On 10/20/15 at 12:32am, Dangyi Liu wrote:
The initial reason why I want to add this configuration is that some
boot parameter would break kdump. For example, kernel developers may use slub_debug, which
will cost extra memory. Normal users may use quiet, which makes kdump debug more
difficult. It's necessary that in some cases admins want to remove some parameters
from cmdline.
And some parameters such as "crash kernel" should never be applied to the
second kernel. We can remove them in kdumpctl directly.
OK, if it becomes a one by one check. Let's evaluate each of them, how
about panic_on_warn? This one will nested panic in kdump kernel because
of a warn. This can't be opened.
Next are hugepagexx. This could be opened again by user for curiosity or
efficiency and similar to slub_debug if enough crashkernel memory is
reserved. quiet, should be the same way.
This is about my 1st question. How about the 2nd? About the 3rd
question, that is a annoy and need be considered.
> 在 2015年10月20日,上午11:46,Baoquan He <bhe(a)redhat.com> 写道:
>
>> On 10/19/15 at 04:29pm, Dangyi Liu wrote:
>> Use KDUMP_COMMANDLINE_REMOVE config instead of hardcode them in
>> kdumpctl. System admins can also specify what to remove as they like.
>>
>> However, this patch makes a change that kdump command line from
>> KDUMP_COMMANDLINE will not be trimmed any more.
>>
>> Signed-off-by: Dangyi Liu <dliu(a)redhat.com>
>> Cc: Dave Young <dyoung(a)redhat.com>
>> Cc: Minfei Huang <mhuang(a)redhat.com>
>
> OK, I didn't follow this issue earlier. But I have some questions.
> Adding KDUMP_COMMANDLINE_REMOVE to put those kernel-parameters under
> /etc/sysconfig means they can be switched by users or admins surely, just
> like we do in KDUMP_COMMANDLINE_APPEND. I want to remind that all of
> stuffs put in KDUMP_COMMANDLINE_REMOVE are proved helpless for vmcore
> dumping. Turning one or several of them could cause bugs, but turning
> them off can prevent bugs and don't incur dumping issues. Then I am
> wondering why we want them to be turned on by users. E.g for
> "crashkernel" could you tell in what cases user want to turn it on in
> kdump kernel?
>
> 2nd question is if we all agree to put them in KDUMP_COMMANDLINE_REMOVE
> do users know what they are used for and why they need remove and in
> which case they can be opened? Do you have a plan to elaborate each of
> them?
>
> 3rd, I saw you were confused about which one should be handled firstly
> about KDUMP_COMMANDLINE_APPEND and KDUMP_COMMANDLINE_REMOVE. This is a
> kind of torture we make to put on ourselves. We give users of kdump too
> many options.
>
> I personally do not like this idea. But I don't oppose it strongly since
> people bring it up.
>
> Thanks
> Baoquan
>
>> ---
>> kdump.sysconfig | 4 ++++
>> kdump.sysconfig.i386 | 4 ++++
>> kdump.sysconfig.ppc64 | 4 ++++
>> kdump.sysconfig.ppc64le | 4 ++++
>> kdump.sysconfig.s390x | 4 ++++
>> kdump.sysconfig.x86_64 | 4 ++++
>> kdumpctl | 3 +--
>> 7 files changed, 25 insertions(+), 2 deletions(-)
>>
>> diff --git a/kdump.sysconfig b/kdump.sysconfig
>> index effe466..f93aa25 100644
>> --- a/kdump.sysconfig
>> +++ b/kdump.sysconfig
>> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>> # /proc/cmdline
>> KDUMP_COMMANDLINE=""
>>
>> +# This variable lets us remove arguments from the current kdump commandline.
>> +# This only works when the command line is taken from /proc/cmdline.
>> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
>> +
>> # This variable lets us append arguments to the current kdump commandline
>> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>> KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices"
>> diff --git a/kdump.sysconfig.i386 b/kdump.sysconfig.i386
>> index bb7a6e5..b6ca58b 100644
>> --- a/kdump.sysconfig.i386
>> +++ b/kdump.sysconfig.i386
>> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>> # /proc/cmdline
>> KDUMP_COMMANDLINE=""
>>
>> +# This variable lets us remove arguments from the current kdump commandline.
