Previously if a target need mount info, the relevant mount options
are got from /proc/mounts by below command:
findmnt -k -f -n -r -o OPTIONS $_dev
This will bring problems. Since /proc/mounts will give out a set
which contains each option. Some options have value specified by
user, some options just have default value if user doesn't specify.
If some mount options are not supported very well, bugs occured.
The more options, the worse.
So in this patch, we try to check fstab to get mount options firstly,
this give user a chance to decide which options they really want.
If they don't give a fstab entry, then we trust all options in
/proc/mounts.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Upstream makedumpfile contains some sample eppic scripts for reference.
Now pull the whole scripts directory into kexec-tools-eppic package.
Signed-off-by: WANG Chao <chaowang@redhat.com>
This patch changes restart of kdump service from cpu online/offline events
to cpu add/remove events.
Some people have complained that they are running cpu online/offline tests
at high frequency and kdump restarts at high frequency and systemd disables
the service. As a temporary fix, we committed a patch to never disable
kdump service.
In general it probably is a good idea to restart kdump service on cpu
add/remove events.
Toshi Kani confirmed following.
- File for /sys/devices/system/cpu/cpuX/crash_notes will be created first
before ADD event goes out. That means we can not miss creating EFL notes
for newly created cpu.
- For REMOVE event files under /sys/devices/system/cpu/cpuX/ are removed
first and then REMOVE event goes out. That means we will remove the elf
note header for removed cpu.
- There are some race conditions like a cpu is removed but system crashes
before kdump service restarts. In that case vmcore.c has to be more robust
to be able to inspect elf notes and discard empty ones.
Also it is possible that after cpu remove, crash notes memory got reused
for something else and after crash vmcore.c might see some random data.
It does basic size checks and discards elf notes if checks don't pass.
Above rance conditions can happen even with OFFLINE event and there is
no good way to remove these altogether. So making vmcore.c more robust
is the right solution here.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: WANG Chao <chaowang@redhat.com>
Backport the following commit from kexec-tools upstream:
commit 45b33eb
Author: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Date: Fri Jul 25 17:07:49 2014 +0200
ppc64/kdump: Fix ELF header endianess
The ELF header created among the loading of the kdump kernel should be
flagged using the current endianess and not always as big endian.
Without this patch the data exposed in /proc/vmcore are not readable when
running in LE mode.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
This is part of the work to enable ppc64le.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Backport the following commit from upstream kexec-tools:
commit 335bad7
Author: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Date: Tue Jul 22 18:22:28 2014 +0200
kexec/ppc64: disabling exception handling when building the purgatory
Some Linux distributions would like to turn on the GCC exception handling
by default. As this option introduces symbols in the built code that are
defined in a separate shared library, this is not a good idea to have such
an option activated when building the purgatory.
This patch forces the exception handling to be turned off when building the
purgatory on ppc64 BE and LE.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
This is part of the work to enable ppc64le.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Backport the following commit from upstream kexec-tools:
commit 2ca2203
Author: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Date: Mon Jun 16 14:42:43 2014 +0200
kexec/ppc64: move to device tree version 17
Kernel commit e6a6928c3ea1d0195ed75a091e345696b916c09b changed the way the
device tree is processed in the kernel. Now version 2 is no more supported.
This patch move the version of the device tree generated in ppc64
environment from 2 to 17, allowing to kexec kernel 3.16.
In addition, automates the define of NEED_STRUCTURE_BLOCK_EXTRA_PAD which
should not be set for DT version 16 and above.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
This is part of the work to enable ppc64le.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Now kexec file based syscall can be used with secureboot enabled machines.
Automatically switch to using new syscall if secureboot is enabled on the
machine.
Also remove the old message where kdump service failed if secureboot is
enabled. That's not the case anymore.
v2:
Renamed "secureboot" to "Secure Boot" in user visible message.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Currently old kexec syscall denies unloading a kernel if secureboot is enabled.
I think this is not right behavior and should be changed. But for now, use
new syscall if secureboot is enabled and that allows unloading kernel.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Does anybody know why are we redirecting stderr to /dev/null when using
kexec load/unload commands? This sounds wrong to me. In case of error I
have no idea what went wrong.
