kernel fails allocating crashkernel memory when using the KASLR kernel feautre

i am using the 4.19.149 kernel on x86_64 platform running on centos6.2.my compile kernel configuration contains the following options:

CONFIG_PHYSICAL_START=0x1000000CONFIG_RELOCATABLE=yCONFIG_RANDOMIZE_BASE=y

my kernel command line is:

?> cat /proc/cmdlinero root=LABEL=/ rd_NO_LUKS  KEYBOARDTYPE=pc KEYTABLE=us LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=512M@0M nompath append="nmi_watchdog=2" printk.time=1 rd_NO_LVM rd_NO_DM dm_mod.use_blk_mq=y rcutree.kthread_prio=99 intel_pstate=enable intel_idle.max_cstate=0 processor.max_cstate=1 idle=halt console=tty0 console=ttyS0,38400n8d

so to summarize thing:

1. i am requesting the kernel to allocate 512M for crashkernel at the low memory region.when looking in the kernel arch/x86/kernel/setup.c:i can see that for my configuration the memory the kernel tries allocating those 512M ar between 16M-896M:

   #define CRASH_ALIGN     (16 << 20)...# define CRASH_ADDR_LOW_MAX (896UL << 20)...static void __init reserve_crashkernel(void)....    if (crash_base <= 0) {    /*     * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,     * as old kexec-tools loads bzImage below that, unless     * "crashkernel=size[KMG],high" is specified.     */    crash_base = memblock_find_in_range(CRASH_ALIGN,                        high ? CRASH_ADDR_HIGH_MAX                         : CRASH_ADDR_LOW_MAX,                        crash_size, CRASH_ALIGN);    if (!crash_base) {        pr_info("crashkernel reservation failed - No suitable area found.\n");        return;    }```

2. since i am using the CONFIG_RANDOMIZE_BASE option, on boot, before allocating the memory for thecrashkernel, the boot loader extract my kernel into randomize physical address.code at arch/x86/boot/compressed/kaslr.c

the problem is that once i a while, the randomize kernel address causes failure in allocating memory for the crashkernel.for example: on one of my reboots:

?> cat /proc/iomem00000000-00000fff : Reserved00001000-0009fbff : System RAM0009fc00-0009ffff : Reserved000a0000-000bffff : PCI Bus 0000:00000f0000-000fffff : Reserved  000f0000-000fffff : System ROM00100000-bfff9fff : System RAM  17000000-17c02fff : Kernel code  17c03000-183523ff : Kernel data  18883000-189fffff : Kernel bssbfffa000-bfffffff : Reservedc0000000-febfefff : PCI Bus 0000:00  febf7000-febf707f : 0000:00:03.0  febf8000-febf81ff : 0000:00:04.0  febf9000-febf91ff : 0000:00:05.0  febfa000-febfa1ff : 0000:00:06.0  febfb000-febfb1ff : 0000:00:07.0  febfc000-febfc1ff : 0000:00:08.0  febfd000-febfd1ff : 0000:00:09.0  febfe000-febfe03f : 0000:00:0a.0fec00000-fec003ff : IOAPIC 0fee00000-fee00fff : Local APICfffbc000-ffffffff : Reserved

in this example the kernel gets 368M-380M, which leaves no room for my 512M crashkernel memory (not from top to bottom - 896M-380M is not enough and not from bottom up 16M-368M is not enough).my questions are:

1. this seems like a bug in the KASLR feature - is this a known issue ?
2. is there a way to tell the KASLR to avoid randomizing the kernel address into the low memory region ? i can see that using the memmap command line parameter i can add memory regions which will achieve that, the problem is that those memmaps causes the allocation of the crashkernel to fail as well.thanks.