Greeting's Kernel Oops is seen on 4.17.0-rc7-next-20180601 kernel on a bare-metal machine when running lvm snapshot tests on nvme disks. Machine Type: Power 8 bare-metal kernel : 4.17.0-rc7-next-20180601 test: $ pvcreate -y /dev/nvme0n1 $ vgcreate avocado_vg /dev/nvme0n1 $ lvcreate --size 1.4T --name avocado_lv avocado_vg -y $ mkfs.ext2 /dev/avocado_vg/avocado_lv $ lvcreate --size 1G --snapshot --name avocado_sn /dev/avocado_vg/avocado_lv -y $ lvconvert --merge /dev/avocado_vg/avocado_sn the last command results in Oops: Unable to handle kernel paging request for data at address 0x000000d0 Faulting instruction address: 0xc0000000002dced4 Oops: Kernel access of bad area, sig: 11 [#1] LE SMP NR_CPUS=2048 NUMA PowerNV Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: dm_snapshot dm_bufio nvme bnx2x iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp tun bridge stp llc iptable_filter dm_mirror dm_region_hash dm_log dm_service_time vmx_crypto powernv_rng rng_core dm_multipath kvm_hv binfmt_misc kvm nfsd ip_tables x_tables autofs4 xfs lpfc crc_t10dif crct10dif_generic mdio nvme_fc libcrc32c nvme_fabrics nvme_core crct10dif_common [last unloaded: nvme] CPU: 70 PID: 157763 Comm: lvconvert Not tainted 4.17.0-rc7-next-20180601-autotest-autotest #1 NIP: c0000000002dced4 LR: c000000000244d14 CTR: c000000000244cf0 REGS: c000001f81d6b5a0 TRAP: 0300 Not tainted (4.17.0-rc7-next-20180601-autotest-autotest) MSR: 900000010280b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 22442444 XER: 20000000 CFAR: c000000000008934 DAR: 00000000000000d0 DSISR: 40000000 SOFTE: 0 GPR00: c000000000244d14 c000001f81d6b820 c00000000109c400 c000003c9d080180 GPR04: 0000000000000001 c000001fad510000 c000001fad510000 0000000000000001 GPR08: 0000000000000000 f000000000000000 f000000000000008 0000000000000000 GPR12: c000000000244cf0 c000001ffffc4f80 00007fffa0e31090 00007fffd9d9b470 GPR16: 0000000000000000 000000000000005c 00007fffa0e3a5b0 00007fffa0e62040 GPR20: 0000010014ad7d50 0000010014ad7d20 00007fffa0e64210 0000000000000001 GPR24: 0000000000000000 c00000000081bae0 c000001ed2461b00 d00000000f859d08 GPR28: c000003c9d080180 c000000000244d14 0000000000000001 0000000000000000 NIP [c0000000002dced4] kmem_cache_free+0x1a4/0x2b0 LR [c000000000244d14] mempool_free_slab+0x24/0x40 Call Trace: [c000001f81d6b820] [c0000000002dcfbc] kmem_cache_free+0x28c/0x2b0 (unreliable) [c000001f81d6b8b0] [c000000000244d14] mempool_free_slab+0x24/0x40 [c000001f81d6b8d0] [c000000000244e10] mempool_exit+0x50/0x90 [c000001f81d6b900] [c00000000081d730] dm_io_client_destroy+0x20/0x50 [c000001f81d6b930] [c00000000081f1dc] dm_kcopyd_client_destroy+0x9c/0x140 [c000001f81d6b9a0] [d00000000f851da4] dm_exception_table_exit.isra.14+0x204/0xaa0 [dm_snapshot] [c000001f81d6ba40] [c0000000008162d0] dm_table_destroy+0xa0/0x190 [c000001f81d6bad0] [c00000000081bc24] dev_suspend+0x144/0x330 [c000001f81d6bb10] [c00000000081c870] ctl_ioctl+0x350/0x4e0 [c000001f81d6bd00] [c00000000081ca18] dm_ctl_ioctl+0x18/0x30 [c000001f81d6bd20] [c000000000329b38] do_vfs_ioctl+0xc8/0x8b0 [c000001f81d6bdc0] [c00000000032a37c] ksys_ioctl+0x5c/0xe0 [c000001f81d6be10] [c00000000032a420] sys_ioctl+0x20/0x80 [c000001f81d6be30] [c00000000000b9e0] system_call+0x58/0x6c Instruction dump: 39295e50 