ppc64el kernel access of bad area (ext4_htree_store_dirent->rb_insert_color)

[Rafael David Tinoco]

It looks like the same stacktrace that was reported in this thread. This has
been reported to ppc64el AND we got a reproducer (ocfs2-tools autopkgtests).

[ 85.605850] Faulting instruction address: 0xc000000000e81168
[ 85.605901] Oops: Kernel access of bad area, sig: 11 [#1]
[ 85.605970] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
[ 85.606029] Modules linked in: ocfs2 quota_tree ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue iptable_mangle xt_TCPMSS xt_tcpudp bpfilter dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua vmx_crypto crct10dif_vpmsum sch_fq_codel ip_tables x_tables autofs4 btrfs xor zstd_compress raid6_pq libcrc32c crc32c_vpmsum virtio_net virtio_blk net_failover failover
[ 85.606291] CPU: 0 PID: 1 Comm: systemd Not tainted 5.3.0-18-generic #19-Ubuntu
[ 85.606350] NIP: c000000000e81168 LR: c00000000054f240 CTR: 0000000000000000
[ 85.606410] REGS: c00000005a3e3700 TRAP: 0300 Not tainted (5.3.0-18-generic)
[ 85.606469] MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 28024448 XER: 00000000
[ 85.606531] CFAR: 0000701f9806f638 DAR: 0000000001744098 DSISR: 40000000 IRQMASK: 0
[ 85.606531] GPR00: 0000000000007374 c00000005a3e3990 c0000000019c9100 c00000004fe462a8
[ 85.606531] GPR04: c00000005856d840 000000000000000e 0000000074656772 c00000004fe4a568
[ 85.606531] GPR08: 0000000000000000 c000000058568004 0000000001744090 0000000000000000
[ 85.606531] GPR12: 00000000e8086002 c000000001d60000 00007fffddd522d0 0000000000000000
[ 85.606531] GPR16: 0000000000000000 0000000000000000 0000000000000000 c00000000755e07c
[ 85.606531] GPR20: c0000000598caca8 c00000005a3e3a58 0000000000000000 c000000058292f00
[ 85.606531] GPR24: c000000000eea710 0000000000000000 c00000005856d840 c00000000755e074
[ 85.606531] GPR28: 000000006518907d c00000005a3e3a68 c00000004fe4b160 00000000027c47b6
[ 85.607079] NIP [c000000000e81168] rb_insert_color+0x18/0x1c0
[ 85.607137] LR [c00000000054f240] ext4_htree_store_dirent+0x140/0x1c0
[ 85.607186] Call Trace:
[ 85.607208] [c00000005a3e3990] [c00000000054f158] ext4_htree_store_dirent+0x58/0x1c0 (unreliable)
[ 85.607279] [c00000005a3e39e0] [c000000000594cd8] htree_dirblock_to_tree+0x1b8/0x380
[ 85.607340] [c00000005a3e3b00] [c0000000005962c0] ext4_htree_fill_tree+0xc0/0x3f0
[ 85.607401] [c00000005a3e3c00] [c00000000054ebe4] ext4_readdir+0x814/0xce0
[ 85.607459] [c00000005a3e3d40] [c000000000472d6c] iterate_dir+0x1fc/0x280
[ 85.607511] [c00000005a3e3d90] [c0000000004746f0] ksys_getdents64+0xa0/0x1f0
[ 85.607572] [c00000005a3e3e00] [c000000000474868] sys_getdents64+0x28/0x130
[ 85.607622] [c00000005a3e3e20] [c00000000000b388] system_call+0x5c/0x70
[ 85.607672] Instruction dump:
[ 85.607703] 4082ffe8 4e800020 38600000 4e800020 60000000 60000000 e9230000 2c290000
[ 85.607764] 4182018c e9490000 71480001 4c820020 <e90a0008> 7c284840 2fa80000 4182006c
[ 85.607827] ---[ end trace cfc53af0f8d62cef ]---
[ 85.610600]
[ 86.611522] BUG: Unable to handle kernel data access at 0xc000030058567eff
[ 86.611604] Faulting instruction address: 0xc000000000403aa8
[ 86.611656] Oops: Kernel access of bad area, sig: 11 [#2]
[ 86.611697] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
[ 86.611748] Modules linked in: ocfs2 quota_tr

Thread from beginning 2018, so I guess this issue is pretty intermittent but
might exist, and, perhaps, its related to specific arches/machines ?