I can reproduce this with 5.4.0-105.119 + stress-ng 48be8ff (V0.13.11)... Not sure what's going on here. It looks like this was failed after the sigabrt test: Apr 22 09:04:48 kernel04 stress-ng: info: [154111] dispatching hogs: 4 shm-sysv Apr 22 09:04:51 kernel04 stress-ng: info: [154111] successful run completed in 2.71s Apr 22 09:04:51 kernel04 stress-ng: invoked with './stress-ng -v -t 5 --sigabrt 4 --sigabrt-ops 3000 --ignite-cpu --syslog --verbose --verify --oomable' by user 0 'root' Apr 22 09:04:51 kernel04 stress-ng: system: 'kernel04' Linux 5.4.0-105-generic #119-Ubuntu SMP Mon Mar 7 18:48:48 UTC 2022 s390x Apr 22 09:04:51 kernel04 stress-ng: memory (MB): total 3803.07, free 3044.49, shared 0.52, buffer 70.57, swap 2241.13, free swap 2174.96 Apr 22 09:04:51 kernel04 stress-ng: info: [155627] setting to a 5 second run per stressor Apr 22 09:04:51 kernel04 stress-ng: info: [155627] dispatching hogs: 4 sigabrt Apr 22 09:04:58 kernel04 stress-ng: info: [155627] successful run completed in 7.73s Apr 22 09:05:31 kernel04 kernel: [ 2447.055320] ------------[ cut here ]------------ Apr 22 09:05:31 kernel04 kernel: [ 2447.055324] kernel BUG at mm/zswap.c:896! Apr 22 09:05:31 kernel04 kernel: [ 2447.055375] illegal operation: 0001 ilc:1 [#1] SMP Apr 22 09:05:31 kernel04 kernel: [ 2447.055379] Modules linked in: sctp vhost_net tap vhost_vsock vmw_vsock_virtio_transport_common vhost vsock zfs(PO) zunicode(PO) zlua(PO) zcommon(PO) znvpair(PO) zavl(PO) icp(PO) spl(O) dccp_ipv4 dccp tgr192 streebog_generic sm3_generic sha3_generic rmd320 rmd256 rmd160 rmd128 nhpoly1305 poly1305_generic michael_mic md4 cmac ccm algif_rng twofish_generic twofish_common tea sm4_generic serpent_generic seed khazad fcrypt des_generic cast6_generic cast5_generic cast_common camellia_generic blowfish_generic blowfish_common anubis algif_skcipher algif_hash aegis128 algif_aead af_alg nf_conntrack_netlink xfrm_user xfrm_algo xt_addrtype br_netfilter overlay xt_conntrack ipt_REJECT nf_reject_ipv4 ip6table_mangle ip6table_nat nf_tables nfnetlink aufs ip6table_filter ip6_tables iptable_mangle xt_CHECKSUM iptable_nat xt_MASQUERADE xt_tcpudp bridge stp llc iptable_filter bpfilter openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 binfmt_misc dm_multipath scsi_dh_rdac Apr 22 09:05:31 kernel04 kernel: [ 2447.055441] scsi_dh_emc scsi_dh_alua vmur vfio_ccw vfio_mdev mdev vfio_iommu_type1 vfio sch_fq_codel nfsd auth_rpcgss drm nfs_acl lockd drm_panel_orientation_quirks i2c_core grace sunrpc ip_tables x_tables btrfs zstd_compress zlib_deflate raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 linear pkey zcrypt crc32_vx_s390 ghash_s390 prng aes_s390 des_s390 libdes sha512_s390 sha256_s390 dasd_eckd_mod qeth_l2 sha1_s390 sha_common qeth qdio dasd_mod ccwgroup Apr 22 09:05:31 kernel04 kernel: [ 2447.055499] CPU: 4 PID: 155935 Comm: apport Tainted: P O 5.4.0-105-generic #119-Ubuntu Apr 22 09:05:31 kernel04 kernel: [ 2447.055501] Hardware name: IBM 2964 N63 400 (z/VM 6.4.0) Apr 22 09:05:31 kernel04 kernel: [ 2447.055503] Krnl PSW : 0704c00180000000 00000000423aabca (zswap_writeback_entry+0x32a/0x340) Apr 22 09:05:31 kernel04 kernel: [ 2447.055513] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 Apr 22 09:05:31 kernel04 kernel: [ 2447.055515] Krnl GPRS: 0000000000000000 000000006c079100 ffffffffffffffea 0000000000001000 Apr 22 09:05:31 kernel04 kernel: [ 2447.055517] 0000000084b95000 0000000084b96000 000003e0ffffffea 00000000f1bfde28 Apr 22 09:05:31 kernel04 kernel: [ 2447.055518] 000003d08212e540 00000000f1bfde20 0000000000037f46 000000002522d2d8 Apr 22 09:05:31 kernel04 kernel: [ 2447.055520] 000000006c079100 000000009d485ac0 00000000423aaa88 000003e00f5f70a8 Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] Krnl