Re: [PATCH] kdump fails loading if default action is dump_to_rootfs when disk is mounted on save path

[Vivek Goyal]

On Thu, Feb 20, 2014 at 02:00:54PM +0800, Baoquan He wrote:
> kdump now defaults to only dump vmcore to the root partition in the
> /var/crash directory. This is problematic when /var is a separate
> file system because this makes saved vmcore hidden since one can
> not unmount /var even in single user mode. This also has the potential
> of blindly filling the root file system without out a clue as to why.
>
> Now fix this by failing the loading of kdump kernel if default action
> is dump_to_rootfs while different disk is mounted on save path.

Hi Bao,

Few things.

- First of all, it does not matter what's the default failure action is.
  Kdump service should fail irrespective of default action.

- Our default dump target is root disk and path /var/crash. If we detect
  some disk mounted on /var/crash we fail.

- We should do this checking *only* if user has not specified any disk
  and path in /etc/kdump.conf. If user has specified root disk in
  /etc/kdump.conf, then we should continue to dump.

- We need to give a very clear message to user that why dump is failing
  and  what user needs to do to avoid problem.

Thanks
Vivek
> Signed-off-by: Baoquan He
>
> kexec-kdump-howto.txt |  3 +++
>  mkdumprd              | 20 ++++++++++++++++++++
>  2 files changed, 23 insertions(+)
>
> diff --git a/kexec-kdump-howto.txt b/kexec-kdump-howto.txt
> index 7ffeab9..a43c225 100644
> --- a/kexec-kdump-howto.txt
> +++ b/kexec-kdump-howto.txt
> @@ -430,6 +430,9 @@ There are other default actions available though.
> poweroff
> Poweroff system after failure.
>
> +Note that if default action is set to dump_to_rootfs, kdump will fail
> +loading of kdump kernel when a different disk is mounted on 'save path'.
>
> Compression and filtering
>
> The 'core_collector' parameter in kdump.conf allows you to specify a custom
> diff --git a/mkdumprd b/mkdumprd
> index bc002bc..a86f8bb 100644
> --- a/mkdumprd
> +++ b/mkdumprd
> @@ -370,6 +370,24 @@ get_default_action_target()
>      return
>  }
>
> +check_default_action_target()
> +{
> local _target
> local _mntpoint
> local _action=$(grep "^default" /etc/kdump.conf 2>/dev/null | awk '{print $2}')
> if [ -n "$_action" ] && [ "$_action" = "dump_to_rootfs" ]; then
>    #get rootfs device name
>    mkdir -p $SAVE_PATH 
>    _mntpoint=`df $SAVE_PATH | tail -1 |  awk '{print $NF}'`
>    _target=`df $SAVE_PATH | tail -1 |  awk '{print $1}'`
>    if [ "$_mntpoint" != "/" ]; then
>        perror_exit "$_target is mounted on $_mntpoint"
>    fi
> fi
> return
>
> +}
>
> get_override_resettable()
>  {
>      local override_resettable
> @@ -453,6 +471,8 @@ check_resettable()
>      return 1
>  }
>
> +check_default_action_target
>
> if ! check_resettable; then
>      exit 1
>  fi
> -- 
> 1.8.3.1
>
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