Issue #2276 has been updated by Venkatesh Srinivas.
Here's the problem: MFS's mfs_start() routine is not like other filesystems; the userland mount_mfs enters the mfs_start routine and processes copyin/copyout requests to transfer data into its userland mmap-ed region. When it returns after either being signalled or the filesystem being unmounted, the mount structure is not valid. Unfortunately, sys_unmount() already kfree-d the mount structure; both the accounting init and MPUNLOCK(mp) in vfs_vfsops.c:vfs_start() are not safe; they are accessing the mountpoint after it is freed. ---------------------------------------- Bug #2276: umount mfs crash - Fatal trap 12 http://bugs.dragonflybsd.org/issues/2276 Author: Thomas Nikolajsen Status: New Priority: Normal Assignee: Category: Target version: Using fresh master (January 17th 2012), umount of mfs mount crashes system. This happens every time; core dump avail on request. -thomas - Fatal trap 12: page fault while in kernel mode .. > trace vfs_start() sys_mount() -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://bugs.dragonflybsd.org/my/account
