Bug #418560 “Unfinished shutdown or reboot” : Bugs : linux package : Ubuntu

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Nils Kassube (kassube) wrote on 2009-08-25:

#1

dmesg.txt Edit (40.7 KiB, text/plain)

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Nils Kassube (kassube) wrote on 2009-08-25:

#2

lspci-vvnn.txt Edit (16.8 KiB, text/plain)

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Nils Kassube (kassube) wrote on 2009-08-25:

#3

version.txt Edit (27 bytes, text/plain)

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Nils Kassube (kassube) wrote on 2009-08-25:

#4

uname-a.txt Edit (91 bytes, text/plain)

Collin (collin-schroeder) on 2009-08-26

Changed in linux (Ubuntu):
status:	New → Confirmed

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Yvan (yvan-tardy) wrote on 2009-08-26:

#5

Same problem on a Thinkpad T60

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Ronnie (ronnie.vd.c) wrote on 2009-08-26:

#6

Same problem here

HP 6530b
64 bit
Ubuntu (Gnome)
Kernel 2.6.31-7

last line: Checking for running unattended-upgrades: * Asking all remaining processes to terminate...

Revision history for this message

starslights (starslights) wrote on 2009-08-26:

#7

same problem on kubuntu karmic alpha4 x86 64

ame message and never shutdown or reboot, need cuting the power...

Stefano Maioli (smaioli) on 2009-08-26

tags:

added: regression-potential

Noel J. Bergman (noeljb) on 2009-08-27

tags:

added: karmic

Revision history for this message

Jan Kaessens (jck) wrote on 2009-08-27:

#9

Same here, on 2.6.31-7-generic-pae i686.

Excerpt from daemon.log:
Aug 27 00:35:30 janni avahi-daemon[3801]: Withdrawing address record for 10.23.0.2 on tap0.
Aug 27 00:35:31 janni init: rc main process (11426) stopped by STOP signal
<-- Right here stdout says "Checking for running unattended-upgrades:" during shutdown -->
Aug 27 00:35:31 janni init: rc main process (11426) continued by CONT signal
Aug 27 00:35:31 janni acpid: exiting
Aug 27 00:35:31 janni avahi-daemon[3801]: Disconnected from D-Bus, exiting.
Aug 27 00:35:31 janni avahi-daemon[3801]: Got SIGTERM, quitting.
Aug 27 00:35:31 janni avahi-daemon[3801]: write() failed: Broken pipe
Aug 27 00:35:31 janni avahi-daemon[3801]: Leaving mDNS multicast group on interface eth0.IPv4 with address 10.0.0.2.
Aug 27 00:35:31 janni init: Disconnected from system bus
Aug 27 00:35:31 janni avahi-daemon[3801]: write() failed: Broken pipe
... and that's the last message.

According to /usr/share/unattended-upgrades/unattended-upgrades-shutdown it should say
"Giving up lockfile after xx delay" so perhaps it's about that "while True"-loop in there.

Revision history for this message

Jan Kaessens (jck) wrote on 2009-08-27:

#10

Okay, I changed the init script /etc/init.d/unattended-updates so that
/usr/share/unattended-upgrades/unattended-upgrade-shutdown is called with --debug:

Aug 27 12:11:20 janni GetLock returned 4
Aug 27 12:11:20 janni Lock not taken
Aug 27 12:12:59 janni GetLock returned 4
Aug 27 12:12:59 janni Lock not taken
Aug 27 12:14:03 janni GetLock returned 4
Aug 27 12:14:03 janni Lock not taken

in the above script it says (line 78 ff.):

        res = apt_pkg.GetLock(options.lock_file)
        logging.debug("GetLock returned %i" % res)
        if res > 0:
            logging.debug("Lock not taken")
            sys.exit(0)
        # "wait for 5s, try again or bail out with timeout error" stuff

apt_pkg.GetLock documentation says, that the lock is not taken when result == -1, otherwise the Fd of the lock is returned. I believe it should be "if res < 0" but I don't usually do python, apt-debugging and people say, this works
in 2.6.31-6.