Systemctl already puts all the information in journal. So if we are worried
that user will be bombarded with error messages, that should not be a concern.
So do not redirect stderr to /dev/null.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
This is a back port from upstream.
commit 046d1755d2bd723a11a180c265e61a884990712e
Author: Vivek Goyal <vgoyal@redhat.com>
Date: Mon Aug 18 11:22:32 2014 -0400
kexec: Provide an option to use new kexec system call
Hi,
This is v2 of the patch. Since v1, I moved syscall implemented check littler
earlier in the function as per the feedback.
Now a new kexec syscall (kexec_file_load()) has been merged in upstream
kernel. This system call takes file descriptors of kernel and initramfs
as input (as opposed to list of segments to be loaded). This new system
call allows for signature verification of the kernel being loaded.
One use of signature verification of kernel is secureboot systems where
we want to allow kexec into a kernel only if it is validly signed by
a key system trusts.
This patch provides and option --kexec-file-syscall (-s), to force use of
new system call for kexec. Default is to continue to use old syscall.
Currently only bzImage64 on x86_64 can be loaded using this system call.
As kernel adds support for more arches and for more image types, kexec-tools
can be modified accordingly.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Since we have added kdump anaconda addon, thus removing firstboot module
User can setup kdump in anaconda install phase, and change the kdump.conf
details in s-c-kdump
Delete the firstboot po files as well.
Signed-off-by: Dave Young <dyoung@redhat.com>
Bao noticed the following systemd warning:
systemd[1]: [/usr/lib/systemd/system/emergency.service:17] Executable path is
not absolute, ignoring: systemctl --no-block isolate kdump-error-handler.service
It turns out that now systemd doesn't allow relative path for an executable, we
must adapt that, make the change.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Tested-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Resolves: rhbz#1131169
Zbigniew (systemd developer) pointed out that our udev rules should
install to /usr/lib/ not /etc. Because /etc is supposed to be used by
sysadmins only and package should install by default into /usr/lib.
As advised here:
http://www.freedesktop.org/software/systemd/man/udev.html#Rules%20Files
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Node could be referenced by short hostname (hostname -s) in cluster
configuration:
[root@virt-068 /]# pcs status nodes
Pacemaker Nodes:
Online: virt-066 virt-067 virt-068
Standby:
Offline:
We didn't know it before. Martin noticed the kdump failure, and provide
this fix. Thanks to Martin.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Tested-by: Martin Juricek <mjuricek@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Since we've use systemd to control the shutdown path, there's not need
for us to unmount the filesystem, systemd will do that for us just like
it does in a normal boot.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
It's more safe to use systemd (init) to control the shutdown path for us
in either reboot or power off or halt action.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
When there's no kdump initramfs for lsinitrd to inspect with, there will
be an error:
# kdumpctl start
/boot/initramfs-3.16.0-rc7+kdump.img does not exist
Usage: lsinitrd [options] [<initramfs file> [<filename> [<filename> [...] ]]]
Usage: lsinitrd [options] -k <kernel version>
-h, --help print a help message and exit.
-s, --size sort the contents of the initramfs by size.
-m, --mod list modules.
-f, --file <filename> print the contents of <filename>.
-k, --kver <kernel version> inspect the initramfs of <kernel version>.
No kdump initial ramdisk found.
Rebuilding /boot/initramfs-3.16.0-rc7+kdump.img
[..]
In addition, lsinitrd is a slow operation. We only run it when it's
fadump mode, to speed up in kdump mode.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
If one target address is not local and its route is different than
default gateway, the specific route to this target address need be
added. E.g, target is 192.168.200.222.
sh> ip route show
default via 192.168.122.1 dev eth0 proto static metric 1024
192.168.200.0/24 via 192.168.100.222 dev ens10 proto static metric 1
In this patch, get the route to the specific target address and store
it as cmdline, here is /etc/cmdline.d/45-route-static.conf. And the
route options are separated by semicolon like below. Then the stored
route can be parsed when kdump kernel boot up.
