Date: Fri, 8 Mar 2002 19:02:40 -0500 (EST) From: Robert Watson <rwatson@freebsd.org> To: David Wolfskill <david@catwhisker.org> Cc: current@freebsd.org Subject: Re: Keyboard (quasi-)lockup running script Message-ID: <Pine.NEB.3.96L.1020308185221.91006C-100000@fledge.watson.org> In-Reply-To: <Pine.NEB.3.96L.1020308181553.91006A-100000@fledge.watson.org>
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Some more details, now I have WITNESS compiled in... crash1# script ls Script started, output file is ls crash1# crash1# exitStopped at siointr1+0xf2: movl $0,brk_state1.702 db> trace siointr1(c185f400,c0446ec0,0,c03a0260,662) at siointr1+0xf2 siointr(c185f400,18,c86c0010,c0230010,0) at siointr+0x23 Xfastintr4() at Xfastintr4+0x32 --- interrupt, eip = 0xc0329e52, esp = 0xc86cad14, ebp = 0xc86cad14 --- cpu_idle(c86cad34,c0228798,0,c86cad48,0) at cpu_idle+0x1e idle_proc(0,c86cad48,0,c02288f4,0) at idle_proc+0x21 fork_exit(c02288f4,0,c86cad48) at fork_exit+0x98 fork_trampoline() at fork_trampoline+0x8 db> ps pid proc addr uid ppid pgrp flag stat wmesg wchan cmd 193 c9722c00 c975a000 0 192 193 0006002 3 ttywai c1b1c674 csh 192 c8cf2600 c9728000 0 189 192 0004002 3 pgrpsess c03dc0fc script 189 c8cf2300 c972e000 0 188 189 2004002 3 pause c972e000 csh 188 c9722f00 c9749000 0 1 188 0004102 3 wait c9722f00 login ... db> trace 192 mi_switch(c03dc0e0,c03dc0fc,78a,c0385a20,14f) at mi_switch+0x17c cv_wait(c03dc0fc,c0413564,c8cf2600,c18be400,0) at cv_wait+0x1fb _sx_slock(c03dc0e0,c03873e0,78a,0,c91b78a0) at _sx_slock+0x5c ttwrite(c18be400,c972bc90,6e0001,c0410360,c972bbf8) at ttwrite+0xa4 siowrite(c0410360,c972bc90,6e0001,c0410360,3) at siowrite+0x78 spec_write(c972bc24,c972bc38,c027d9a7,c972bc24,3) at spec_write+0x5d spec_vnoperate(c972bc24,3,c972bd20,0,1) at spec_vnoperate+0x15 vn_write(c1b1bd40,c972bc90,c1b1fb00,0,c8cf2700) at vn_write+0x1a3 dofilewrite(c8cf2700,c1b1bd40,1,bfbff790,3) at dofilewrite+0xb6 write(c8cf2700,c972bd20,0,4,11) at write+0x51 syscall(2f,2f,2f,11,4) at syscall+0x21f syscall_with_err_pushed() at syscall_with_err_pushed+0x1b --- syscall (4, FreeBSD ELF, write), eip = 0x280c3fd7, esp = 0xbfbff2cc, ebp = 0xbfbffc18 --- db> show locks exclusive (spin mutex) sio (0xc0446ec0) locked @ /cboss/p4/rwatson/trustedbsd/mac/sys/dev/sio/sio.c:1634 I suspect, unfortunately, that that is only my kernel debugger entry point. So, here's what happens if I do it using a pty for the script session, keeping the kernel debugger out of the picture: (pty0) crash1# script ls Script started, output file is ls crash1# exit (serial console) pid proc addr uid ppid pgrp flag stat wmesg wchan cmd 194 c973a900 c975f000 0 193 194 0006002 3 ttywai c1b28674 csh 193 c8cf2900 c971b000 0 190 193 0004002 3 pgrpsess c03dc0fc