HTH

Revision history for this message

Jan Kaessens (jck) wrote on 2009-08-27:

#11

Mmmh.. I think I understood. Please dismiss my last comment ;-)
"Lock not taken" means "The lock is free to be taken -> there's no process locking it" instead of "I couldn't get the lock"...

Revision history for this message

Peter W Bowey (support-pbcomp.com.au) wrote on 2009-08-27:

#12

Confirmed: Latest kernel 2.6.31-7 (not rc7) hangs on reboot or shutdown! No time-out occurs.
Any effort to force the shutdown (keys or commands) - other than physical 'System Power Off' fails.
This occurs even with DBUS disabled. No System logs exist to clarify further on this kernel event 'hang'.

Revision history for this message

Peter W Bowey (support-pbcomp.com.au) wrote on 2009-08-27:

#13

If one tries Control-Alt-Del on this Kernel 26.31.-7 shutdown / restart hang, the initial message is:

"Init: rc main process (6281) stopped by STOP signal"
"Init: rc main process (6281) continued by CONT signal"

Further attempts at 'Control-Alt-Del' show this message:

"The system is going down for a reboot NOW!"
"Control-Alt-Del pressed"

This repeats for further attempts at 'Control-Alt-Del'

Hard Poweroff is the only resort!

Revision history for this message

Jan Kaessens (jck) wrote on 2009-08-27:

#14

Confirming that shutdown works nicely on 2.6.31-6-generic-pae.
Don't know what these things mean but here's the changelog between 2.6.31-6 and 2.6.31-7

linux (2.6.31-7.27) karmic; urgency=low
  [ Tim Gardner ]
  * [Config] updateconfigs updateportsconfigs after 2.6.31-rc7 rebase
  * SAUCE: (drop after 2.6.31) Added KSM from mmotm-2009-08-20-19-18
    Replaces previous ksm patches from 2.6.31-6.25
  * [Config] KSM=y

-- Tim Gardner <email address hidden> Sat, 22 Aug 2009 20:32:11 -0600

HTH,
jan

Revision history for this message

kajhaul (kaj-haulrich) wrote on 2009-08-27: Re: [Bug 418560] Re: Unfinished shutdown or reboot

#15

On Thursday 27 August 2009 13:50:59 Peter W Bowey wrote:
> Confirmed: Latest kernel 2.6.31-7 (not rc7) hangs on reboot or
> shutdown! No time-out occurs. Any effort to force the shutdown
> (keys or commands) - other than physical 'System Power Off'
> fails. This occurs even with DBUS disabled. No System logs exist
> to clarify further on this kernel event 'hang'.

Actually, you can reboot the system with the keyboard in a safe way.
Use the 'Elephant' sequence:
In a sequential order, press <Alt>+<SysRq>+<r> - this will put the
keyboard in 'raw' mode. Then, continue the sequence by replacing the
<r> above with <s>, <e>, <i>, <u>, <b> - (wait a few seconds between
each three-finger combination).
(Memo: Raising Skinny Elephants Is Utterly Boring)
--
*** Sent from a 100% Microsoft-free computer ***
********* Running Linux Kubuntu 9.10 *********

Revision history for this message

Peter W Bowey (support-pbcomp.com.au) wrote on 2009-08-27:

#16

Diving into the kernel changes that occurred from linux-26.31-6.26x - dated 2009-08-21 (working) --to-- the new update on 2009-08-24 (not working) linux-2.6.31-7.27, I can only find internal kernel these changes:

1) = [ Taken from the linux_2.6.31-6.26_2.6.31-7.27.diff.gz#patchfs/linux-2.6.31/debian.master/config/config.common.ports.diff: ]

------------------------------------------------------------------------------------------------------------------------------------------------------------

