Patch Name: PHKL_29851

Patch Description: s700_800 11.00 ufs(hfs) deadlock causes system hang

Creation Date: 03/10/06

Post Date: 03/10/17

Hardware Platforms - OS Releases:
	s700: 11.00
	s800: 11.00

Products: N/A

Filesets:
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP

Automatic Reboot?: Yes

Status: General Release

Critical:
	Yes
	PHKL_29851: HANG
	PHKL_22932: HANG

Category Tags:
	defect_repair general_release critical halts_system

Path Name: /hp-ux_patches/s700_800/11.X/PHKL_29851

Symptoms:
	PHKL_29851:
	( SR:8606320306 CR:JAGae82790 )
	Two threads hang due to a deadlock between the two. The
	stacktraces of the hanging threads will look like the
	following.

	_swtch+0xd4
	_sleep+0x154
	blkflush+0x3ac
	ufspgin_blkflsh+0x70
	ufs_pagein+0x3dc
	virtual_fault+0x378
	vfault+0x118
	trap+0x284
	thandler+0xd20

	_swtch+0xd4
	 _sleep_one+0x170
	cilock_sleep+0x148
	ieget+0x400
	in_get+0x30
	iget+0x18
	dircheckforname+0x274
	dircheckwithsdo+0x58
	dirremove+0xbc
	ufs_remove+0x34
	vns_remove+0xa4
	vn_remove+0xa4
	unlink+0x28
	syscall+0x394
	syscallinit+0x54c

	PHKL_22932:
	(SR:8606160762 CR:JAGad30082)
	A deadlock occurs while mmaping part of a file into a
	buffer, and when that buffer is used to do a read or
	write call to the very same file.
	If the file is opened with file descriptor "fd", and
	the same file is memory mapped to the region starting
	at address "addr", I/O to that file done with system
	call write/read will cause the system to hang.
	The problem occurs with UFS and some versions of
	netscape mail server.

	The thread will deadlock itself with the stack trace:

	ilock_reader+0x170
	ufs_lock_inode+0x14
	ufs_pagein+0x60
	virtual_fault+0x378
	vfault+0x118
	trap+0x590
	nokgdb+0x8
	copyin+0x104
	uiomove+0xc0
	rwip+0x380
	ufs_rdwr+0xe0
	vno_rw+0x80
	write+0x104
	syscall+0x480

Defect Description:
	PHKL_29851:
	( SR:8606320306 CR:JAGae82790 )
	This is a two-way deadlock. The first thread has acquired
	an inode lock and is waiting for a buffer lock. The second
	thread has acquired the buffer lock and is waiting for the
	inode lock to become free.
	This happens as the pagein routine tries to flush buffers
	for a 4k page from the buffer cache for a file. However
	the file size might not be 4k aligned. This could result
	in the attempt of flushing buffers belonging to a different
	file or directory.

	Resolution:
	The pagein routine was modified not to flush those blocks
	from the buffer cache which did not belong to the file
	which is being paged in.

	PHKL_22932:
	(SR:8606160762 CR:JAGad30082)
	A deadlock occurs because write to a rwip requires an
	inode lock in ilock() and later uiomove (copying from
	the user buffer to the buffer cache) can trigger a
	vfault which requires a read lock on the same inode.
	The deadlock occurs on the inode between read/write
	and ufs_pagein() when a page fault occurs on a mmaped
	buffer during the uiomove called by the read/write
	system call.

	Resolution:
	In ufs_pagein(), if the inode lock is already owned by
	the current thread, it is not locked again. This is the
	only path were a inode lock is tried to be locked twice,
	first in write mode then in reade mode. Ignoring the
	second locking is good enough to avoid the deadlock and
	does not break any protection.

Enhancement:
	No

SR:
	8606160762 8606320306

Patch Files:
	
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP:
	/usr/conf/lib/libhp-ux.a(ufs_vm.o)

	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP:
	/usr/conf/lib/libhp-ux.a(ufs_vm.o)

what(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP:
	/usr/conf/lib/libhp-ux.a(ufs_vm.o):
		ufs_vm.c $Date: 2003/10/03 06:52:35 $Revision: r11ro
			s/4 PATCH_11.00 (PHKL_29851)

	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP:
	/usr/conf/lib/libhp-ux.a(ufs_vm.o):
		ufs_vm.c $Date: 2003/10/03 06:52:35 $Revision: r11ro
			s/4 PATCH_11.00 (PHKL_29851)

cksum(1) Output:
	
	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_32,v=HP:
	3275950579 13896 /usr/conf/lib/libhp-ux.a(ufs_vm.o)

	OS-Core.CORE2-KRN,fr=B.11.00,fa=HP-UX_B.11.00_64,v=HP:
	880946365 24024 /usr/conf/lib/libhp-ux.a(ufs_vm.o)

Patch Conflicts: None

Patch Dependencies: None

Hardware Dependencies: None

Other Dependencies: None

Supersedes:
	PHKL_22932 

Equivalent Patches: None

Patch Package Size: 40 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_29851

	5. Run swinstall to install the patch:

		swinstall -x autoreboot=true -x patch_match_target=true \
			  -s /tmp/PHKL_29851.depot

	By default swinstall will archive the original software in 
	/var/adm/sw/save/PHKL_29851.  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_29851.text file is 
	available in the product readme:

		swlist -l product -a readme -d @ /tmp/PHKL_29851.depot

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

		dd if=/tmp/PHKL_29851.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions: None