>> +# This only works when the command line is taken from /proc/cmdline.
>> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
>> +
>> # This variable lets us append arguments to the current kdump commandline
>> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>> KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices numa=off
udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>> diff --git a/kdump.sysconfig.ppc64 b/kdump.sysconfig.ppc64
>> index dd09598..de2364e 100644
>> --- a/kdump.sysconfig.ppc64
>> +++ b/kdump.sysconfig.ppc64
>> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>> # /proc/cmdline
>> KDUMP_COMMANDLINE=""
>>
>> +# This variable lets us remove arguments from the current kdump commandline.
>> +# This only works when the command line is taken from /proc/cmdline.
>> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
>> +
>> # This variable lets us append arguments to the current kdump commandline
>> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>> KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>> diff --git a/kdump.sysconfig.ppc64le b/kdump.sysconfig.ppc64le
>> index dd09598..de2364e 100644
>> --- a/kdump.sysconfig.ppc64le
>> +++ b/kdump.sysconfig.ppc64le
>> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>> # /proc/cmdline
>> KDUMP_COMMANDLINE=""
>>
>> +# This variable lets us remove arguments from the current kdump commandline.
>> +# This only works when the command line is taken from /proc/cmdline.
>> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
>> +
>> # This variable lets us append arguments to the current kdump commandline
>> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>> KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 noirqdistrib reset_devices
cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10
rootflags=nofail kvm_cma_resv_ratio=0 transparent_hugepage=never"
>> diff --git a/kdump.sysconfig.s390x b/kdump.sysconfig.s390x
>> index b103a88..9fce28d 100644
>> --- a/kdump.sysconfig.s390x
>> +++ b/kdump.sysconfig.s390x
>> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>> # /proc/cmdline
>> KDUMP_COMMANDLINE=""
>>
>> +# This variable lets us remove arguments from the current kdump commandline.
>> +# This only works when the command line is taken from /proc/cmdline.
>> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
>> +
>> # This variable lets us append arguments to the current kdump commandline
>> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>> KDUMP_COMMANDLINE_APPEND="nr_cpus=1 cgroup_disable=memory numa=off
udev.children-max=2 panic=10 rootflags=nofail transparent_hugepage=never"
>> diff --git a/kdump.sysconfig.x86_64 b/kdump.sysconfig.x86_64
>> index 7991d68..fc2961d 100644
>> --- a/kdump.sysconfig.x86_64
>> +++ b/kdump.sysconfig.x86_64
>> @@ -14,6 +14,10 @@ KDUMP_KERNELVER=""
>> # /proc/cmdline
>> KDUMP_COMMANDLINE=""
>>
>> +# This variable lets us remove arguments from the current kdump commandline.
>> +# This only works when the command line is taken from /proc/cmdline.
>> +KDUMP_COMMANDLINE_REMOVE="crashkernel hugepages hugepagesz panic_on_warn
slub_debug"
>> +
>> # This variable lets us append arguments to the current kdump commandline
>> # As taken from either KDUMP_COMMANDLINE above, or from /proc/cmdline
>> KDUMP_COMMANDLINE_APPEND="irqpoll nr_cpus=1 reset_devices
cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail
acpi_no_memhotplug transparent_hugepage=never"
>> diff --git a/kdumpctl b/kdumpctl
>> index 9f7e56b..3b0760b 100755
>> --- a/kdumpctl
>> +++ b/kdumpctl
>> @@ -102,11 +102,10 @@ prepare_cmdline()
>> local cmdline;
>> if [ -z "$KDUMP_COMMANDLINE" ]; then
>> cmdline=`cat /proc/cmdline`
>> + cmdline=`remove_cmdline_param "$cmdline"
${KDUMP_COMMANDLINE_REMOVE}`
>> else
>> cmdline=${KDUMP_COMMANDLINE}
>> fi
>> - cmdline=`remove_cmdline_param "$cmdline" crashkernel hugepages
hugepagesz panic_on_warn slub_debug`
>> -
>>
>> cmdline="${cmdline} ${KDUMP_COMMANDLINE_APPEND}"
>>
>> --
>> 2.4.3
>>
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