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Patch Name: PHKL_27091
Patch Description: s700_800 11.11 Core PM, vPar, Psets Cumulative, slpq1 perf
Creation Date: 02/06/05
Post Date: 02/10/02
Repost: 02/12/05
The patch documentation was modified to add information on
an additional issue addressed by the patch. PHKL_27091
addresses the run queue corruption problem described in
SR 8606236276 (JAGae05337). Information on this additional
issue was added to the Symptoms, Defect Description, and
SR fields.
Hardware Platforms - OS Releases:
s700: 11.11
s800: 11.11
Products: N/A
Filesets:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP
Automatic Reboot?: Yes
Status: General Superseded
Critical:
Yes
PHKL_27091: PANIC HANG
PHKL_24257: OTHER
Hung, Unkillable Process
Category Tags:
defect_repair enhancement general_release critical panic
halts_system manual_dependencies
Path Name: /hp-ux_patches/s700_800/11.X/PHKL_27091
Symptoms:
PHKL_27091:
( SR:8606249635 CR:JAGae16022 )
Applications may hang with threads in the accept(2) system
call. The problem occurs only when multiple threads are
issuing accept(2) on the same socket, and when no thread
calls accept(2) again after a thread is interrupted by a
signal.
( SR:8606259436 CR:JAGae23754 )
System may panic with data page fault in clock interrupt
path. The stack trace is as follows:
panic+0x14
report_trap_or_int_and_panic+0x84
interrupt+0x1d4
$ihndlr_rtn+0x0
determine_processor_state+0xbc
per_spu_hardclock+0xc8
clock_int+0x58
mp_ext_interrupt+0x150
ivti_patch_to_nop3+0x0
idle+0x108
swidle_exit+0x0
( SR:8606234249 CR:JAGae03469 )
Enhancement: This product update is a member of a set
needed to support the kernel sleep/wakeup queuing
performance enhancement. The full list of product updates
required for this feature are: PHKL_27091, PHKL_27294,
PHKL_27093 and PHKL_27094.
Performance degradation may be seen on systems in
which a large number (500 or more) of TIMESHARE threads
call the accept(2) function on a single socket.
( SR:8606245859 CR:JAGae12318 )
Processes which call vfork(2) can sometimes hang and
become unkillable. Further, executing a setpriority(2)
operation (e.g. via renice(1M)) on such a process may
cause a kernel panic due to a Data Page Fault, with the
stack trace:
is_realtime+0x0
get_pregionnice+0x34
update_preg_nice+0x44
donice+0xc8
setpriority+0x6c
syscall+0x750
syscallinit+0x5b0
( SR: 8606236276 CR:JAGae05337 )
Panics due to run queue corruption may occur on systems
with patches PHKL_24551 or PHKL_25389. The panics occur
on systems in which at least one processor is idle, and
symptoms may take the form of a data page fault panic
in find_thread_other_spu() or gs_rendezvous_thread(),
or a spinlock deadlock panic on the 'Per SPU RUNQ Lock'.
PHKL_25389:
( SR:8606215976 CR:JAGad85148 )
When thousands of threads are waiting on a select(2) call,
application performance slows down considerably. This is
an enhancement to sleep queues to boost performance.
( SR:8606226427 CR:JAGad95496 )
Possible races from kernel subsystems that assume the
entry to kernel sleep is atomic. This can result in
missed wakeup events.
PHKL_24551:
( SR:8606200799 CR:JAGad69975 )
This patch is a member of a set of patches needed to enable
the HP-UX Processor Sets product (PROCSETS). When PROCSETS
product is installed, it will install the full set of
required patches for that product, including this patch.
If the HP-UX Processor Sets product is not installed, this
change will have no Processor Sets impact on your system.
( SR:8606199577 CR:JAGad68764 )
This patch is a member of a set of patches needed to enable
the HP-UX Virtual Partitions product Sets. When the HP-UX
Virtual Partitions product (VPARSBASE or T1335AA) is
installed, it will install the full set of required patches
for that product, including this patch.
If the HP-UX Virtual Partitions product is not installed,
this change will have no Virtual Partitions impact on your
system.
( SR:8606194817 CR:JAGad64023 )
Load averages reported by such utilities as top and uptime
are overall higher in 11.11 than they were in earlier
releases.
