Re: [PATCH v4] kdump-lib: use non-debug kernels first

Kdump uses currently running kernel as default, but when currently running kernel is a debug kernel, it will consume more memory, which may cause out-of-memory and fail to collect vmcore. Now we will try to use non-debug kernels first if possible. Also extract the logic of determine KDUMP_KERNEL from prepare_kdump_bootinfo into a function. This function will return KDUMP_KERNEL given a kernel version. Signed-off-by: Lichen Liu <lichliu(a)redhat.com&gt; --- Update: v1 -> v2: - extract the logic of determine KDUMP_KERNEL from prepare_kdump_bootinfo into a function. v2 -> v3: - remove an extra space. - remove 2 unused variable declarations. - warn when using debug kernel. v3 -> v4: - remove useless double quotes. - add declarations of two temporary variables. kdump-lib.sh | 67 ++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 49 insertions(+), 18 deletions(-) diff --git a/kdump-lib.sh b/kdump-lib.sh index b137c89..944d823 100755 --- a/kdump-lib.sh +++ b/kdump-lib.sh @@ -633,46 +633,77 @@ prepare_kexec_args() echo "$kexec_args" } -# -# Detect initrd and kernel location, results are stored in global enviromental variables: -# KDUMP_BOOTDIR, KDUMP_KERNELVER, KDUMP_KERNEL, DEFAULT_INITRD, and KDUMP_INITRD -# -# Expectes KDUMP_BOOTDIR, KDUMP_IMG, KDUMP_IMG_EXT, KDUMP_KERNELVER to be loaded from config already -# and will prefer already set values so user can specify custom kernel/initramfs location -# -prepare_kdump_bootinfo() +# prepare_kdump_kernel <kdump_kernelver> +# This function return kdump_kernel given a kernel version. +prepare_kdump_kernel() { - local boot_img boot_imglist boot_dirlist boot_initrdlist - local machine_id dir img default_initrd_base var_target_initrd_dir - - if [[ -z $KDUMP_KERNELVER ]]; then - KDUMP_KERNELVER="$(uname -r)" - fi - + local kdump_kernelver=$1 + local dir img boot_dirlist boot_imglist kdump_kernel machine_id read -r machine_id < /etc/machine-id + boot_dirlist=${KDUMP_BOOTDIR:-"/boot /boot/efi /efi /"} - boot_imglist="$KDUMP_IMG-$KDUMP_KERNELVER$KDUMP_IMG_EXT $machine_id/$KDUMP_KERNELVER/$KDUMP_IMG" + boot_imglist="$KDUMP_IMG-$kdump_kernelver$KDUMP_IMG_EXT $machine_id/$kdump_kernelver/$KDUMP_IMG" # Use BOOT_IMAGE as reference if possible, strip the GRUB root device prefix in (hd0,gpt1) format boot_img="$(sed "s/^BOOT_IMAGE=\((\S*)\)\?\(\S*\) .*/\2/" /proc/cmdline)" - if [[ -n $boot_img ]]; then + if [[ "$boot_img" == *"$kdump_kernelver" ]]; then boot_imglist="$boot_img $boot_imglist" fi for dir in $boot_dirlist; do for img in $boot_imglist; do if [[ -f "$dir/$img" ]]; then - KDUMP_KERNEL=$(echo "$dir/$img" | tr -s '/') + kdump_kernel=$(echo "$dir/$img" | tr -s '/') break 2 fi done done + echo "$kdump_kernel" +} + +# +# Detect initrd and kernel location, results are stored in global environmental variables: +# KDUMP_BOOTDIR, KDUMP_KERNELVER, KDUMP_KERNEL, DEFAULT_INITRD, and KDUMP_INITRD +# +# Expectes KDUMP_BOOTDIR, KDUMP_IMG, KDUMP_IMG_EXT, KDUMP_KERNELVER to be loaded from config already +# and will prefer already set values so user can specify custom kernel/initramfs location +# +prepare_kdump_bootinfo() +{ + local boot_initrdlist nondebug_kernelver debug_kernelver + local default_initrd_base var_target_initrd_dir + + if [[ -z $KDUMP_KERNELVER ]]; then + KDUMP_KERNELVER=$(uname -r) + nondebug_kernelver=$(sed -n -e 's/\(.*\)+debug$/\1/p' <<< "$KDUMP_KERNELVER") + fi + + # Use nondebug kernel if possible, because debug kernel will consume more memory and may oom. + if [[ -n $nondebug_kernelver ]]; then + dinfo "Trying to use $nondebug_kernelver." + debug_kernelver=$KDUMP_KERNELVER + KDUMP_KERNELVER=$nondebug_kernelver + fi + + KDUMP_KERNEL=$(prepare_kdump_kernel "$KDUMP_KERNELVER") + + if ! [[ -e $KDUMP_KERNEL ]]; then + if [[ -n $debug_kernelver ]]; then + dinfo "Fallback to using debug kernel" + KDUMP_KERNELVER=$debug_kernelver + KDUMP_KERNEL=$(prepare_kdump_kernel "$KDUMP_KERNELVER") + fi + fi if ! [[ -e $KDUMP_KERNEL ]]; then derror "Failed to detect kdump kernel location" return 1 fi + if [[ "$KDUMP_KERNEL" == *"+debug" ]]; then + dwarn "Using debug kernel, you may need to set a larger crashkernel than the default value." + fi + # Set KDUMP_BOOTDIR to where kernel image is stored KDUMP_BOOTDIR=$(dirname "$KDUMP_KERNEL") -- 2.31.1