>Number:         25595
>Category:       kern
>Synopsis:       pagefault fails to release kernel_lock when going to block
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun May 16 12:52:00 UTC 2004
>Closed-Date:
>Last-Modified:
>Originator:     YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>
>Release:        NetBSD 2.0E
>Organization:

>Environment:
	
	
System: NetBSD kaeru 2.0E NetBSD 2.0E (build.kaeru) #1299: Sun May 16 19:28:27 JST 2004 takashi@kaeru:/home/takashi/work/kernel/build.kaeru i386
Architecture: i386
Machine: i386
>Description:
	(the following example assumes i386.
	but i don't think that other ports are very different.)
	1. syscall() uses copyin() for syscall args without
	   holding kernel_lock.
	2. trap() uses KERNEL_LOCK to grab kernel_lock.
	3. uvm_fault blocks.
	4. as L_BIGLOCK isn't set, kernel_lock won't be released in mi_switch.
>How-To-Repeat:
>Fix:
	change KERNEL_PROC_LOCK to use LK_CANRECURSE and use it for traps?
	probably it's better to unify KERNEL_LOCK and KERNEL_PROC_LOCK.
>Release-Note:
>Audit-Trail:
>Unformatted: