Date: Thu, 12 Aug 2004 10:27:41 -0700 From: Nate Lawson <nate@root.org> To: Alan Cox <alc@cs.rice.edu> Cc: current@freebsd.org Subject: Re: LoR aironet/VM subsystem Message-ID: <411BA88D.6070000@root.org> In-Reply-To: <20040812054959.GF3527@cs.rice.edu> References: <411B0226.3030806@root.org> <20040812054959.GF3527@cs.rice.edu>
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Alan Cox wrote: > On Wed, Aug 11, 2004 at 10:37:42PM -0700, Nate Lawson wrote: > >>an0: <Cisco Systems 340 Series Wireless LAN Adapter> at port >>0x2000-0x203f irq 11 function 0 config 5 on pccard1 >>an0: got RSSI <-> dBM map >>an0: supported rates: 1Mbps 2Mbps 5.5Mbps 11Mbps >>an0: Ethernet address: 00:40:96:42:91:c5 >>an0: [GIANT-LOCKED] >>lock order reversal >> 1st 0xc163339c an0 (network driver) @ dev/an/if_an.c:1931 >> 2nd 0xc134b164 user map (user map) @ vm/vm_map.c:2902 >>KDB: stack backtrace: >>kdb_backtrace(0,ffffffff,c0696d88,c0697a08,c066630c) at kdb_backtrace+0x29 >>witness_checkorder(c134b164,9,c06469a0,b56) at witness_checkorder+0x544 >>_sx_xlock(c134b164,c0646997,b56) at _sx_xlock+0x50 >>_vm_map_lock_read(c134b128,c0646997,b56,1b69978,c1402e4c) at >>_vm_map_lock_read+0x33 >>vm_map_lookup(d0b69a10,bfbfd000,1,d0b69a14,d0b69a04) at vm_map_lookup+0x28 >>vm_fault(c134b128,bfbfd000,1,0,c1371840) at vm_fault+0x66 >>trap_pfault(d0b69ad8,0,bfbfd000) at trap_pfault+0xd2 >>trap(c04f0018,c06b0010,c1630010,c1633df4,bfbfd000) at trap+0x311 >>calltrap() at calltrap+0x5 >>--- trap 0xc, eip = 0xc060661e, esp = 0xd0b69b18, ebp = 0xd0b69ba4 --- >>generic_copyin(c1632000,c020693a,d0b69c60,c04d4b78,c06bb8e0) at >>generic_copyin+0x32 >>ifhwioctl(c020693a,c1632000,d0b69c60,c1371840,c0698048) at ifhwioctl+0x854 >>ifioctl(c16219e0,c020693a,d0b69c60,c1371840,0) at ifioctl+0xbd >>soo_ioctl(c158f440,c020693a,d0b69c60,c133c480,c1371840) at soo_ioctl+0x2b1 >>ioctl(c1371840,d0b69d14,3,2,292) at ioctl+0x3e0 >>syscall(2f,2f,2f,3,bfbfef64) at syscall+0x217 >>Xint0x80_syscall() at Xint0x80_syscall+0x1f >>--- syscall (54, FreeBSD ELF32, ioctl), eip = 0x280d0083, esp = >>0xbfbfad7c, ebp = 0xbfbfadb8 --- >> > > This looks like a programming error in the driver. Specifically, > the driver is calling copyin() while holding a mutex. That's not > allowed because of the potential for a page fault that sleeps. It is. AN_LOCK is held over the entire contents of an_ioctl(). This function is so huge, it's unclear how to reduce the scope of this lock. -Nate
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