192.168.200.0/24:192.168.100.222:ens10
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
In fadump, in case of failure while rebuilding initrd, the error status
is not handled properly. See code snippet below:
$MKDUMPRD $target_initrd_tmp --rebuild $TARGET_INITRD --kver $kdump_kver \
-i /tmp/fadump.initramfs /etc/fadump.initramfs
rm -f /tmp/fadump.initramfs
if [ $? != 0 ]; then
echo "mkdumprd: failed to rebuild initrd with fadump support" >&2
return 1
fi
This patch fixes this issue
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This patch introduce a new kdump-capture.service which is used to run
kdump.sh.
kdump-capture.service has OnFailure=emergency.target and
OnFailureIsolate=yes set. When kdump.sh fails, the kdump emergency
service will be triggered and enter the error handling path.
In 2nd kernel, the default target for systemd is initrd.target, so we
put kdump-capture.service in initrd.target.wants/ and by that, system
will start kdump-capture as part of the boot process.
kdump.sh used to run in dracut-pre-pivot hook. Now kdump-capture.service
is placed after dracut-pre-pivot.service and other dependencies are all
copied from dracut-pre-pivot.service. So the start point of
kdump.sh will be almost the same as it used to be.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Now upon failure kdump script might not be called at all and it might
not be able to execute default action. It results in a hang.
Because we disable emergency shell and rely on kdump.sh being invoked
through dracut-pre-pivot hook. But it might happen that we never call
into dracut-pre-pivot hook because certain systemd targets could not
reach due to failure in their dependencies. In those cases error
handling code does not run and system hangs. For example:
sysroot-var-crash.mount --> initrd-root-fs.target --> initrd.target \
--> dracut-pre-pivot.service --> kdump.sh
If /sysroot/var/crash mount fails, initrd-root-fs.target will not be
reached. And then initrd.target will not be reached,
dracut-pre-pivot.service wouldn't run. Finally kdump.sh wouldn't run.
To solve this problem, we need to separate the error handling code from
dracut-pre-pivot hook, and every time when a failure shows up, the
separated code can be called by the emergency service.
By default systemd provides an emergency service which will drop us into
shell every time upon a critical failure. It's very convenient for us to
re-use the framework of systemd emergency, because we don't have to
touch the other parts of systemd. We can use our own script instead of
the default one.
This new scheme will overwrite emergency shell and replace with kdump
error handling code. And this code will do the error handling as needed.
Now, we will not rely on dracut-pre-pivot hook running always. Instead
whenever error happens and it is serious enough that emergency shell
needed to run, now kdump error handler will run.
dracut-emergency is also replaced by kdump error handler and it's
enabled again all the way down. So all the failure (including systemd
and dracut) in 2nd kernel could be captured, and trigger kdump error
handler.
dracut-initqueue is a special case, which calls "systemctl start
emergency" directly, not via "OnFailure=emergency". In case of failure,
emergency is started, but not in a isolation mode, which means
dracut-initqueue is still running. On the other hand, emergency will
call dracut-initqueue again when default action is dump_to_rootfs.
systemd would block on the last dracut-initqueue, waiting for the first
instance to exit, which leaves us hang. It looks like the following:
dracut-initqueue (running)
--> call dracut-emergency:
--> dracut-emergency (running)
--> kdump-error-handler.sh (running)
--> call dracut-initqueue:
--> blocking and waiting for the original instance to exit.
To fix this, I'd like to introduce a wrapper emergency service. This
emegency service will replace both the systemd and dracut emergency. And
this service does nothing but to isolate to real kdump error handler
service:
dracut-initqueue (running)
--> call dracut-emergency:
--> dracut-emergency isolate to kdump-error-handler.service
--> dracut-emergency and dracut-initqueue will both be stopped
and kdump-error-handler.service will run kdump-error-handler.sh.
In a normal failure case, this still works:
foo.service fails
--> trigger emergency.service
--> emergency.service isolates to kdump-error-handler.service
--> kdump-error-handler.service will run kdump-error-handler.sh
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Now when mount in /etc/fstab fails, systemd would not consider it as
critical and it would continue to boot. In fact, emergency service is
triggered, but not in a isolation mode, and it results in the emergency
service getting shutdown at some point later of the boot process. We
need isolation otherwise we won't see any emergency service.
