Re: Consistent crash of BeagleBone kernel

> On Aug 9, 2015, at 11:10 AM, Konstantin Belousov <kostikbel_at_gmail.com> wrote:
> 
> On Sun, Aug 09, 2015 at 10:53:20AM -0700, Tim Kientzle wrote:
>> 
>> I suspect the LOR is new.
>> 
>> It looks like the panic is occurring when WITNESS tries to print the backtrace for the LOR.  I???m not familiar with that code; does it use the kernel linker?
>> 
> 
> It indeed locks the linker lock to resolve symbols. So it seems to be
> even more useful to make the linker lock recursive locally, then you
> should be able to see the backtrace for LOR.

Changing the kld_sx lock to recursive, I now see a backtrace for the ufs/kernel linker LOR.  Full trace pasted below.

This is displayed just before the network interfaces; I suspect it’s being triggered when my startup initializes the urtwn wireless adapter (which does indeed load a number of kernel modules).

lock order reversal:
 1st 0xc083ef40 kernel linker (kernel linker) _at_ /Users/tim/projects/crochet/src-head/sys/kern/kern_linker.c:1030
 2nd 0xc2d63c94 ufs (ufs) _at_ /Users/tim/projects/crochet/src-head/sys/kern/vfs_lookup.c:529
KDB: stack backtrace:
db_trace_self() at db_trace_self
	 pc = 0xc0627ec0  lr = 0xc023fd34 (db_trace_self_wrapper+0x30)
	 sp = 0xde2be720  fp = 0xde2be838
	r10 = 0xc069f42b
db_trace_self_wrapper() at db_trace_self_wrapper+0x30
	 pc = 0xc023fd34  lr = 0xc03eb0ec (witness_checkorder+0xf30)
	 sp = 0xde2be840  fp = 0xde2be888
	 r4 = 0xc2725be8  r5 = 0xc2d63c94
	 r6 = 0xc06ba387  r7 = 0xc069f42b
witness_checkorder() at witness_checkorder+0xf30
	 pc = 0xc03eb0ec  lr = 0xc0375bcc (__lockmgr_args+0x24c)
	 sp = 0xde2be890  fp = 0xde2be8e8
	 r4 = 0xc2d63cb4  r5 = 0x00202400
	 r6 = 0x00000211  r7 = 0x00000000
	 r8 = 0xc2d63c94  r9 = 0x00000000
	r10 = 0xc06ba387
__lockmgr_args() at __lockmgr_args+0x24c
	 pc = 0xc0375bcc  lr = 0xc05db328 (ffs_lock+0x80)
	 sp = 0xde2be8f0  fp = 0xde2be920
	 r4 = 0xde2be948  r5 = 0x00202400
	 r6 = 0xc2d63c60  r7 = 0xc2d63c94
	 r8 = 0xc2d63cb4  r9 = 0x00000000
	r10 = 0x00000008
ffs_lock() at ffs_lock+0x80
	 pc = 0xc05db328  lr = 0xc06609ec (VOP_LOCK1_APV+0x128)
	 sp = 0xde2be928  fp = 0xde2be940
	 r4 = 0xde2be948  r5 = 0xc07a9630
	 r6 = 0x00000000  r7 = 0x00202400
	 r8 = 0xde2be948  r9 = 0x00000211
	r10 = 0xde2bed38
VOP_LOCK1_APV() at VOP_LOCK1_APV+0x128
	 pc = 0xc06609ec  lr = 0xc044dcac (_vn_lock+0x48)
	 sp = 0xde2be948  fp = 0xde2be978
	 r4 = 0xc2d63c60  r5 = 0xde2bece0
	 r6 = 0xc06ba387 r10 = 0xde2bed38
_vn_lock() at _vn_lock+0x48
	 pc = 0xc044dcac  lr = 0xc0433900 (lookup+0xf8)
	 sp = 0xde2be980  fp = 0xde2be9c8
	 r4 = 0xc2d63c60  r5 = 0xde2bece0
	 r6 = 0xde2bed50  r7 = 0x00000000
	 r8 = 0xde2bed50  r9 = 0xc306e448
	r10 = 0xde2bed38
lookup() at lookup+0xf8
	 pc = 0xc0433900  lr = 0xc0433448 (namei+0x3e8)
	 sp = 0xde2be9d0  fp = 0xde2bea48
	 r4 = 0xde2bece0  r5 = 0x00000000
	 r6 = 0xde2bed50  r7 = 0x00000000
	 r8 = 0xc2e526a0  r9 = 0xc306e448
	r10 = 0xde2bed38
namei() at namei+0x3e8
	 pc = 0xc0433448  lr = 0xc044d4b8 (vn_open_cred+0x1cc)
	 sp = 0xde2bea50  fp = 0xde2beb38
	 r4 = 0xde2bece0  r5 = 0x00000000
	 r6 = 0xc069f42d  r7 = 0x00000001
	 r8 = 0x00000000  r9 = 0x00000000
	r10 = 0xde2bed50
vn_open_cred() at vn_open_cred+0x1cc
	 pc = 0xc044d4b8  lr = 0xc044d2e4 (vn_open+0x24)
	 sp = 0xde2beb40  fp = 0xde2beb48
	 r4 = 0xde2bece0  r5 = 0xc2d0d3c0
	 r6 = 0xc069f42d  r7 = 0x0000001a
	 r8 = 0x00000000  r9 = 0xc2e526a0
	r10 = 0xc078d6f8
vn_open() at vn_open+0x24
	 pc = 0xc044d2e4  lr = 0xc0371390 (linker_load_module+0x634)
	 sp = 0xde2beb50  fp = 0xde2beda8
linker_load_module() at linker_load_module+0x634
	 pc = 0xc0371390  lr = 0xc0372ff4 (kern_kldload+0xc8)
	 sp = 0xde2bedb0  fp = 0xde2bedc8
	 r4 = 0xde2bedd4  r5 = 0xc083ef40
	 r6 = 0xc2e75000  r7 = 0x00000000
	 r8 = 0xde2bee00  r9 = 0xc306b380
	r10 = 0xbfbff5fc
kern_kldload() at kern_kldload+0xc8
	 pc = 0xc0372ff4  lr = 0xc03730bc (sys_kldload+0x64)
	 sp = 0xde2bedd0  fp = 0xde2bede8
	 r4 = 0xc2e526a0  r5 = 0xc2e75000
	 r6 = 0x00000000  r7 = 0x00000000
sys_kldload() at sys_kldload+0x64
	 pc = 0xc03730bc  lr = 0xc063e010 (swi_handler+0x2d4)
	 sp = 0xde2bedf0  fp = 0xde2bee50
	 r4 = 0xc2e526a0  r5 = 0x00000000
	 r6 = 0xc08b3d20 r10 = 0xbfbff5fc
swi_handler() at swi_handler+0x2d4
	 pc = 0xc063e010  lr = 0xc06294d8 (swi_exit)
	 sp = 0xde2bee58  fp = 0xbfbff648
	 r4 = 0x00000000  r5 = 0xbfbff600
	 r6 = 0xbfbff600  r7 = 0x00000130
	 r8 = 0xbfbff5e9  r9 = 0xbfbff5d9
	r10 = 0xbfbff5fc