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/debian.master/config/config.common.ports /tmp/Td2i4nRkP9/linux-2.6.31/debian.master/config/config.common.ports
--- linux-2.6.31/debian.master/config/config.common.ports 2009-08-21 18:39:57.000000000 +0100
+++ linux-2.6.31/debian.master/config/config.common.ports 2009-08-24 18:08:33.000000000 +0100
@@ -1622,6 +1622,7 @@
# CONFIG_LPARCFG is not set
# CONFIG_LP_CONSOLE is not set
CONFIG_LSI_ET1011C_PHY=m
+CONFIG_LSM_MMAP_MIN_ADDR=65536
CONFIG_LXT_PHY=m
CONFIG_M25PXX_USE_FAST_READ=y
CONFIG_MA600_DONGLE=m
------------------------------------------------------------------------------------------------------------------------------------------------------------

2) = [ and from the linux_2.6.31-6.26_2.6.31-7.27.diff.gz#patchfs/linux-2.6.31/debian.master/config/config.common.ubuntu.diff: ]

------------------------------------------------------------------------------------------------------------------------------------------------------------

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/debian.master/config/config.common.ubuntu /tmp/Td2i4nRkP9/linux-2.6.31/debian.master/config/config.common.ubuntu
--- linux-2.6.31/debian.master/config/config.common.ubuntu 2009-08-21 18:39:57.000000000 +0100
+++ linux-2.6.31/debian.master/config/config.common.ubuntu 2009-08-24 18:08:33.000000000 +0100
@@ -1930,6 +1930,7 @@
CONFIG_LP486E=m
# CONFIG_LP_CONSOLE is not set
CONFIG_LSI_ET1011C_PHY=m
+CONFIG_LSM_MMAP_MIN_ADDR=65536
CONFIG_LTPC=m
CONFIG_LXT_PHY=m
CONFIG_LZO_COMPRESS=m

------------------------------------------------------------------------------------------------------------------------------------------------------------

These are the only clues I can offer to the current kernel change!

Diving into the kernel changes that occurred from linux-26.31-6.26x - dated 2009-08-21 (working) --to-- the new update on 2009-08-24 (not working) linux-2.6.31-7.27, I can only find internal kernel these changes:

1) = [ Taken from the linux_2.6.31-6.26_2.6.31-7.27.diff.gz#patchfs/linux-2.6.31/debian.master/config/config.common.ports.diff: ]

------------------------------------------------------------------------------------------------------------------------------------------------------------

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/debian.master/config/config.common.ports /tmp/Td2i4nRkP9/linux-2.6.31/debian.master/config/config.common.ports
--- linux-2.6.31/debian.master/config/config.common.ports       2009-08-21 18:39:57.000000000 +0100
+++ linux-2.6.31/debian.master/config/config.common.ports       2009-08-24 18:08:33.000000000 +0100
@@ -1622,6 +1622,7 @@
 # CONFIG_LPARCFG is not set
 # CONFIG_LP_CONSOLE is not set
 CONFIG_LSI_ET1011C_PHY=m
+CONFIG_LSM_MMAP_MIN_ADDR=65536
 CONFIG_LXT_PHY=m
 CONFIG_M25PXX_USE_FAST_READ=y
 CONFIG_MA600_DONGLE=m
------------------------------------------------------------------------------------------------------------------------------------------------------------

2) = [ and from the linux_2.6.31-6.26_2.6.31-7.27.diff.gz#patchfs/linux-2.6.31/debian.master/config/config.common.ubuntu.diff: ]

------------------------------------------------------------------------------------------------------------------------------------------------------------

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/debian.master/config/config.common.ubuntu /tmp/Td2i4nRkP9/linux-2.6.31/debian.master/config/config.common.ubuntu
--- linux-2.6.31/debian.master/config/config.common.ubuntu      2009-08-21 18:39:57.000000000 +0100
+++ linux-2.6.31/debian.master/config/config.common.ubuntu      2009-08-24 18:08:33.000000000 +0100
@@ -1930,6 +1930,7 @@
 CONFIG_LP486E=m
 # CONFIG_LP_CONSOLE is not set
 CONFIG_LSI_ET1011C_PHY=m
+CONFIG_LSM_MMAP_MIN_ADDR=65536
 CONFIG_LTPC=m
 CONFIG_LXT_PHY=m
 CONFIG_LZO_COMPRESS=m

------------------------------------------------------------------------------------------------------------------------------------------------------------

These are the only clues I can offer to the current kernel change!

