Patch Name: PHKL_28120

Patch Description: s700_800 11.22 Lowfat/Hyperfabric data corruption

Creation Date: 02/10/28

Post Date:  02/10/30

Hardware Platforms - OS Releases:
	s700: 11.22
	s800: 11.22

Products: N/A

Filesets:
	OS-Core.CORE2-KRN,fr=B.11.22,fa=HP-UX_B.11.22_IA,v=HP

Automatic Reboot?: Yes

Status: General Release

Critical:
	Yes
	PHKL_28120: CORRUPTION HANG
		MPI/Lowfat applications hang as they receive
		corrupt data.

Category Tags:
	defect_repair general_release critical halts_system
	corruption

Path Name: /hp-ux_patches/s700_800/11.X/PHKL_28120

Symptoms:
	PHKL_28120:
	( SR:8606278367 CR:JAGae42425 )
	Applications using the Message Passing Interface (MPI)
	hang after some time as they receive corrupt data. This
	problem can be seen on systems running MPI or lowfat
	applications with hyperfabric cards.

	Note for application developers:
	When the parent forks and the child exits before the
	parent (MPI/Lowfat application) sends or receives data,
	there could be data corruption. The behavior is evident
	when using a popen() or pclose() call and immediately
	starting data transfer via lowfat.

Defect Description:
	PHKL_28120:
	( SR:8606278367 CR:JAGae42425 )
	When MPI or Lowfat applications fork a child process and
	make the child exit, the child, which shares the parents
	data pages (because of the Copy On Write feature of
	fork), incorrectly clears a bit in the shared pages used
	to trigger a callback from lowfat during the copy
	operation.  This callback is needed to inform the parent
	of its new page address.  Without this, the parent
	continues to hold the address of the old shared page.
	This action leads to data corruption for the parent.
	This defect exists in the super pages  ( > 4K) code only.

	Resolution:
	When a parent forks multiple children and one child
	exits, the child should not be allowed to write to
	the shared pages if the Copy On Write bit is set.

Enhancement:
	No

SR:
	8606278367

Patch Files:
	
	OS-Core.CORE2-KRN,fr=B.11.22,fa=HP-UX_B.11.22_IA,v=HP:
	/usr/conf/lib/libvm.a(vm_pregion.o)

what(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.22,fa=HP-UX_B.11.22_IA,v=HP:
	/usr/conf/lib/libvm.a(vm_pregion.o):
		vm_pregion.c $Date: 2002/09/27 14:19:37 $Revision: r
			11.22/1 PATCH_11.22 (PHKL_28120)

cksum(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.22,fa=HP-UX_B.11.22_IA,v=HP:
	413283888 69192 /usr/conf/lib/libvm.a(vm_pregion.o)

Patch Conflicts: None

Patch Dependencies: None

Hardware Dependencies: None

Other Dependencies: None

Supersedes: None

Equivalent Patches: None

Patch Package Size: 90 KBytes

Installation Instructions:
	Please review all instructions and the Hewlett-Packard
	SupportLine User Guide or your Hewlett-Packard support terms
	and conditions for precautions, scope of license,
	restrictions, and, limitation of liability and warranties,
	before installing this patch.
	------------------------------------------------------------
	1. Back up your system before installing a patch.

	2. Login as root.

	3. Copy the patch to the /tmp directory.

	4. Move to the /tmp directory and unshar the patch:

		cd /tmp
		sh PHKL_28120

	5. Run swinstall to install the patch:

		swinstall -x autoreboot=true -x patch_match_target=true \
			  -s /tmp/PHKL_28120.depot

	By default swinstall will archive the original software in 
	/var/adm/sw/save/PHKL_28120.  If you do not wish to retain a
	copy of the original software, include the patch_save_files
	option in the swinstall command above:

		-x patch_save_files=false

	WARNING: If patch_save_files is false when a patch is installed,
		 the patch cannot be deinstalled.  Please be careful
		 when using this feature.

	For future reference, the contents of the PHKL_28120.text file is 
	available in the product readme:

		swlist -l product -a readme -d @ /tmp/PHKL_28120.depot

	To put this patch on a magnetic tape and install from the
	tape drive, use the command:

		dd if=/tmp/PHKL_28120.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions: None