PHKL_23665:
( SR:8606128017 CR:JAGac78818 )
vhand priority does not match scheduling policy for brief
durations.
PHKL_24257:
( SR:8606159451 CR:JAGad28779 ) Duplicate
( SR:8606103740 CR:JAGab70789 )
A multi-threaded process being executed over NFS can become
hung and unkillable while performing either a fork, core,
setrlimit, SIGSTOP, or debugger operations. This can happen
with mutiple threads in different processes competing for
the same resource when one thread is stopped.
Defect Description:
PHKL_27091:
( SR:8606249635 CR:JAGae16022 )
A thread receiving an event wakeup and a signal
simultaneously will handle the signal. The event will not
be handled even though there may be other threads
waiting for that event. They will wait forever, unless
another duplicate event occurs.
Resolution:
A signaled thread will now determine if it also received
an event wakeup. If so, it will wake up the next waiting
thread to handle the event.
( SR:8606259436 CR:JAGae23754 )
A clock interrupt occuring as soon as the idle loop
enables interrupts may attempt to dereference a null
thread pointer if the cpu state is stale, causing the
panic.
Resolution:
Set the processor state information earlier in the idle
loop, before interrupts are enabled.
( SR:8606234249 CR:JAGae03469 )
This product update contains a performance enhancement to
the kernel sleep/wakeup queuing mechanism.
Resolution:
Implement a new sleep/wakeup queuing mechanism that
addresses the performance issue.
( SR:8606245859 CR:JAGae12318 )
A race condition in vfork(2) causes a wakeup to be missed.
As the parent is left in an incoherent state, a subsequent
priority setting operation encounters a stale pointer,
causing the Data Page Fault.
Resolution:
Fixed operation sequence to close the race, so that the
wakeup is not missed.
( SR: 8606236276 CR:JAGae05337 )
Patches PHKL_24551 and PHKL_25389 introduced a race
condition in the interaction between the idle and suspend
paths, leading to a thread being in an inconsistent state
while either actively running or on the run queue.
Resolution:
In PHKL_27091 the race condition no longer exists.
PHKL_25389:
( SR:8606215976 CR:JAGad85148 )
This is an enhancement for a performance problem seen while
trying to remove a single thread from a long sleep queue.
This would be useful to customers who are making numerous
system calls that would cause threads to sleep on the same
sleep queue, such as select(2).
Resolution:
The sleep queues were changed from a single-linked list to
a double-linked list.
( SR:8606226427 CR:JAGad95496 )
This is an enhancment that allows kernel subsystems to
enter kernel sleep with alternative locking rules. By
permitting these new locking rules, other subsystems are
able to close race windows around entering and leaving
kernel sleep. If there is no other patch that requires
this change, it will do nothing.
Resolution:
Permit kernel subsystems entering kernel sleep to hold
an additional resource to prevent race conditions .
PHKL_24551:
( SR:8606200799 CR:JAGad69975 )
This patch contains minor enhancements required to support
the HP-UX Processor Sets product.
Resolution:
Enhancements added to enable scheduler to recognize and
work with processor sets when the Processor Sets product
is enabled.
( SR:8606199577 CR:JAGad68764 )
This patch contains minor enhancements required to support
the HP-UX Virtual Partitions product.
Resolution:
Enhancements added to support CPU migration.
( SR:8606194817 CR:JAGad64023 )
System daemon threads are factored into the load average
calculations in 11.11 where they were not in earlier
releases. This makes the reported load averages higher
than they were in earlier releases.
Resolution:
This patch changes the load average calculations to once
more disregard system daemon threads, resulting in load
averages much more closely aligned to those in earlier
releases.
PHKL_23665:
( SR:8606128017 CR:JAGac78818 )
When vhand's priority is increased due to it being
preempted, there is a race with other threads which are
also raising vhand's priority at the same time. Thus,
when vhand switches back to run again, its policy and
priority number do not match. The priority and policy
will be back in sync once the thread which elevated the
priority of vhand is restored to run again.
Resolution:
Preemption_point no longer elevates the priority of the
preempted thread.