Code: 00000000423aabbc: c0e50032bb1a brasl %r14,0000000042a021f0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] 00000000423aabc2: a7f4ffaa brc 15,00000000423aab16 Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] #00000000423aabc6: a7f40001 brc 15,00000000423aabc8 Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] >00000000423aabca: ec81ffff00d9 aghik %r8,%r1,-1 Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] 00000000423aabd0: a7f4fefe brc 15,00000000423aa9cc Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] 00000000423aabd4: 0707 bcr 0,%r7 Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] 00000000423aabd6: 0707 bcr 0,%r7 Apr 22 09:05:31 kernel04 kernel: [ 2447.055529] 00000000423aabd8: 0707 bcr 0,%r7 Apr 22 09:05:31 kernel04 kernel: [ 2447.055545] Call Trace: Apr 22 09:05:31 kernel04 kernel: [ 2447.055548] ([<00000000423aaa88>] zswap_writeback_entry+0x1e8/0x340) Apr 22 09:05:31 kernel04 kernel: [ 2447.055552] [<00000000423ea23c>] zbud_reclaim_page+0x14c/0x2b0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055554] [<00000000423ea3e0>] zbud_zpool_shrink+0x40/0x80 Apr 22 09:05:31 kernel04 kernel: [ 2447.055643] [<00000000423aae72>] zswap_frontswap_store+0x292/0x5c0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055645] [<00000000423a91a4>] __frontswap_store+0xb4/0x1a0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055649] [<00000000423a05ba>] swap_writepage+0x5a/0xc0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055654] [<0000000042346908>] pageout.isra.0+0x118/0x3e0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055657] [<000000004234a9fc>] shrink_page_list+0xa3c/0xe90 Apr 22 09:05:31 kernel04 kernel: [ 2447.055660] [<000000004234ba50>] shrink_inactive_list+0x1f0/0x4e0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055662] [<000000004234c644>] shrink_node_memcg+0x2f4/0x3f0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055665] [<000000004234c804>] shrink_node+0xc4/0x4d0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055668] [<000000004234ccee>] do_try_to_free_pages+0xde/0x400 Apr 22 09:05:31 kernel04 kernel: [ 2447.055673] [<000000004234d0fe>] try_to_free_pages+0xee/0x230 Apr 22 09:05:31 kernel04 kernel: [ 2447.055675] [<0000000042399c8c>] __alloc_pages_slowpath+0x31c/0xe90 Apr 22 09:05:31 kernel04 kernel: [ 2447.055677] [<000000004239aab4>] __alloc_pages_nodemask+0x2b4/0x330 Apr 22 09:05:31 kernel04 kernel: [ 2447.055681] [<00000000423b6b2a>] alloc_pages_vma+0x9a/0x280 Apr 22 09:05:31 kernel04 kernel: [ 2447.055684] [<00000000423a17e4>] __read_swap_cache_async+0x194/0x270 Apr 22 09:05:31 kernel04 kernel: [ 2447.055686] [<00000000423a18ea>] read_swap_cache_async+0x2a/0x60 Apr 22 09:05:31 kernel04 kernel: [ 2447.055688] [<00000000423a1b4a>] swap_cluster_readahead+0x22a/0x2e0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055691] [<00000000423a202e>] swapin_readahead+0x2ce/0x410 Apr 22 09:05:31 kernel04 kernel: [ 2447.055696] [<00000000423762a4>] do_swap_page+0x1f4/0x880 Apr 22 09:05:31 kernel04 kernel: [ 2447.055698] [<000000004237809e>] __handle_mm_fault+0x7ee/0x910 Apr 22 09:05:31 kernel04 kernel: [ 2447.055700] [<0000000042378286>] handle_mm_fault+0xc6/0x180 Apr 22 09:05:31 kernel04 kernel: [ 2447.055704] [<0000000042151770>] do_dat_exception+0x120/0x3d0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055710] [<0000000042a14e9e>] pgm_check_handler+0x1da/0x230 Apr 22 09:05:31 kernel04 kernel: [ 2447.055711] Last Breaking-Event-Address: Apr 22 09:05:31 kernel04 kernel: [ 2447.055713] [<00000000423aabc6>] zswap_writeback_entry+0x326/0x340 Apr 22 09:05:31 kernel04 kernel: [ 2447.055716] ---[ end trace 79ec165717f6252b ]--- Apr 22 09:05:31 kernel04 kernel: [ 2447.055721] ------------[ cut here ]------------ Apr 22 