That is because in kdump initramfs, mount units specified in /etc/fstab
are required by "local-fs.target". When any of these mounts fails,
local-fs.target fails.
For kdump initramfs, we need to isolate to emergency service on any of
the mount failure, that said, every service should be stopped and onlu
emergency service would run. But local-fs.target won't trigger that on
its failure. That means in case of mount failure, local-fs.target also
enters failure state, but all the service will continue without any
interruption.
After digging looking into source code of systemd-fstab-generator. I
find "x-initrd.mount" using in initramfs mount, will make the mount
units required by "initrd-root-fs.target" rather than it's used to be
"local-fs.target".
"initrd-root-fs.target" is suitable to us because if it fails, it will
isolate to emergency service. That means in case of any mount failure,
the emergeny service will start and everything else will stop. We want
this effect because we need to take kdump fail-safe action when there's
a mount failure.
From systemd unit point of view, "initrd-root-fs.target" has
OnFailureIsolate=yes, but "local-fs.target" doesn't. From
systemd.unit(5):
OnFailureIsolate=
Takes a boolean argument. If true, the unit listed in OnFailure=
will be enqueued in isolation mode, i.e. all units that are not its
dependency will be stopped. If this is set, only a single unit may
be listed in OnFailure=. Defaults to false.
NOTE: Harald who contributed "x-initrd.mount" in systemd, confirmed that
this feature will stay.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This patch does the following change in 2nd kernel:
- dump target is mounted under /sysroot
With this change, we don't need to track what we've mounted in 2nd
kernel. We can just umount recursively every mount in /sysroot by
command:
umount -R /sysroot
It's very convenient to do so, because it's hard to track what we've
mounted when we're in error handling path (later patches). So mount
everything under /sysroot is reasonable and practical for us.
Also clean up a bit along with this patch.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Extract functions from kdump.sh, and construct kdump-lib-initramfs.sh as
kdump common functions/varaibles library.
kdump-lib-initramfs.sh will include kdump-lib.sh, because it will use
the functions from there. IOW, kdump-lib-initramfs.sh will be a superset
of kdump-lib.sh
So after this cleanup:
- scripts running in 1st kernel only have to include kdump-lib.sh
- scripts running in 2nd kernel only have to include kdump-lib-initramfs.sh
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Recently somebody reported an issue where vmcore-dmesg.txt was saved
successfully but later saving vmcore failed to due to lack of space on disk.
System rebooted but after reboot there was nothing on disk. Not even
vmcore-dmesg.txt.
Issue a sync after saving vmcore-dmesg.txt to solve this issue.
I think this is happening because we are doing "reboot -f" instead of going
through systemd reboot path. Anyway, doing a sync now should take care of
this.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: WANG Chao <chaowang@redhat.com>
Resending this patch by updating 'fadump control flow' to reflect
the latest changes.
This patch adds fadump howto document to kexec-tools. The document
is prepared in reference to kexec-kdump-howto.txt document.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
The script dracut-kdump.sh is responsible for capturing vmcore during
second kernel boot. Currently this script gets installed into kdump
initrd as part of kdumpbase dracut module.
With fadump support, 'dracut-kdump.sh' script also gets installed into
default initrd to capture vmcore generated by firmware assisted dump.
Thus in fadump case, the same initrd is going to be used for normal
boot as well as boot after system crash. Hence a check is required to
see if it is a normal boot or boot after crash.
A new node "ibm,kernel-dump" is added, to the device tree, by firmware
to notify kernel if it is booting after crash. The below patch adds a
check for this node before executing steps to capture vmcore. This
check will help bypassing the vmcore capture steps during normal boot
process.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
The current kdump infrastructure builds a separate initrd which then
gets loaded into memory by kexec-tools for use by kdump kernel. But
firmware assisted dump (FADUMP) does not use kexec-based approach.
