Hi, Been running some tests and I keep running into issues with hotplug. This looks similar to what Bart posted the other day, but it looks more deeply rooted than just having to protect the queue in generic_make_request_checks(). The test run is blktests, block/001. Current -git doesn't survive it. I've seen at least two different oopses, pasted below. [ 102.163442] NULL pointer dereference at 0000000000000010 [ 102.163444] PGD 0 P4D 0 [ 102.163447] Oops: 0000 [#1] PREEMPT SMP [ 102.163449] Modules linked in: [ 102.175540] sr 12:0:0:0: [sr2] scsi-1 drive [ 102.180112] scsi_debug crc_t10dif crct10dif_generic crct10dif_common nvme nvme_core sb_edac xl [ 102.186934] sr 12:0:0:0: Attached scsi CD-ROM sr2 [ 102.191896] sr_mod cdrom btrfs xor zstd_decompress zstd_compress xxhash lzo_compress zlib_defc [ 102.197169] sr 12:0:0:0: Attached scsi generic sg7 type 5 [ 102.203475] igb ahci libahci i2c_algo_bit libata dca [last unloaded: crc_t10dif] [ 102.203484] CPU: 43 PID: 4629 Comm: systemd-udevd Not tainted 4.16.0+ #650 [ 102.203487] Hardware name: Dell Inc. PowerEdge T630/0NT78X, BIOS 2.3.4 11/09/2016 [ 102.350882] RIP: 0010:sr_block_revalidate_disk+0x23/0x190 [sr_mod] [ 102.358299] RSP: 0018:ffff883ff357bb58 EFLAGS: 00010292 [ 102.364734] RAX: ffffffffa00b07d0 RBX: ffff883ff3058000 RCX: ffff883ff357bb66 [ 102.373220] RDX: 0000000000000003 RSI: 0000000000007530 RDI: ffff881fea631000 [ 102.381705] RBP: 0000000000000000 R08: ffff881fe4d38400 R09: 0000000000000000 [ 102.390185] R10: 0000000000000000 R11: 00000000000001b6 R12: 000000000800005d [ 102.398671] R13: 000000000800005d R14: ffff883ffd9b3790 R15: 0000000000000000 [ 102.407156] FS: 00007f7dc8e6d8c0(0000) GS:ffff883fff340000(0000) knlGS:0000000000000000 [ 102.417138] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 102.424066] CR2: 0000000000000010 CR3: 0000003ffda98005 CR4: 00000000003606e0 [ 102.432545] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 102.441024] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 102.449502] Call Trace: [ 102.452744] ? __invalidate_device+0x48/0x60 [ 102.458022] check_disk_change+0x4c/0x60 [ 102.462900] sr_block_open+0x16/0xd0 [sr_mod] [ 102.468270] __blkdev_get+0xb9/0x450 [ 102.472774] ? iget5_locked+0x1c0/0x1e0 [ 102.477568] blkdev_get+0x11e/0x320 [ 102.481969] ? bdget+0x11d/0x150 [ 102.486083] ? _raw_spin_unlock+0xa/0x20 [ 102.490968] ? bd_acquire+0xc0/0xc0 [ 102.495368] do_dentry_open+0x1b0/0x320 [ 102.500159] ? inode_permission+0x24/0xc0 [ 102.505140] path_openat+0x4e6/0x1420 [ 102.509741] ? cpumask_any_but+0x1f/0x40 [ 102.514630] ? flush_tlb_mm_range+0xa0/0x120 [ 102.519903] do_filp_open+0x8c/0xf0 [ 102.524305] ? __seccomp_filter+0x28/0x230 [ 102.529389] ? _raw_spin_unlock+0xa/0x20 [ 102.534283] ? __handle_mm_fault+0x7d6/0x9b0 [ 102.539559] ? list_lru_add+0xa8/0xc0 [ 102.544157] ? _raw_spin_unlock+0xa/0x20 [ 102.549047] ? __alloc_fd+0xaf/0x160 [ 102.553549] ? do_sys_open+0x1a6/0x230 [ 102.558244] do_sys_open+0x1a6/0x230 [ 102.562742] do_syscall_64+0x5a/0x100 [ 102.567336] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 and