Date: Wed, 24 Sep 1997 16:32:08 +0900 From: KATO Takenori <kato@migmatite.eps.nagoya-u.ac.jp> To: dg@root.com Cc: current@FreeBSD.ORG Subject: Re: Daily SNAPshots at current.freebsd.org shut down for now. Message-ID: <199709240732.QAA00371@gneiss.eps.nagoya-u.ac.jp> In-Reply-To: Your message of "Tue, 23 Sep 1997 22:15:22 -0700" References: <199709240515.WAA20124@implode.root.com>
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> What is wrong with using LK_CANRECURSE ? In any case, the exact cause
> of the recursive locking needs to be understood before this sort of change
> is made.
I received kgdb log (that is, I don't have vmcore).
The backtrace shows that vnstrategy is called twice:
1. vnstrategy() locks the vnode.
2. vnstrategy() calls ffs_write().
3. cluster write stuff calls vnstrategy() again.
4. Because the vnode has been already locked, VOP_LOCK/vn_lock
causes recursive lock.
I think problem is in cluster write stuff. It may expect fs stuff
supports reentrance, but vnode fs expect it is not reentered.
So, possible fixes are:
1. revise cluster write stuff.
2. revise vn.c.
----- kgdb log ----
#0 boot (howto=260) at ../../kern/kern_shutdown.c:266
266 dumppcb.pcb_cr3 = rcr3();
(kgdb) bt
#0 boot (howto=260) at ../../kern/kern_shutdown.c:266
#1 0xf010162e in db_fncall (dummy1=-272631644, dummy2=0, dummy3=-266585388,
dummy4=0xefbff860 "\n") at ../../ddb/db_command.c:539
#2 0xf0101365 in db_command (last_cmdp=0xf01bbb24, cmd_table=0xf01bb974,
aux_cmd_tablep=0xf01cd0f8) at ../../ddb/db_command.c:337
#3 0xf01014e2 in db_command_loop () at ../../ddb/db_command.c:462
#4 0xf0103c28 in db_trap (type=3, code=0) at ../../ddb/db_trap.c:73
#5 0xf019ccbb in kdb_trap (type=3, code=0, regs=0xefbff950)
at ../../i386/i386/db_interface.c:126
#6 0xf01a6164 in trap (frame={tf_es = 16, tf_ds = 16, tf_edi = -262329344,
tf_esi = -266824827, tf_ebp = -272631404, tf_isp = -272631432,
tf_ebx = 256, tf_edx = -266744191, tf_ecx = 1017, tf_eax = 18,
tf_trapno = 3, tf_err = 0, tf_eip = -266744135, tf_cs = -272695288,
tf_eflags = 582, tf_esp = -266744207, tf_ss = -267318696})
at ../../i386/i386/trap.c:403
#7 0xf019ceb9 in Debugger (msg=0xf0110a58 "panic")
at ../../i386/i386/db_interface.c:254
#8 0xf0110aba in panic (
fmt=0xf0189385 "ufs_lock: recursive lock not expected, pid: %d\n")
at ../../kern/kern_shutdown.c:388
#9 0xf018941e in ufs_lock (ap=0xefbffa24) at ../../ufs/ufs/ufs_vnops.c:1715
#10 0xf010463e in vnstrategy (bp=0xf250c2e8) at vnode_if.h:731
#11 0xf0134e5e in spec_strategy (ap=0xefbffab0)
at ../../miscfs/specfs/spec_vnops.c:511
#12 0xf01895ea in ufs_strategy (ap=0xefbffab0)
at ../../ufs/ufs/ufs_vnops.c:1839
#13 0xf01274f0 in bwrite (bp=0xf250c2e8) at vnode_if.h:1116
#14 0xf01275ba in vn_bwrite (ap=0xefbffaec) at ../../kern/vfs_bio.c:386
#15 0xf0127f8c in vfs_bio_awrite (bp=0xf250c2e8) at vnode_if.h:1133
#16 0xf01281a0 in getnewbuf (slpflag=0, slptimeo=0, size=4096, maxsize=4096)
at ../../kern/vfs_bio.c:924
#17 0xf01286d5 in getblk (vp=0xf05a7180, blkno=219, size=4096, slpflag=0,
slptimeo=0) at ../../kern/vfs_bio.c:1197
#18 0xf0180479 in ffs_balloc (ip=0xf0597200, bn=219, size=4096,
cred=0xf05a1e80, bpp=0xefbffc90, flags=0) at ../../ufs/ffs/ffs_balloc.c:286
#19 0xf018338d in ffs_write (ap=0xefbffce4)
at ../../ufs/ufs/ufs_readwrite.c:260
#20 0xf01046a4 in vnstrategy (bp=0xf24e40f4) at vnode_if.h:283
#21 0xf0134e5e in spec_strategy (ap=0xefbffd84)
at ../../miscfs/specfs/spec_vnops.c:511
#22 0xf01895ea in ufs_strategy (ap=0xefbffd84)
at ../../ufs/ufs/ufs_vnops.c:1839
#23 0xf01274f0 in bwrite (bp=0xf24e40f4) at vnode_if.h:1116
#24 0xf01275ba in vn_bwrite (ap=0xefbffda4) at ../../kern/vfs_bio.c:386
#25 0xf01276c8 in bawrite (bp=0xf24e40f4) at vnode_if.h:1133
#26 0xf012af17 in cluster_wbuild (vp=0xf059bb00, size=4096, start_lbn=188,
len=16) at ../../kern/vfs_cluster.c:705
#27 0xf012ab21 in cluster_write (bp=0xf250e0fc, filesize=770048)
at ../../kern/vfs_cluster.c:555
#28 0xf0183584 in ffs_write (ap=0xefbffee8)
at ../../ufs/ufs/ufs_readwrite.c:291
#29 0xf0131597 in vn_write (fp=0xf05da400, uio=0xefbfff34, cred=0xf058ad80)
at vnode_if.h:283
#30 0xf0117c83 in write (p=0xf04f9a00, uap=0xefbfff94, retval=0xefbfff84)
at ../../kern/sys_generic.c:263
#31 0xf01a6ba7 in syscall (frame={tf_es = 39, tf_ds = -272695257,
tf_edi = 73728, tf_esi = 4, tf_ebp = -272640220, tf_isp = -272629788,
tf_ebx = 0, tf_edx = 512, tf_ecx = 0, tf_eax = 4, tf_trapno = 0,
tf_err = 7, tf_eip = 134708913, tf_cs = 31, tf_eflags = 582,
tf_esp = -272640244, tf_ss = 39}) at ../../i386/i386/trap.c:890
#32 0x8077eb1 in ?? ()
#33 0x9741 in ?? ()
#34 0x9c29 in ?? ()
#35 0x4c2c in ?? ()
#36 0x7b89 in ?? ()
#37 0x1095 in ?? ()
----- end -----
----
KATO Takenori <kato@ganko.eps.nagoya-u.ac.jp>
Dept. Earth Planet. Sci., Nagoya Univ., Nagoya, 464-01, Japan
PGP public key: finger kato@eclogite.eps.nagoya-u.ac.jp
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