script 190 c8cf2600 c9728000 0 189 190 2004002 3 pause c9728000 csh 189 c8cf2300 c972e000 0 156 156 0000000 3 select c03de548 sshd 188 c973ac00 c9754000 0 1 188 0004002 3 pgrpsess c03dc0fc getty 187 c973af00 c974f000 0 1 187 0004002 3 ttyin c1b0b610 getty ... db> trace 193 # script mi_switch(c03dc0e0,c03dc0fc,78a,c0385a20,14f) at mi_switch+0x17c cv_wait(c03dc0fc,c0413564,c8cf2900,c1b0b228,0) at cv_wait+0x1fb _sx_slock(c03dc0e0,c03873e0,78a,c1b1c600,c96f3620) at _sx_slock+0x5c ttwrite(c1b0b228,c971ec90,620001,c971ebf8,c0212d79) at ttwrite+0xa4 ptswrite(c1b1c600,c971ec90,620001,c1b1c600,3) at ptswrite+0x28 spec_write(c971ec24,c971ec38,c027d9a7,c971ec24,3) at spec_write+0x5d spec_vnoperate(c971ec24,3,c971ed20,0,1) at spec_vnoperate+0x15 vn_write(c1af2100,c971ec90,c0b2db00,0,c8cf2a00) at vn_write+0x1a3 dofilewrite(c8cf2a00,c1af2100,1,bfbff73c,3) at dofilewrite+0xb6 write(c8cf2a00,c971ed20,0,4,11) at write+0x51 syscall(2f,2f,2f,11,4) at syscall+0x21f syscall_with_err_pushed() at syscall_with_err_pushed+0x1b --- syscall (4, FreeBSD ELF, write), eip = 0x280c3fd7, esp = 0xbfbff278, ebp = 0xbfbffbc4 --- db> trace 188 # getty mi_switch(c03dc0e0,c03dc0fc,78a,c0385a20,14f) at mi_switch+0x17c cv_wait(c03dc0fc,c0413564,c973ac00,c18be400,0) at cv_wait+0x1fb _sx_slock(c03dc0e0,c03873e0,78a,0,c91b78a0) at _sx_slock+0x5c ttwrite(c18be400,c9757c90,40001,c0410360,c9757bf8) at ttwrite+0xa4 siowrite(c0410360,c9757c90,40001,c0410360,1) at siowrite+0x78 spec_write(c9757c24,c9757c38,c027d9a7,c9757c24,1) at spec_write+0x5d spec_vnoperate(c9757c24,1,c9757d20,0,1) at spec_vnoperate+0x15 vn_write(c1b1bf80,c9757c90,c1b1cc00,0,c973ad00) at vn_write+0x1a3 dofilewrite(c973ad00,c1b1bf80,1,8050680,1) at dofilewrite+0xb6 write(c973ad00,c9757d20,bfbffde4,805072c,80507cc) at write+0x51 syscall(2f,2f,2f,80507cc,805072c) at syscall+0x21f syscall_with_err_pushed() at syscall_with_err_pushed+0x1b --- syscall (4, FreeBSD ELF, write), eip = 0x280c7fd7, esp = 0xbfbffcf0, ebp = 0xbfbffd0c --- So perhaps there's a deadlock. Or at least, it looks like both processes hang trying to get a shared lock for the session, and block waiting. Perhaps the lock is getting corrupted somehow, or has not properly been initialized? Unfortunately, it looks like 'show locks' only knows about the mutex in the sio code, presumably from the serial debugger: db> show locks exclusive (spin mutex) sio (0xc0446ec0) locked @ /cboss/p4/rwatson/trustedbsd/mac/sys/dev/sio/sio.c:1634 Does 'show locks' not show sxlocks? I was pretty sure it did... Robert N M Watson FreeBSD Core Team, TrustedBSD Project robert@fledge.watson.org NAI Labs, Safeport Network Services To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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