7bca8502 794a3664 e9290000 7d495214 7d495378 e94a0008 794807e1 40c2010c ebe90018 7fbcf840 419e00f8 <e93f00d0> 7fbc4800 419efe9c e8bc0058 ---[ end trace d60580773711c361 ]--- essage from syslogd@localhost at Jun 4 08:34:20 ... kernel:Dumping ftrace buffer: [cache_from_obj: Wrong slab cache. ksm_rmap_item but object is from kmalloc-128 [WARNING: CPU: 0 PID: 157807 at mm/slab.h:381 kmem_cache_free+0x1d0/0x2b0 [Modules linked in: dm_snapshot dm_bufio nvme bnx2x iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp tun bridge stp llc iptable_filter dm_mirror dm_region_hash dm_log dm_service_time vmx_crypto powernv_rng rng_core dm_multipath kvm_hv binfmt_misc kvm nfsd ip_tables x_tables autofs4 xfs lpfc crc_t10dif crct10dif_generic mdio nvme_fc libcrc32c nvme_fabrics nvme_core crct10dif_common [last unloaded: nvme] [CPU: 0 PID: 157807 Comm: vgremove Tainted: G D 4.17.0-rc7-next-20180601-autotest-autotest #1 [NIP: c0000000002dcf00 LR: c0000000002dcefc CTR: 0000000000000000 [REGS: c000001ee130f500 TRAP: 0700 Tainted: G D (4.17.0-rc7-next-20180601-autotest-autotest) [MSR: 900000010282b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 22442422 XER: 20000000 [CFAR: c0000000001668f4 SOFTE: 0 [GPR00: c0000000002dcefc c000001ee130f780 c00000000109c400 000000000000004e [GPR04: c000001ff5c0cdd0 c000001ff5c23a70 0000000000000001 ffffffffffffffff [GPR08: 0000000000000000 c000001ff5c13880 0000001ff4e90000 9000000102803003 [GPR12: 0000000000002200 c000000001260000 00007fff7f2e1090 00007fffecda3550 [GPR16: 0000000000000000 000000000000005c 00007fff7f2ea5b0 00007fff7f312040 [GPR20: 0000010022679490 0000010022679460 00007fff7f314210 0000000000000003 [GPR24: 0000000000000000 c00000000081be10 c000001fad301500 d00000000f859d08 [GPR28: c000003c9d080180 c000000000244d14 c000001f63723908 c000001ff401f480 [NIP [c0000000002dcf00] kmem_cache_free+0x1d0/0x2b0 [LR [c0000000002dcefc] kmem_cache_free+0x1cc/0x2b0 [Call Trace: [[c000001ee130f780] [c0000000002dcefc] kmem_cache_free+0x1cc/0x2b0 (unreliable) [[c000001ee130f810] [c000000000244d14] mempool_free_slab+0x24/0x40 [[c000001ee130f830] [c000000000244e10] mempool_exit+0x50/0x90 [[c000001ee130f860] [c00000000081d730] dm_io_client_destroy+0x20/0x50 [[c000001ee130f890] [c00000000081f1dc] dm_kcopyd_client_destroy+0x9c/0x140 [[c000001ee130f900] [d00000000f851da4] dm_exception_table_exit.isra.14+0x204/0xaa0 [dm_snapshot] [[c000001ee130f9a0] [c0000000008162d0] dm_table_destroy+0xa0/0x190 [[c000001ee130fa30] [c0000000008118e8] __dm_destroy+0x198/0x230 [[c000001ee130fac0] [c00000000081bf64] dev_remove+0x154/0x1d0 [[c000001ee130fb10] [c00000000081c870] ctl_ioctl+0x350/0x4e0 [[c000001ee130fd00] [c00000000081ca18] dm_ctl_ioctl+0x18/0x30 [[c000001ee130fd20] [c000000000329b38] do_vfs_ioctl+0xc8/0x8b0 [[c000001ee130fdc0] [c00000000032a37c] ksys_ioctl+0x5c/0xe0 [[c000001ee130fe10] [c00000000032a420] sys_ioctl+0x20/0x80 [[c000001ee130fe30] [c00000000000b9e0] system_call+0x58/0x6c [419e00f8 e93f00d0 7fbc4800 419efe9c e8bc0058 e8df0058 3c62ffb5 3c82ff99 [3863f0a8 38846d18 4be899bd 60000000 <0fe00000> 7f9fe378 4bfffe70 60420000 [---[ end trace d60580773711c362 ]--- [cache_from_obj: Wrong slab cache. ksm_rmap_item but object is from kmalloc-128 -- Regard's Abdul Haleem IBM Linux Technology Centre