After crash, firmware reboots the partition and loads grub loader
like the normal booting process does. Hence in the FADUMP approach,
the second kernel (after crash) will always use the default initrd
(OS built). So, to support FADUMP, change is required, as in to add
dump capturing steps, in this initrd.
The current kdumpctl script implementation already has the code to
build initrd using mkdumprd. This patch uses the new '--rebuild'
option introduced, in dracut, to incrementally build the initramfs
image. Before rebuilding, we may need to probe the initrd image for
fadump support, to avoid rebuilding the initrd image multiple times
unnecessarily. This can be done using "lsinitrd" tool with the newly
proposed '--mod' option & inspecting the presence of "kdumpbase" in
the list of modules of default initrd image. We rebuild the image if
only "kdumpbase" module is missing in the initrd image. Also, before
rebuilding, a backup of default initrd image is taken.
Kexec-tools package in rhel7 is now enhanced to insert a out-of-tree
kdump module for dracut, which is responsible for adding vmcore
capture steps into initrd, if dracut is invoked with "IN_KDUMP"
environment variable set to 1. mkdumprd script exports "IN_KDUMP=1"
environment variable before invoking dracut to build kdump initrd.
This patch relies on this current mechanism of kdump init script.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
During service kdump stop, if firmware assisted dump is enabled
and running, then stop firmware assisted dump by echo'ing 0 to
'/sys/kernel/fadump_registered' file.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
During service kdump start, if firmware assisted dump is not enabled then
fallback to starting of existing kexec based kdump. If firmware assisted
is enabled but not running, then start firmware assisted dump by echo'ing
1 to '/sys/kernel/fadump_registered' file.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This patch enables kdump script to check if firmware-assisted dump is
enabled or not by reading value from '/sys/kernel/fadump_enabled'. The
determine_dump_mode() routine sets dump_mode to 'fadump', if fadump is
enabled. By default, dump_mode is set to 'kdump' mode.
Modify status routine to check if firmware assisted dump is registered
or not by reading value from '/sys/kernel/fadump_registered' file. If
it is set to '1' then return status=0 else return status=1.
0 <= Firmware assisted is enabled and running
1 <= Firmware assisted is enabled but not running
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
We met a problem that eth0 ends up being eth1 and eth1 being eth0
between 1st and 2nd kernel. Because we pass ifname=eth0:$mac to force
it's named eth0 and since "eth0"is already taken by the other NIC, udev
fails to bring up the NIC we want, thus kdump fails.
kernel assigned network interface names are not persistent. So if first
kernel is using kernel assigned interface names, then force it to use
"kdump-" prefixed names in second kernel.
For ethX, we put a prefix "kdump-" before it, so in 2nd kernel, ethX
will name to "kdump-ethX". So that we can avoid the naming conflict.
We only need to change the ethernet card name, that means, for bridge,
vlan, bond, team devices' names , we never prefix them. Because these
names are assigned when they're created by userspace.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
We handle different types of device for vlan. For each type, it should
write different options for vlan.conf in each control path.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This cleanup patch removes unnecessary keyword "function" at all places in
kdumpctl script. Also, corrects couple of typos in the script.
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Vivek suggested we should display message while waiting for the lock,
because the waiting could be long and user will have no idea what's
going on.
So we will repeat the following message every 5 seconds while waiting:
"Another app is currently holding the kdump lock; waiting for it to exit..."
Thanks Vivek for providing a more comprehensive message.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This is a backport of the following upstream commit.
commit 0b732828091a545185ad13d0b2e6800600788d61
Author: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Date: Tue Jun 10 13:57:29 2014 +0900
[PATCH 3/3] Stop maximizing the bitmap buffer to reduce the risk of OOM.
We tried to maximize the bitmap buffer to get the best performance,
but the performance degradation caused by multi-cycle processing
looks very small according to the benchmark on 2TB memory:
https://lkml.org/lkml/2013/3/26/914
This result means we don't need to make an effort to maximize the
bitmap buffer, it will just increase the risk of OOM.
This patch sets a small fixed value (4MB) as a safety limit,
it may be safer and enough in most cases.
Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