Revision history for this message

Peter W Bowey (support-pbcomp.com.au) wrote on 2009-08-27:

#17

Download full text (11.5 KiB)

Found some further changes in the kernel update:

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/Documentation/filesystems/afs.txt /tmp/Td2i4nRkP9/linux-2.6.31/Documentation/filesystems/afs.txt
--- linux-2.6.31/Documentation/filesystems/afs.txt 2009-08-21 18:39:55.000000000 +0100
+++ linux-2.6.31/Documentation/filesystems/afs.txt 2009-08-24 18:08:31.000000000 +0100
@@ -23,15 +23,13 @@

(*) Security (currently only AFS kaserver and KerberosIV tickets).

- (*) File reading.
+ (*) File reading and writing.

(*) Automounting.

-It does not yet support the following AFS features:
-
- (*) Write support.
+ (*) Local caching (via fscache).

- (*) Local caching.
+It does not yet support the following AFS features:

(*) pioctl() system call.

@@ -56,7 +54,7 @@
the masks in the following files:

/sys/module/af_rxrpc/parameters/debug
- /sys/module/afs/parameters/debug
+ /sys/module/kafs/parameters/debug

=====
@@ -66,9 +64,9 @@
When inserting the driver modules the root cell must be specified along with a
list of volume location server IP addresses:

- insmod af_rxrpc.o
- insmod rxkad.o
- insmod kafs.o rootcell=cambridge.redhat.com:172.16.18.73:172.16.18.91
+ modprobe af_rxrpc
+ modprobe rxkad
+ modprobe kafs rootcell=cambridge.redhat.com:172.16.18.73:172.16.18.91

The first module is the AF_RXRPC network protocol driver. This provides the
RxRPC remote operation protocol and may also be accessed from userspace. See:
@@ -81,7 +79,7 @@
Once the module has been loaded, more modules can be added by the following
procedure:

- echo add grand.central.org 18.7.14.88:128.2.191.224 >/proc/fs/afs/cells
+ echo add grand.central.org 18.9.48.14:128.2.203.61:130.237.48.87 >/proc/fs/afs/cells

Where the parameters to the "add" command are the name of a cell and a list of
volume location servers within that cell, with the latter separated by colons.
@@ -101,7 +99,7 @@
specify connection to only volumes of those types.

The name of the cell is optional, and if not given during a mount, then the
-named volume will be looked up in the cell specified during insmod.
+named volume will be looked up in the cell specified during modprobe.

Additional cells can be added through /proc (see later section).

@@ -163,14 +161,14 @@

The filesystem maintains an internal database of all the cells it knows and the
IP addresses of the volume location servers for those cells. The cell to which
-the system belongs is added to the database when insmod is performed by the
+the system belongs is added to the database when modprobe is performed by the
"rootcell=" argument or, if compiled in, using a "kafs.rootcell=" argument on
the kernel command line.

Further cells can be added by commands similar to the following:

echo add CELLNAME VLADDR[:VLADDR][:VLADDR]... >/proc/fs/afs/cells
- echo add grand.central.org 18.7.14.88:128.2.191.224 >/proc/fs/afs/cells
+ echo add grand.central.org 18.9.48.14:128.2.203.61:130.237.48.87 >/proc/fs/afs/cells

No other cell database operations are available at this time.

@@ -233,7 +231,7 @@
mount -t afs \%root.afs. /afs
mount -t afs \%cambrid...

