LOR - 8.0-STABLE r202128

[pluknet]

2010/1/13 Gardner Bell <gbell72 at rogers.com>:
> I got this lock order reversal while running a windows executable through
> wine.

I'm guess that is a regression w.r.t S/G pager, which uses kmem_alloc/free
with vm_object locked and doesn't respect vm_map locks can sleep.
I'm curious it was back order before 5.1-R.

vm_object.c
741:        /*
742:         * Let the pager know object is dead.
743:         */
744:        vm_pager_deallocate(object);
745:        VM_OBJECT_UNLOCK(object);


>
> lock order reversal:
>  1st 0xc5e757f8 vm object (standard object) @
> /usr/src/sys/vm/vm_object.c:482
>  2nd 0xc1c900e8 system map (system map) @ /usr/src/sys/vm/vm_map.c:2772
> KDB: stack backtrace:
> db_trace_self_wrapper(c07632b0,e955d8a4,c05c7496,c05bbe7f,c076508c,...) at
> db_trace_self_wrapper+0x26
> kdb_backtrace(c05bbe7f,c076508c,c0923520,c48dd278,e955d8fc,...) at
> kdb_backtrace+0x29
> _witness_debugger(c076508c,c1c900e8,c0765236,c48d9110,c077536f,...) at
> _witness_debugger+0x1e
> witness_checkorder(c1c900e8,9,c077536f,ad4,0,...) at
> witness_checkorder+0x697
> _mtx_lock_flags(c1c900e8,0,c077536f,ad4,c6089000,...) at
> _mtx_lock_flags+0x36
> _vm_map_lock(c1c9008c,c077536f,ad4,c66437c4,c5e757f8,...) at
> _vm_map_lock+0x31
> vm_map_remove(c1c9008c,c6087000,c6089000,e955d988,c06c0417,...) at
> vm_map_remove+0x2a
> kmem_free(c1c9008c,c6087000,2000,e955d9a0,c06c1000,...) at kmem_free+0x30
> page_free(c6087000,2000,22,2000,e955d9b8,...) at page_free+0x46
> uma_large_free(c66437c4,c4ec09a4,c1c8c014,c5e757f8,e955d9c8,...) at
> uma_large_free+0x87
> free(c6087000,c07aae1c,e955d9e0,c06bb552,c6087000,...) at free+0xb8
> sglist_free(c6087000,c598d7e0,0) at sglist_free+0x28
> sg_pager_dealloc(c5e757f8,e955da14,c06d1587,c5e757f8,0,...) at
> sg_pager_dealloc+0x69
> vm_pager_deallocate(c5e757f8,0,c0775baa,2dc,0,...) at
> vm_pager_deallocate+0x1a
> vm_object_terminate(c5e757f8,0,c0775baa,1e2,e955da40,...) at
> vm_object_terminate+0x171
> vm_object_deallocate(c5e757f8,c077536f,ad7,c5548b40,0,...) at
> vm_object_deallocate+0x4ae
> _vm_map_unlock(c513d740,c077536f,ad7,1,c513d740,...) at _vm_map_unlock+0x74
> vm_map_remove(c513d740,0,bfc00000,0,c54e1550,...) at vm_map_remove+0x69
> vmspace_exit(c4ec0900,0,c075d9eb,12d,c07a6e7c,...) at vmspace_exit+0xbc
> exit1(c4ec0900,f,c0761073,b15,1,...) at exit1+0x4f3
> sigexit(c4ec0900,f,c0761073,aa5,e955dcdc,...) at sigexit+0x9f2
> postsig(f,64,c07644d3,e8,c54e1550,...) at postsig+0x1b6
> ast(e955dd38) at ast+0x308
> doreti_ast() at doreti_ast+0x17
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