It is not always reproducible so far, but it start to show up on today’s linux-next. Look Trough the commits and noticed this recent one matched the new call traces, ac58e4fb03f9 (“ext4: move ext4 bmap to use iomap infrastructure") Thought? [ 206.744625][T13224] LTP: starting fallocate04 [ 207.601583][T27684] /dev/zero: Can't open blockdev [ 208.674301][T27684] EXT4-fs (loop0): mounting ext3 file system using the ext4 subsystem [ 208.680347][T27684] BUG: Unable to handle kernel instruction fetch (NULL pointer?) [ 208.680383][T27684] Faulting instruction address: 0x00000000 [ 208.680406][T27684] Oops: Kernel access of bad area, sig: 11 [#1] [ 208.680439][T27684] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV [ 208.680474][T27684] Modules linked in: ext4 crc16 mbcache jbd2 loop kvm_hv kvm ip_tables x_tables xfs sd_mod bnx2x ahci libahci mdio tg3 libata libphy firmware_class dm_mirror dm_region_hash dm_log dm_mod [ 208.680576][T27684] CPU: 117 PID: 27684 Comm: fallocate04 Tainted: G W 5.6.0-next-20200401+ #288 [ 208.680614][T27684] NIP: 0000000000000000 LR: c0080000102c0048 CTR: 0000000000000000 [ 208.680657][T27684] REGS: c000200361def420 TRAP: 0400 Tainted: G W (5.6.0-next-20200401+) [ 208.680700][T27684] MSR: 900000004280b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 42022228 XER: 20040000 [ 208.680760][T27684] CFAR: c00800001032c494 IRQMASK: 0 [ 208.680760][T27684] GPR00: c0000000005ac3f8 c000200361def6b0 c00000000165c200 c00020107dae0bd0 [ 208.680760][T27684] GPR04: 0000000000000000 0000000000000400 0000000000000000 0000000000000000 [ 208.680760][T27684] GPR08: c000200361def6e8 c0080000102c0040 000000007fffffff c000000001614e80 [ 208.680760][T27684] GPR12: 0000000000000000 c000201fff671280 0000000000000000 0000000000000002 [ 208.680760][T27684] GPR16: 0000000000000002 0000000000040001 c00020030f5a1000 c00020030f5a1548 [ 208.680760][T27684] GPR20: c0000000015fbad8 c00000000168c654 c000200361def818 c0000000005b4c10 [ 208.680760][T27684] GPR24: 0000000000000000 c0080000103365b8 c00020107dae0bd0 0000000000000400 [ 208.680760][T27684] GPR28: c00000000168c3a8 0000000000000000 0000000000000000 0000000000000000 [ 208.681014][T27684] NIP [0000000000000000] 0x0 [ 208.681065][T27684] LR [c0080000102c0048] ext4_iomap_end+0x8/0x30 [ext4] [ 208.681091][T27684] Call Trace: [ 208.681129][T27684] [c000200361def6b0] [c0000000005ac3bc] iomap_apply+0x20c/0x920 (unreliable) iomap_apply at fs/iomap/apply.c:80 (discriminator 4) [ 208.681173][T27684] [c000200361def7f0] [c0000000005b4adc] iomap_bmap+0xfc/0x160 iomap_bmap at fs/iomap/fiemap.c:142 [ 208.681228][T27684] [c000200361def850] [c0080000102c2c1c] ext4_bmap+0xa4/0x180 [ext4] ext4_bmap at fs/ext4/inode.c:3213 [ 208.681260][T27684] [c000200361def890] [c0000000004f71fc] bmap+0x4c/0x80 [ 208.681281][T27684] [c000200361def8c0] [c00800000fdb0acc] jbd2_journal_init_inode+0x44/0x1a0 [jbd2] jbd2_journal_init_inode at fs/jbd2/journal.c:1255 [ 208.681326][T27684] [c000200361def960] [c00800001031c808] ext4_load_journal+0x440/0x860 [ext4] [ 208.681371][T27684] [c000200361defa30] [c008000010322a14] ext4_fill_super+0x342c/0x3ab0 [ext4] [ 208.681414][T27684] [c000200361defba0] [c0000000004cb0bc] mount_bdev+0x25c/0x290 [ 208.681478][T27684] [c000200361defc40] [c008000010310250] ext4_mount+0x28/0x50 [ext4] [ 208.681520][T27684] [c000200361defc60] [c00000000053242c] legacy_get_tree+0x4c/0xb0 [ 208.681556][T27684] [c000200361defc90] [c0000000004c864c] vfs_get_tree+0x4c/0x130 [ 208.681593][T27684] [c000200361defd00] [c00000000050a1c8] do_mount+0xa18/0xc50 [ 208.681641][T27684] [c000200361defdd0] [c00000000050a9a8] sys_mount+0x158/0x180 [ 208.681679][T27684] [c000200361defe20] [c00000000000b3f8] system_call+0x5c/0x68 [ 208.681726][T27684] Instruction dump: [ 208.681747][T27684] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX [ 208.681797][T27684] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX [ 208.681839][T27684] ---[ end trace 4e9e2bab7f1d4048 ]--- [ 208.802259][T27684] [ 209.802373][T27684] Kernel panic - not syncing: Fatal exception
