[5.6.0-rc2-next-20200218/powerpc] Boot failure on POWER9

[Sachin Sant]

>> could you please test your boot with original patch from here:
>> 
>> https://patchwork.kernel.org/patch/11360007/
> 
> After you tried the above patch instead of the problem patch,
> do one more test and apply the below on current linux-next.
> Please, say which of the patches makes your kernel bootable again.
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 63bb6a2aab81..7b9b48dcbc60 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -334,7 +334,7 @@ static int memcg_expand_one_shrinker_map(struct mem_cgroup *memcg,
> 		if (!old)
> 			return 0;
> 
> -		new = kvmalloc_node(sizeof(*new) + size, GFP_KERNEL, nid);
> +		new = kmalloc_node(sizeof(*new) + size, GFP_KERNEL, nid);
> 		if (!new)
> 			return -ENOMEM;
> 
> @@ -378,7 +378,7 @@ static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg)
> 	mutex_lock(&memcg_shrinker_map_mutex);
> 	size = memcg_shrinker_map_size;
> 	for_each_node(nid) {
> -		map = kvzalloc_node(sizeof(*map) + size, GFP_KERNEL, nid);
> +		map = kzalloc_node(sizeof(*map) + size, GFP_KERNEL, nid);
> 		if (!map) {
> 			memcg_free_shrinker_maps(memcg);
> 			ret = -ENOMEM;

With this incremental patch applied on top of current linux-next, machine fails to boot

[    8.868433] BUG: Kernel NULL pointer dereference on read at 0x000073b0
[    8.868439] Faulting instruction address: 0xc0000000003d55f4
[    8.868444] Oops: Kernel access of bad area, sig: 11 [#1]
[    8.868449] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
[    8.868453] Modules linked in:
[    8.868458] CPU: 18 PID: 1 Comm: systemd Not tainted 5.6.0-rc2-next-20200218-autotest+ #4
[    8.868463] NIP:  c0000000003d55f4 LR: c0000000003d5b94 CTR: 0000000000000000
[    8.868468] REGS: c0000008b3783710 TRAP: 0300   Not tainted  (5.6.0-rc2-next-20200218-autotest+)
[    8.868474] MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 24004844  XER: 00000000
[    8.868481] CFAR: c00000000000dec4 DAR: 00000000000073b0 DSISR: 40000000 IRQMASK: 1 
[    8.868481] GPR00: c0000000003d5b94 c0000008b37839a0 c00000000155d400 c0000008b301f500 
[    8.868481] GPR04: 0000000000000dc0 0000000000000002 c0000000003fee38 c0000008bb298620 
[    8.868481] GPR08: 00000008ba1f0000 0000000000000001 0000000000000000 0000000000000000 
[    8.868481] GPR12: 0000000024004844 c00000001ec54200 0000000000000000 0000000000000000 
[    8.868481] GPR16: c0000008a1a60048 c000000001595898 c000000001750c18 0000000000000002 
[    8.868481] GPR20: c000000001750c28 c000000001624470 0000000fffffffe0 5deadbeef0000122 
[    8.868481] GPR24: 0000000000000001 0000000000000dc0 0000000000000002 c0000000003fee38 
[    8.868481] GPR28: c0000008b301f500 c0000008bb298620 0000000000000000 c00c000002286d00 
[    8.868529] NIP [c0000000003d55f4] ___slab_alloc+0x1f4/0x760
[    8.868534] LR [c0000000003d5b94] __slab_alloc+0x34/0x60
[    8.868538] Call Trace:
[    8.868541] [c0000008b37839a0] [c0000000003d5734] ___slab_alloc+0x334/0x760 (unreliable)
[    8.868547] [c0000008b3783a80] [c0000000003d5b94] __slab_alloc+0x34/0x60
[    8.868553] [c0000008b3783ab0] [c0000000003d6fa0] __kmalloc_node+0x110/0x490
[    8.868559] [c0000008b3783b30] [c0000000003fee38] mem_cgroup_css_online+0x108/0x270
[    8.868565] [c0000008b3783b90] [c000000000235aa8] online_css+0x48/0xd0
[    8.868571] [c0000008b3783bc0] [c00000000023eaec] cgroup_apply_control_enable+0x2ec/0x4d0
[    8.868577] [c0000008b3783ca0] [c000000000242318] cgroup_mkdir+0x228/0x5f0
[    8.868583] [c0000008b3783d10] [c00000000051e170] kernfs_iop_mkdir+0x90/0xf0
[    8.868589] [c0000008b3783d50] [c00000000043dc00] vfs_mkdir+0x110/0x230
[    8.868594] [c0000008b3783da0] [c000000000441c90] do_mkdirat+0xb0/0x1a0
[    8.868601] [c0000008b3783e20] [c00000000000b278] system_call+0x5c/0x68
[    8.868605] Instruction dump:
[    8.868608] 7c421378 e95f0000 714a0001 4082fff0 4bffff64 60000000 60000000 faa10088 
[    8.868615] 3ea2000c 3ab57070 7b4a1f24 7d55502a <e94a73b0> 2faa0000 409e0394 3d02002a 
[    8.868623] ---[ end trace f9b8e3c36493f430 ]---
[    8.870690] 
[    9.870701] Kernel panic - not syncing: Fatal exception

Thanks
-Sachin