>Number:         2240
>Category:       kern
>Synopsis:       I/O error from disk crash nfs servers
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people (Kernel Bug People)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Mar 18 17:20:06 1996
>Last-Modified:
>Originator:     Manuel Bouyer
>Organization:
Ecole Nationale Superieure de Techniques Avancees, Paris
>Release:        NetBSD-current, sup from 04 march 1996
>Environment:
System: NetBSD chassiron.ensta.fr 1.1A NetBSD 1.1A (CHASSIRON) #4: Tue Mar 5 20:20:31 MET 1996 bouyer@:/usr/src/src_current/sys/arch/i386/compile/CHASSIRON i386


>Description:
	I've a CD-ROM with unreadable blocks. When trying to access a file
	with one of these blocks locally, the drive return a "Medium error",
	and the reading process get a I/O error.
	But if this CD-ROM is nfs-mounted, when the client tries to access this
	file, I get the "Medium error" on console, and just after the system crash
	with: "panic: free: multiple frees".
	Here is the trace :
	_Debugger
	_Panic
	_Free at _Free+0xfb
	_m_freem at _m_freem+0xc9
	_nfsrv_read at _nfsrv_read+0xfee
	_nfssvc_nfsd at _nfssvc_nfsd+0x4e8
	_sys_nfssvc at _sys_nfssvc+0x512
	_sycazll at _sycazll+0x224
	--- syscall (number 155) ---
	This is perfectly reproductible.

	I had a buggy disk on an nfs server, but I don't remember of such crash,
	so this could be a iso9660/nfs problem. However I don't have any drive
	with bad blocks to test it.

>How-To-Repeat:
	Find a CD-ROM with bad sectors, nfs_mount it, and read it.
>Fix:
	Unknow, if someone send me a path, i can try it.
>Audit-Trail:
>Unformatted: