Date: Fri, 08 Jun 2012 22:01:26 +0200 From: Stefan Esser <se@freebsd.org> To: freebsd-current@freebsd.org Subject: Re: lock order reversal in sys/kern/vfs_mount.c Message-ID: <4FD25A16.9060509@freebsd.org> In-Reply-To: <4FD1B365.2010209@yandex.ru> References: <4FD1B365.2010209@yandex.ru>
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Am 08.06.2012 10:10, schrieb Ruslan Mahmatkhanov: > Good day, > > After updating to yesterdays -current, I got this on boot: > > lock order reversal: > 1st 0xfffffe0007b04c38 ufs (ufs) @ /usr/src/sys/kern/vfs_mount.c:1254 > 2nd 0xfffffe0007ed9478 devfs (devfs) @ /usr/src/sys/kern/vfs_subr.c:2158 > KDB: stack backtrace: > db_trace_self_wrapper() at db_trace_self_wrapper+0x2a > kdb_backtrace() at kdb_backtrace+0x37 > _witness_debugger() at _witness_debugger+0x2c > witness_checkorder() at witness_checkorder+0x853 > __lockmgr_args() at __lockmgr_args+0x113a > vop_stdlock() at vop_stdlock+0x39 > VOP_LOCK1_APV() at VOP_LOCK1_APV+0xbf > _vn_lock() at _vn_lock+0x47 > vget() at vget+0x7b > devfs_allocv() at devfs_allocv+0x13f > devfs_root() at devfs_root+0x4d > dounmount() at dounmount+0x45c > vfs_unmountall() at vfs_unmountall+0x4c > kern_reboot() at kern_reboot+0x84b > sys_reboot() at sys_reboot+0x68 > amd64_syscall() at amd64_syscall+0x2e0 > Xfast_syscall() at Xfast_syscall+0xf7 > --- syscall (55, FreeBSD ELF64, sys_reboot), rip = 0x40ebbc, rsp = > 0x7fffffffd6c8, rbp = 0x65 --- > > Reverting to old kernel (that was built about a week ago) helped to > avoid this. Any thoughts? I have been getting those for a long time in -CURRENT, but with ZFS instead of UFS, and during system shutdown, not startup. And this LOR seems to cause the system to lock-up on shutdown with relatively high probability (I often have to remove power to halt the system, Since the ACPI power-off is not issued because of the LOR). My system is only rebooted from the local console and thus the LOR is not that much of a problem, and I did not bother to further look into the cause. But in case of remote system that is rebooted via SSH, the LOR could be quite a nuisance ... Regards, STefan
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