09:05:31 kernel04 kernel: [ 2447.055725] WARNING: CPU: 4 PID: 155935 at kernel/exit.c:726 do_exit+0x40/0xb60 Apr 22 09:05:31 kernel04 kernel: [ 2447.055727] Modules linked in: sctp vhost_net tap vhost_vsock vmw_vsock_virtio_transport_common vhost vsock zfs(PO) zunicode(PO) zlua(PO) zcommon(PO) znvpair(PO) zavl(PO) icp(PO) spl(O) dccp_ipv4 dccp tgr192 streebog_generic sm3_generic sha3_generic rmd320 rmd256 rmd160 rmd128 nhpoly1305 poly1305_generic michael_mic md4 cmac ccm algif_rng twofish_generic twofish_common tea sm4_generic serpent_generic seed khazad fcrypt des_generic cast6_generic cast5_generic cast_common camellia_generic blowfish_generic blowfish_common anubis algif_skcipher algif_hash aegis128 algif_aead af_alg nf_conntrack_netlink xfrm_user xfrm_algo xt_addrtype br_netfilter overlay xt_conntrack ipt_REJECT nf_reject_ipv4 ip6table_mangle ip6table_nat nf_tables nfnetlink aufs ip6table_filter ip6_tables iptable_mangle xt_CHECKSUM iptable_nat xt_MASQUERADE xt_tcpudp bridge stp llc iptable_filter bpfilter openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 binfmt_misc dm_multipath scsi_dh_rdac Apr 22 09:05:31 kernel04 kernel: [ 2447.055756] scsi_dh_emc scsi_dh_alua vmur vfio_ccw vfio_mdev mdev vfio_iommu_type1 vfio sch_fq_codel nfsd auth_rpcgss drm nfs_acl lockd drm_panel_orientation_quirks i2c_core grace sunrpc ip_tables x_tables btrfs zstd_compress zlib_deflate raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 linear pkey zcrypt crc32_vx_s390 ghash_s390 prng aes_s390 des_s390 libdes sha512_s390 sha256_s390 dasd_eckd_mod qeth_l2 sha1_s390 sha_common qeth qdio dasd_mod ccwgroup Apr 22 09:05:31 kernel04 kernel: [ 2447.055778] CPU: 4 PID: 155935 Comm: apport Tainted: P D O 5.4.0-105-generic #119-Ubuntu Apr 22 09:05:31 kernel04 kernel: [ 2447.055780] Hardware name: IBM 2964 N63 400 (z/VM 6.4.0) Apr 22 09:05:31 kernel04 kernel: [ 2447.055781] Krnl PSW : 0704e00180000000 00000000421acaa0 (do_exit+0x40/0xb60) Apr 22 09:05:31 kernel04 kernel: [ 2447.055785] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 Apr 22 09:05:31 kernel04 kernel: [ 2447.055787] Krnl GPRS: 000000000000000a 000003e00f5f7698 00000000e62bdd48 0000000000000007 Apr 22 09:05:31 kernel04 kernel: [ 2447.055788] 0000000000000007 0000000042fde098 0000000000000001 000000000000000b Apr 22 09:05:31 kernel04 kernel: [ 2447.055790] 0704c00180000000 000000004212d200 0000000042ba4bf8 000000006c079100 Apr 22 09:05:31 kernel04 kernel: [ 2447.055792] 000000006c079100 0000000000000000 000003e00f5f6e78 000003e00f5f6e08 Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] Krnl Code: 00000000421aca90: e32010000004 lg %r2,0(%r1) Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] 00000000421aca96: ec1203598064 cgrj %r1,%r2,8,00000000421ad148 Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] #00000000421aca9c: a7f40001 brc 15,00000000421aca9e Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] >00000000421acaa0: 588003a8 l %r8,936 Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] 00000000421acaa4: ecd82bb70055 risbg %r13,%r8,43,183,0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] 00000000421acaaa: a774055b brc 7,00000000421ad560 Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] 00000000421acaae: e310b6b00012 lt %r1,1712(%r11) Apr 22 09:05:31 kernel04 kernel: [ 2447.055797] 00000000421acab4: a7840550 brc 8,00000000421ad554 Apr 22 09:05:31 kernel04 kernel: [ 2447.055815] Call Trace: Apr 22 09:05:31 kernel04 kernel: [ 2447.055818] ([<79ec165717f6252b>] 0x79ec165717f6252b) Apr 22 09:05:31 kernel04 kernel: [ 2447.055823] [<00000000421403ea>] die+0x14a/0x170 Apr 22 09:05:31 kernel04 kernel: [ 2447.055825] [<000000004212d340>] illegal_op+0x140/0x150 Apr 22 09:05:31 kernel04 kernel: [ 