Found some further changes in the kernel update:

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/Documentation/filesystems/afs.txt /tmp/Td2i4nRkP9/linux-2.6.31/Documentation/filesystems/afs.txt
--- linux-2.6.31/Documentation/filesystems/afs.txt      2009-08-21 18:39:55.000000000 +0100
+++ linux-2.6.31/Documentation/filesystems/afs.txt      2009-08-24 18:08:31.000000000 +0100
@@ -23,15 +23,13 @@

(*) Security (currently only AFS kaserver and KerberosIV tickets).

- (*) File reading.
+ (*) File reading and writing.

(*) Automounting.

-It does not yet support the following AFS features:
-
- (*) Write support.
+ (*) Local caching (via fscache).

- (*) Local caching.
+It does not yet support the following AFS features:

(*) pioctl() system call.

@@ -56,7 +54,7 @@
 the masks in the following files:

/sys/module/af_rxrpc/parameters/debug
-       /sys/module/afs/parameters/debug
+       /sys/module/kafs/parameters/debug

=====
@@ -66,9 +64,9 @@
 When inserting the driver modules the root cell must be specified along with a
 list of volume location server IP addresses:

-       insmod af_rxrpc.o
-       insmod rxkad.o
-       insmod kafs.o rootcell=cambridge.redhat.com:172.16.18.73:172.16.18.91
+       modprobe af_rxrpc
+       modprobe rxkad
+       modprobe kafs rootcell=cambridge.redhat.com:172.16.18.73:172.16.18.91

The first module is the AF_RXRPC network protocol driver.  This provides the
 RxRPC remote operation protocol and may also be accessed from userspace.  See:
@@ -81,7 +79,7 @@
 Once the module has been loaded, more modules can be added by the following
 procedure:

-       echo add grand.central.org 18.7.14.88:128.2.191.224 >/proc/fs/afs/cells
+       echo add grand.central.org 18.9.48.14:128.2.203.61:130.237.48.87 >/proc/fs/afs/cells

Where the parameters to the "add" command are the name of a cell and a list of
 volume location servers within that cell, with the latter separated by colons.
@@ -101,7 +99,7 @@
 specify connection to only volumes of those types.

The name of the cell is optional, and if not given during a mount, then the
-named volume will be looked up in the cell specified during insmod.
+named volume will be looked up in the cell specified during modprobe.

Additional cells can be added through /proc (see later section).

@@ -163,14 +161,14 @@

The filesystem maintains an internal database of all the cells it knows and the
 IP addresses of the volume location servers for those cells.  The cell to which
-the system belongs is added to the database when insmod is performed by the
+the system belongs is added to the database when modprobe is performed by the
 "rootcell=" argument or, if compiled in, using a "kafs.rootcell=" argument on
 the kernel command line.

Further cells can be added by commands similar to the following:

echo add CELLNAME VLADDR[:VLADDR][:VLADDR]... >/proc/fs/afs/cells
-       echo add grand.central.org 18.7.14.88:128.2.191.224 >/proc/fs/afs/cells
+       echo add grand.central.org 18.9.48.14:128.2.203.61:130.237.48.87 >/proc/fs/afs/cells

No other cell database operations are available at this time.

@@ -233,7 +231,7 @@
 mount -t afs \%root.afs. /afs
 mount -t afs \%cambridge.redhat.com:root.cell. /afs/cambridge.redhat.com/

-echo add grand.central.org 18.7.14.88:128.2.191.224 > /proc/fs/afs/cells
+echo add grand.central.org 18.9.48.14:128.2.203.61:130.237.48.87 > /proc/fs/afs/cells
 mount -t afs "#grand.central.org:root.cell." /afs/grand.central.org/
 mount -t afs "#grand.central.org:root.archive." /afs/grand.central.org/archive
 mount -t afs "#grand.central.org:root.contrib." /afs/grand.central.org/contrib

----------------------------------------------------------------------------------------------------

