kdump-lib: Skip adding reserved memory for small-memory machine

This increased "crashkernel=" raises the risk of OOM conditions in the
production kernel, particularly on small-memory machines that typically
lack such hardware features (Mellanox network cards, SMMU). So we
skip that case on aarch64. For other arches, the above factors are not
considered, so ignore them for the time being.

Signed-off-by: Pingfan Liu <[email protected]>

Author: Pingfan Liu

kdump-lib.sh

@@ -989,6 +989,7 @@ kdump_get_arch_recommend_crashkernel()
 {
 	local _arch _ck_cmdline _dump_mode
 	local _delta=0
+	local _skip=0
 
 	if [[ -z $1 ]]; then
 		if is_fadump_capable; then
@@ -1015,6 +1016,8 @@ kdump_get_arch_recommend_crashkernel()
 		else
 			_running_kernel=$2
 		fi
+		# skip adding additional memory for small-memory machine
+		_skip=1
 
 		# the naming convention of 64k variant suffixes with +64k, e.g. "vmlinuz-5.14.0-312.el9.aarch64+64k"
 		if echo "$_running_kernel" | grep -q 64k; then
@@ -1038,7 +1041,7 @@ kdump_get_arch_recommend_crashkernel()
 		fi
 	fi
 
-	echo -n "$(_crashkernel_add "$_ck_cmdline" "${_delta}M")"
+	echo -n "$(_crashkernel_add "$_ck_cmdline" "${_delta}M" "$_skip")"
 }
 
 # return recommended size based on current system RAM size