2447.055827] [<0000000042a14e9e>] pgm_check_handler+0x1da/0x230 Apr 22 09:05:31 kernel04 kernel: [ 2447.055829] [<00000000423aabca>] zswap_writeback_entry+0x32a/0x340 Apr 22 09:05:31 kernel04 kernel: [ 2447.055831] ([<00000000423aaa88>] zswap_writeback_entry+0x1e8/0x340) Apr 22 09:05:31 kernel04 kernel: [ 2447.055833] [<00000000423ea23c>] zbud_reclaim_page+0x14c/0x2b0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055835] [<00000000423ea3e0>] zbud_zpool_shrink+0x40/0x80 Apr 22 09:05:31 kernel04 kernel: [ 2447.055837] [<00000000423aae72>] zswap_frontswap_store+0x292/0x5c0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055839] [<00000000423a91a4>] __frontswap_store+0xb4/0x1a0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055841] [<00000000423a05ba>] swap_writepage+0x5a/0xc0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055843] [<0000000042346908>] pageout.isra.0+0x118/0x3e0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055845] [<000000004234a9fc>] shrink_page_list+0xa3c/0xe90 Apr 22 09:05:31 kernel04 kernel: [ 2447.055867] [<000000004234ba50>] shrink_inactive_list+0x1f0/0x4e0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055870] [<000000004234c644>] shrink_node_memcg+0x2f4/0x3f0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055872] [<000000004234c804>] shrink_node+0xc4/0x4d0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055874] [<000000004234ccee>] do_try_to_free_pages+0xde/0x400 Apr 22 09:05:31 kernel04 kernel: [ 2447.055876] [<000000004234d0fe>] try_to_free_pages+0xee/0x230 Apr 22 09:05:31 kernel04 kernel: [ 2447.055878] [<0000000042399c8c>] __alloc_pages_slowpath+0x31c/0xe90 Apr 22 09:05:31 kernel04 kernel: [ 2447.055880] [<000000004239aab4>] __alloc_pages_nodemask+0x2b4/0x330 Apr 22 09:05:31 kernel04 kernel: [ 2447.055882] [<00000000423b6b2a>] alloc_pages_vma+0x9a/0x280 Apr 22 09:05:31 kernel04 kernel: [ 2447.055884] [<00000000423a17e4>] __read_swap_cache_async+0x194/0x270 Apr 22 09:05:31 kernel04 kernel: [ 2447.055886] [<00000000423a18ea>] read_swap_cache_async+0x2a/0x60 Apr 22 09:05:31 kernel04 kernel: [ 2447.055888] [<00000000423a1b4a>] swap_cluster_readahead+0x22a/0x2e0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055890] [<00000000423a202e>] swapin_readahead+0x2ce/0x410 Apr 22 09:05:31 kernel04 kernel: [ 2447.055893] [<00000000423762a4>] do_swap_page+0x1f4/0x880 Apr 22 09:05:31 kernel04 kernel: [ 2447.055895] [<000000004237809e>] __handle_mm_fault+0x7ee/0x910 Apr 22 09:05:31 kernel04 kernel: [ 2447.055897] [<0000000042378286>] handle_mm_fault+0xc6/0x180 Apr 22 09:05:31 kernel04 kernel: [ 2447.055899] [<0000000042151770>] do_dat_exception+0x120/0x3d0 Apr 22 09:05:31 kernel04 kernel: [ 2447.055901] [<0000000042a14e9e>] pgm_check_handler+0x1da/0x230 Apr 22 09:05:31 kernel04 kernel: [ 2447.055902] Last Breaking-Event-Address: Apr 22 09:05:31 kernel04 kernel: [ 2447.055904] [<00000000421aca9c>] do_exit+0x3c/0xb60 Apr 22 09:05:31 kernel04 kernel: [ 2447.055905] ---[ end trace 79ec165717f6252c ]--- Apr 22 09:05:44 kernel04 CRON[156185]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1) Apr 22 09:05:44 kernel04 stress-ng: invoked with './stress-ng -v -t 5 --sigchld 4 --sigchld-ops 3000 --ignite-cpu --syslog --verbose --verify --oomable' by user 0 'root' Apr 22 09:05:45 kernel04 stress-ng: system: 'kernel04' Linux 5.4.0-105-generic #119-Ubuntu SMP Mon Mar 7 18:48:48 UTC 2022 s390x Apr 22 09:05:45 kernel04 stress-ng: memory (MB): total 3803.07, free 56.80, shared 0.09, buffer 4.61, swap 2241.13, free swap 336.73 Apr 22 09:05:45 kernel04 stress-ng: info: [156182] setting to a 5 second run per stressor Apr 22 09:05:45 kernel04 stress-ng: info: [156182] dispatching hogs: 4 sigchld Apr 22 09:05:45 kernel04 stress-ng: info: [156182] successful run completed in 0.82s