On Friday, July 09, 2010 10:27:46 pm Boris Kochergin wrote: > Hans Petter Selasky wrote: > > On Friday 09 July 2010 19:12:59 Sean Bruno wrote: > > > >> In order to come up with the most convoluted problem possible, I present > >> to you screen shots of a panic from a FreeBSD VM running in QEMU > >> emulation under RedHat's KVM infrastructure. > >> > >> I presented a perfectly functional USB partition from my host machine to > >> the VM. Then I attempted to mount the partition from FreeBSD and it > >> generated the panics located here: > >> > >> http://people.freebsd.org/~sbruno/usb_panic1.png > >> http://people.freebsd.org/~sbruno/usb_panic2.png > >> > >> This is 100% reproducible. But not an emergency or anything. > >> > > > > It might be that there is a conflict that both the VM and the OS is > > accessing > > / loading drivers on the same USB device. The panic seems not directly > > related > > to USB. > > > > --HPS > > > > > I followed the code for a while and the cause of the panic appears to be > that ffs_vgetf() in /usr/src/sys/ufs/ffs/ffs_vfsops.c fails in one of > the several ways possible, causing in VFS_ROOT() in > /usr/src/sys/kern/vfs_mount.c to return a non-zero value and resulting > in the panic. I think the problem calls for someone with serious VFS chops. > > The I/O errors from the USB device are suspicious (in that they may > cause the mount code to misbehave if they occur during its course).
Much of the filesystem code doesn't really handle I/O errors very gracefully. I do think trasz@ did some work a year or so ago to improve this somewhat. -- John Baldwin _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
