2010/2/8 Kostik Belousov <kostikbel_at_gmail.com>: > On Mon, Feb 08, 2010 at 09:00:44AM -0500, John Baldwin wrote: >> On Sunday 07 February 2010 11:00:32 am Bruce Cran wrote: >> > Running -CURRENT from today, I unmounted the msdosfs filesystem on my >> > phone and got the following LOR: >> > >> > lock order reversal: >> > 1st 0xffffff00c51279f8 ufs (ufs) _at_ /usr/src/sys/kern/vfs_mount.c:1204 >> > 2nd 0xffffff010b892278 devfs (devfs) _at_ >> > /usr/src/sys/modules/msdosfs/../../fs/msdosfs/msdosfs_vfsops.c:944 >> > KDB: stack backtrace: >> > db_trace_self_wrapper() at db_trace_self_wrapper+0x2a >> > _witness_debugger() at witness_debugger+0x2e >> > witness_checkorder() at witness_checkorder+0x81e >> > __lockmgr_args() at __lockmgr_args+0xd11 >> > vop_stdlock() at vop_stdlock+0x39 >> > VOP_LOCK1_APV() VOP_LOCK1_APV+0x9b >> > _vn_lock() at _vn_lock+0x47 >> > msdosfs_sync() at msdosfs_sync+0x227 >> > dounmount() at dounmount+0x2ca >> > unmount() at unmount+0x216 >> > syscall() at syscall+0x2a2 >> > Xfast_syscall() at Xfast_syscall+0xe1 >> > --- syscall (22, FreeBSD ELF64, unmount), rip = 0x8006a1e3c, rsp = >> > 0x7fffffffe3a8, rbp = 0x800c08010 --- >> >> This is due to holding a lock on the coveredvp vnode for most of unmount(2). >> Probably it should not be held for all of that. Perhaps it is safe to just >> keep the vnode referenced instead, or could the handling for coveredvp just >> move to the end of the function where it is now vput? > > Among other things, holding vnode lock on covered vnode prevents parallel > unmounts of the same mount point. Uhm, I think that this should be hanlded by MNTK_UNMOUNT already (and thus stopping forced unmounts too). Attilio -- Peace can only be achieved by understanding - A. EinsteinReceived on Mon Feb 08 2010 - 14:01:59 UTC
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