RHELSA DP 7.1: aarch64 kernel seems to hang when booting with mem=16G, debugging shows kernel panic at unpack_to_rootfs

Issue

The aarch64 (ARM64) kernel gets stuck if you try to boot with mem=16G. The only output is:

EFI stub: Booting Linux Kernel...
EFI stub: Using DTB from configuration table
EFI stub: Exiting boot services and installing virtual address map...
L3c Cache: 8MB

If I add some debug options, "mem=16G earlycon=uart,mmio32,0x1c021000 keep_bootcon uefi_debug", then I get some more output showing a kernel panic at unpack_to_rootfs

[    7.303629] Unpacking initramfs... 
[    7.344307] Unable to handle kernel paging request at virtual address fffffe0f8980d000 
[    7.439053] pgd = fffffe0000ef0000 
[    7.479714] [fffffe0f8980d000] *pgd=0000000000000000, *pud=0000000000000000, *pmd=0000000000000000 
[    7.587144] Internal error: Oops: 96000006 [#1] SMP 
[    7.645486] Modules linked in: 
[    7.681888] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 3.19.0-0.79.aa7a.aarch64 #1 
[    7.771430] Hardware name: HP ProLiant m400 Server/ProLiant m400 Server, BIOS U02 05/01/2015 
[    7.872310] task: fffffe03e0000000 ti: fffffe03e0080000 task.ti: fffffe03e0080000 
[    7.961752] PC is at unpack_to_rootfs+0xc4/0x278 
[    8.016974] LR is at unpack_to_rootfs+0x6c/0x278 
[    8.072094] pc : [<fffffe0000b923b8>] lr : [<fffffe0000b92360>] pstate: 60000045 
[    8.160493] sp : fffffe03e0083d30 
[    8.200013] x29: fffffe03e0083d30 x28: 0000000000000000  
[    8.263453] x27: fffffe0000d40000 x26: 00000000000000db  
[    8.326893] x25: fffffe0000913f50 x24: fffffe0000d0a540  
[    8.390333] x23: fffffe0000d40078 x22: fffffe0000bd7000  
[    8.453773] x21: fffffe0000bd7230 x20: fffffe0f8980d000  
[    8.517213] x19: 0000000001b5168c x18: fffffe03f027ffff  
[    8.580653] x17: 000000000000001f x16: 0000000000000074  
[    8.644093] x15: ffffffffffffffff x14: 0720072007200720  
[    8.707533] x13: 0720072007200720 x12: 0720072007200720  
[    8.770973] x11: 0720072007200720 x10: 0720072007200720  
[    8.834413] x9 : 0000000000000000 x8 : 000000000000001a  
[    8.897853] x7 : 0000000000000019 x6 : fffffe03e03d4000  
[    8.961293] x5 : fffffe0000bc0ff8 x4 : fffffe0400305c80  
[    9.024733] x3 : fffffe0400305c80 x2 : fffffe0000bd7230  
[    9.088173] x1 : 0000000000000000 x0 : fffffe03e03d2000