Lock Order Reversal with UMA_CORE and VM_MAP

John Kintaro Tate kintarowins at gmail.com
Wed Sep 7 08:13:14 PDT 2005

I was doing a cvsup and I came across this error. This is running
7.0-CURRENT, last updated on Tuesday morning (Australia/Melbourne

exeleven# uname -a
FreeBSD exeleven.home 7.0-CURRENT FreeBSD 7.0-CURRENT #2: Tue Sep  6
11:30:56 EST 2005     root at exeleven.home:/usr/obj/usr/src/sys/GENERIC 

Here is the related output from dmesg:
lock order reversal
 1st 0xc0983ae0 UMA lock (UMA lock) @ /usr/src/sys/vm/uma_core.c:1494
 2nd 0xc1060144 system map (system map) @ /usr/src/sys/vm/vm_map.c:2317
KDB: stack backtrace:
kdb_backtrace(0,ffffffff,c0938a40,c0938b80,c08c2c84) at kdb_backtrace+0x29
witness_checkorder(c1060144,9,c0878c36,90d) at witness_checkorder+0x52c
_mtx_lock_flags(c1060144,0,c0878c36,90d) at _mtx_lock_flags+0x5b
_vm_map_lock(c10600c0,c0878c36,90d) at _vm_map_lock+0x26
vm_map_remove(c10600c0,c31aa000,c31ab000,d0ff4c0c,c07854d5) at
kmem_free(c10600c0,c31aa000,1000,d0ff4c3c,c0784e82) at kmem_free+0x25
page_free(c31aa000,1000,2) at page_free+0x29
zone_drain(c1983000) at zone_drain+0x26a
zone_foreach(c0784c18,d0ff4cec,c0796e17,d0ff4c74,246) at zone_foreach+0x37
uma_reclaim(d0ff4c74,246,0,d0ff4c80,c062c889) at uma_reclaim+0x12
vm_pageout_scan(0,c0983f40,0,c087a16b,604) at vm_pageout_scan+0x103
vm_pageout(0,d0ff4d38,0,c0797c6c,0) at vm_pageout+0x2c3
fork_exit(c0797c6c,0,d0ff4d38) at fork_exit+0xa0
fork_trampoline() at fork_trampoline+0x8
--- trap 0x1, eip = 0, esp = 0xd0ff4d6c, ebp = 0 ---

John Tate

John Kintaro Tate
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