PHKL_24257:
( SR:8606159451 CR:JAGad28779 ) Duplicate
( SR:8606103740 CR:JAGab70789 )
A thread acquires a lock and then sleeps interruptibly. The
interruptible sleep permits the thread to be stopped. Any
other thread attempting to acquire this lock will sleep
uninterruptibly until the lock is available. This
uninterruptible thread is also unkillable. This introduces
a deadlock potential in multi-threaded processes: when a
thread holding the lock, a thread desiring the lock, and a
third thread doing one of fork, setrlimit, core, SIGSTOP, or
debugger operations, all occur at the same time in the
same process, the deadlock is reached. The only way to
resolve the deadlock is to reboot the system. A similar
situation can occur when threads in different processes
are competing for the same NFS resource and the thread that
owns that resource is stopped via a signal, a debugger,
or a ctrl-Z.
This patch is part of a set of five patches (PHKL_24253,
PHKL_24254,PHKL_24255,PHKL_24256,PHKL_24257) that enable
P_NOSTOP, a new feature that prevents a process from being
unkillable. Each patch is independently installable.
Without all five installed, P_NOSTOP will be unavailable.
In order to prevent the process executed over NFS from
becoming unkillable, NFS must use the P_NOSTOP feature.
Usage of this feature was added to PHNE_23502.
Resolution:
If a thread acquires a lock and then sleeps interruptibly,
it is not permitted to be stopped if P_NOSTOP is set. This
prevents this thread from becoming unkillable and prevents
the deadlock.
SR:
8606103740 8606128017 8606159451 8606194817 8606226427
8606199577 8606200799 8606215976 8606234249 8606245859
8606249635 8606259436 8606236276
Patch Files:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
/usr/conf/lib/libpm.a(pm_swtch.o)
/usr/conf/lib/libvm.a(vm_stats.o)
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
/usr/conf/lib/libpm.a(pm_swtch.o)
/usr/conf/lib/libvm.a(vm_stats.o)
what(1) Output:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
/usr/conf/lib/libpm.a(pm_swtch.o):
pm_swtch.c $Date: 2002/05/16 11:07:30 $Revision: r11
.11/9 PATCH_11.11 (PHKL_27091)
/usr/conf/lib/libvm.a(vm_stats.o):
vm_stats.c $Date: 2001/07/17 16:02:01 $Revision: r11
.11/1 PATCH_11.11 (PHKL_24551)
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
/usr/conf/lib/libpm.a(pm_swtch.o):
pm_swtch.c $Date: 2002/05/16 11:07:30 $Revision: r11
.11/9 PATCH_11.11 (PHKL_27091)
/usr/conf/lib/libvm.a(vm_stats.o):
vm_stats.c $Date: 2001/07/17 16:02:01 $Revision: r11
.11/1 PATCH_11.11 (PHKL_24551)
cksum(1) Output:
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_32,v=HP:
3708886638 48884 /usr/conf/lib/libpm.a(pm_swtch.o)
851993213 10060 /usr/conf/lib/libvm.a(vm_stats.o)
OS-Core.CORE2-KRN,fr=B.11.11,fa=HP-UX_B.11.11_64,v=HP:
2403824547 109712 /usr/conf/lib/libpm.a(pm_swtch.o)
371782419 24672 /usr/conf/lib/libvm.a(vm_stats.o)
Patch Conflicts: None
Patch Dependencies:
s700: 11.11: PHKL_27294 PHKL_27093 PHKL_27094
s800: 11.11: PHKL_27294 PHKL_27093 PHKL_27094
Hardware Dependencies: None
Other Dependencies:
PHKL_24257: If NFS is installed on the system, all five
patches (PHNE_23502, PHKL_24253, PHKL_24254,PHKL_24255,
PHKL_24256, PHKL_24257) are required to resolve the process
hang/deadlock due to unkillable processes executed over NFS.
However, if NFS is not in use, none of these patches are
required.
Supersedes:
PHKL_25389 PHKL_24551 PHKL_24257 PHKL_23665
Equivalent Patches: None
Patch Package Size: 230 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_27091
5. Run swinstall to install the patch:
swinstall -x autoreboot=true -x patch_match_target=true \
-s /tmp/PHKL_27091.depot
By default swinstall will archive the original software in
/var/adm/sw/save/PHKL_27091. 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_27091.text file is
available in the product readme:
swlist -l product -a readme -d @ /tmp/PHKL_27091.depot
To put this patch on a magnetic tape and install from the
tape drive, use the command:
dd if=/tmp/PHKL_27091.depot of=/dev/rmt/0m bs=2k
Special Installation Instructions: None
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