd881,c06cd881,c06cf38b) at backtrace+0x17
witness_lock(c072d080,0,c06cf38b,101,c5061c3c) at witness_lock+0x672
_sx_slock(c072d080,c06cf382,101,8,c06cf0a0) at _sx_slock+0xae
schedcpu(0,0,c06cf097,df,c1183140) at schedcpu+0x3f
softclock(0,0,c06cbce6,23a,c1189388) at softclock+0x1fb
ithread_loop(c1180400,c5061d48,c06cbb54,311,558b0424) at ithread_loop+0x192
fork_exit(c050b090,c1180400,c5061d48) at fork_exit+0xb5
fork_trampoline() at fork_trampoline+0x8
--- trap 0x1, eip = 0, esp = 0xc5061d7c, ebp = 0 ---

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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