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/Documentation/filesystems/proc.txt /tmp/Td2i4nRkP9/linux-2.6.31/Documentation/filesystems/proc.txt
--- linux-2.6.31/Documentation/filesystems/proc.txt     2009-08-21 18:39:55.000000000 +0100
+++ linux-2.6.31/Documentation/filesystems/proc.txt     2009-08-24 18:08:31.000000000 +0100
@@ -1167,13 +1167,11 @@
 3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
 ------------------------------------------------------

-This file can be used to adjust the score used to select which processes should
-be killed in an out-of-memory situation.  The oom_adj value is a characteristic
-of the task's mm, so all threads that share an mm with pid will have the same
-oom_adj value.  A high value will increase the likelihood of this process being
-killed by the oom-killer.  Valid values are in the range -16 to +15 as
-explained below and a special value of -17, which disables oom-killing
-altogether for threads sharing pid's mm.
+This file can be used to adjust the score used to select which processes
+should be killed in an  out-of-memory  situation.  Giving it a high score will
+increase the likelihood of this process being killed by the oom-killer.  Valid
+values are in the range -16 to +15, plus the special value -17, which disables
+oom-killing altogether for this process.

The process to be killed in an out-of-memory situation is selected among all others
 based on its badness score. This value equals the original memory size of the process
@@ -1187,9 +1185,6 @@
 are the prime candidates to be killed. Having only one 'hungry' child will make
 parent less preferable than the child.

-/proc/<pid>/oom_adj cannot be changed for kthreads since they are immune from
-oom-killing already.
-
 /proc/<pid>/oom_score shows process' current badness score.

The following heuristics are then applied:

(nothing listed here?)

-----------------------------------------------------------------------------------------------------------

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/Documentation/vm/00-INDEX /tmp/Td2i4nRkP9/linux-2.6.31/Documentation/vm/00-INDEX
--- linux-2.6.31/Documentation/vm/00-INDEX      2009-08-21 18:39:55.000000000 +0100
+++ linux-2.6.31/Documentation/vm/00-INDEX      2009-08-24 18:08:31.000000000 +0100
@@ -6,6 +6,8 @@
        - various information on memory balancing.
 hugetlbpage.txt
        - a brief summary of hugetlbpage support in the Linux kernel.
+ksm.txt
+       - how to use the Kernel Samepage Merging feature.
 locking
        - info on how locking and synchronization is done in the Linux vm code.
 numa

-----------------------------------------------------------------------------------

diff -Nru /tmp/FNdEZPHKHo/linux-2.6.31/Documentation/vm/ksm.txt /tmp/Td2i4nRkP9/linux-2.6.31/Documentation/vm/ksm.txt
--- linux-2.6.31/Documentation/vm/ksm.txt       1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.31/Documentation/vm/ksm.txt       2009-08-24 18:08:31.000000000 +0100
@@ -0,0 +1,89 @@
+How to use the Kernel Samepage Merging feature
+----------------------------------------------
+
+KSM is a memory-saving de-duplication feature, enabled by CONFIG_KSM=y,
+added to the Linux kernel in 2.6.32.  See mm/ksm.c for its implementation,
+and http://lwn.net/Articles/306704/ and http://lwn.net/Articles/330589/
+
+The KSM daemon ksmd periodically scans those areas of user memory which
+have been registered with it, looking for pages of identical content which
+can be replaced by a single write-protected page (which is automatically
+copied if a process later wants to update its content).
+
+KSM was originally developed for use with KVM (where it was known as
+Kernel Shared Memory), to fit more virtual machines into physical memory,
+by sharing the data common between them.  But it can be useful to any
+application which generates many instances of the same data.
+
+KSM only merges anonymous (private) pages, never pagecache (file) pages.
+KSM's merged pages are at present locked into kernel memory for as long
+as they are shared: so cannot be swapped out like the user pages they
+replace (but swapping KSM pages should follow soon in a later release).
+
+KSM only operates on those areas of address space which an application
+has advised to be likely candidates for merging, by using the madvise(2)
+system call: int madvise(addr, length, MADV_MERGEABLE).
+
+The app may call int madvise(addr, length, MADV_UNMERGEABLE) to cancel
+that advice and restore unshared pages: whereupon KSM unmerges whatever
+it merged in that range.  Note: this unmerging call may suddenly require
+more memory than is available - possibly failing with EAGAIN, but more
+probably arousing the Out-Of-Memory killer.
+
+If KSM is not configured into the running kernel, madvise MADV_MERGEABLE
+and MADV_UNMERGEABLE simply fail with EINVAL.  If the running kernel was
+built with CONFIG_KSM=y, those calls will normally succeed: even if the
+the KSM daemon is not currently running, MADV_MERGEABLE still registers
+the range for whenever the KSM daemon is started; even if the range
+cannot contain any pages which KSM could actually merge; even if
+MADV_UNMERGEABLE is applied to a range which was never MADV_MERGEABLE.
+
+Like other madvise calls, they are intended for use on mapped areas of
+the user address space: they will report ENOMEM if the specified range
+includes unmapped gaps (though working on the intervening mapped areas),
+and might fail with EAGAIN if not enough memory for internal structures.
+
+Applications should be considerate in their use of MADV_MERGEABLE,
+restricting its use to areas likely to benefit.  KSM's scans may use
+a lot of processing power, and its kernel-resident pages are a limited
+resource.  Some installations will disable KSM for these reasons.
+
+The KSM daemon is controlled by sysfs files in /sys/kernel/mm/ksm/,
+readable by all but writable only by root:

+max_kernel_pages - set to maximum number of kernel pages that KSM may use
+                   e.g. "echo 2000 > /sys/kernel/mm/ksm/max_kernel_pages"
+                   Value 0 imposes no limit on the kernel pages KSM may use;
+                   but note that any process using MADV_MERGEABLE can cause
+                   KSM to allocate these pages, unswappable until it exits.
+                   Default: 2000 (chosen for demonstration purposes)
+
+pages_to_scan    - how many present pages to scan before ksmd goes to sleep
+                   e.g. "echo 200 > /sys/kernel/mm/ksm/pages_to_scan"
+                   Default: 200 (chosen for demonstration purposes)
+
+sleep_millisecs  - how many milliseconds ksmd should sleep before next scan
+                   e.g. "echo 20 > /sys/kernel/mm/ksm/sleep_millisecs"
+                   Default: 20 (chosen for demonstration purposes)
+
+run              - set 0 to stop ksmd from running but keep merged pages,
+                   set 1 to run ksmd e.g. "echo 1 > /sys/kernel/mm/ksm/run",
+                   set 2 to stop ksmd and unmerge all pages currently merged,
+                         but leave mergeable areas registered for next run
+                   Default: 1 (for immediate use by apps which register)
+
+The effectiveness of KSM and MADV_MERGEABLE is shown in /sys/kernel/mm/ksm/:
+
+pages_shared     - how many shared unswappable kernel pages KSM is using
+pages_sharing    - how many more sites are sharing them i.e. how much saved
+pages_unshared   - how many pages unique but repeatedly checked for merging
+pages_volatile   - how many pages changing too fast to be placed in a tree
+full_scans       - how many times all mergeable areas have been scanned
+
+A high ratio of pages_sharing to pages_shared indicates good sharing, but
+a high ratio of pages_unshared to pages_sharing indicates wasted effort.
+pages_volatile embraces several different kinds of activity, but a high
+proportion there would also indicate poor use of madvise MADV_MERGEABLE.
+
+Izik Eidus,
+Hugh Dickins, 30 July 2009
-----------------------------------------------------------------------------------

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GriFF3n (griff3ng) wrote on 2009-08-31:

#18

Was having the same problem with kernel 2.6.31-7-generic. Updated to 2.6.31-8-generic and problem fixed.

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tx (372046933-qq) wrote on 2011-01-21:

#19

2.6.32-27-generic has the same PROBLEM

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