this one, similar to Barts: [ 4676.738069] NULL pointer dereference at 0000000000000154 [ 4676.738071] PGD 0 P4D 0 [ 4676.738073] Oops: 0000 [#1] PREEMPT SMP [ 4676.738075] Modules linked in: scsi_debug crc_t10dif nvme nvme_core loop configfs crct10dif_ge] [ 4676.859272] CPU: 10 PID: 16598 Comm: systemd-udevd Not tainted 4.16.0+ #651 [ 4676.867525] Hardware name: Dell Inc. PowerEdge T630/0NT78X, BIOS 2.3.4 11/09/2016 [ 4676.876765] RIP: 0010:blk_throtl_bio+0x45/0x9b0 [ 4676.882296] RSP: 0018:ffff881ff0c8bb38 EFLAGS: 00010246 [ 4676.888610] RAX: 0000000000000000 RBX: ffff881ffa273a40 RCX: 0000000000000000 [ 4676.897059] RDX: ffff881ffa273a40 RSI: 0000000000000000 RDI: 0000000000000000 [ 4676.905507] RBP: 0000000000000000 R08: ffff881ffa273ac0 R09: ffff881ff123f458 [ 4676.913955] R10: ffff881ff0c8bc70 R11: 0000000000001000 R12: 0000000000000000 [ 4676.922402] R13: ffffffff82600980 R14: ffff882081130000 R15: 0000000000000000 [ 4676.930856] FS: 00007fe63e5228c0(0000) GS:ffff881fff740000(0000) knlGS:0000000000000000 [ 4676.940773] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 4676.947667] CR2: 0000000000000154 CR3: 0000001fed2a0003 CR4: 00000000003606e0 [ 4676.956116] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 4676.964568] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 4676.973021] Call Trace: [ 4676.976229] generic_make_request_checks+0x640/0x660 [ 4676.982245] ? kmem_cache_alloc+0x37/0x190 [ 4676.987295] generic_make_request+0x29/0x2f0 [ 4676.992534] ? submit_bio+0x5c/0x110 [ 4676.996998] ? bio_alloc_bioset+0x99/0x1c0 [ 4677.002050] submit_bio+0x5c/0x110 [ 4677.006317] ? guard_bio_eod+0x42/0x120 [ 4677.011074] submit_bh_wbc.isra.49+0x132/0x160 [ 4677.016517] ? bh_uptodate_or_lock+0x90/0x90 [ 4677.021757] block_read_full_page+0x216/0x330 [ 4677.027095] ? check_disk_change+0x60/0x60 [ 4677.032144] ? __atime_needs_update+0x7f/0x190 [ 4677.037576] ? find_get_entry+0x98/0xf0 [ 4677.042329] ? pagecache_get_page+0x30/0x220 [ 4677.047567] ? touch_atime+0x27/0xb0 [ 4677.052029] generic_file_read_iter+0x60b/0x970 [ 4677.057561] ? _copy_to_user+0x56/0x70 [ 4677.062221] ? __seccomp_filter+0x28/0x230 [ 4677.067269] __vfs_read+0xd1/0x120 [ 4677.071539] vfs_read+0x9b/0x140 [ 4677.075614] ksys_read+0x45/0xa0 [ 4677.079686] do_syscall_64+0x5a/0x100 [ 4677.084241] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 [ 4677.090345] RIP: 0033:0x7fe63d6741f0 [ 4677.094808] RSP: 002b:00007ffcb901f918 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 4677.104143] RAX: ffffffffffffffda RBX: 000055b1645c33c0 RCX: 00007fe63d6741f0 [ 4677.112584] RDX: 0000000000000400 RSI: 000055b1645c33e8 RDI: 000000000000000f [ 4677.121037] RBP: 000055b1645c32b0 R08: 00007fe63d65f008 R09: 0000000000000430 [ 4677.129489] R10: 000055b1645c33d8 R11: 0000000000000246 R12: 0000000000000000 [ 4677.137934] R13: 0000000000000400 R14: 000055b1645c3300 R15: 0000000000000400 [ 4677.146385] Code: 85 f6 74 4e 48 63 05 ab 33 d6 00 4c 8b bc c6 c8 02 00 00 0f b7 43 14 f6 c4 0 [ 4677.168785] RIP: blk_throtl_bio+0x45/0x9b0 RSP: ffff881ff0c8bb38 -- Jens Axboe
