Hello, If I merge Jens' for-next branch with Linus' master branch and boot the resulting kernel in a VM then the call trace shown below appears. This call trace does not appear when building and booting the code from Linus' master branch. Is this perhaps a regression?
WARNING: CPU: 1 PID: 257 at block/blk-throttle.c:2128 blk_throtl_bio+0xc00/0x1120 Modules linked in: floppy(+) virtio_blk(+) virtio_net net_failover failover i2c_piix4 pata_acpi CPU: 1 PID: 257 Comm: systemd-udevd Not tainted 4.20.0-rc5-dbg+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 RIP: 0010:blk_throtl_bio+0xc00/0x1120 Call Trace: ? create_task_io_context+0x1a2/0x1e0 ? lock_downgrade+0x2e0/0x2e0 ? kasan_check_read+0x11/0x20 ? do_raw_spin_unlock+0xa8/0x140 ? preempt_count_sub+0x18/0xd0 generic_make_request_checks+0x432/0xcc0 ? trace_event_raw_event_block_rq_requeue+0x290/0x290 ? __lock_acquire+0x5b0/0x17e0 ? __bio_associate_blkg.isra.33+0x1d0/0x3c0 generic_make_request+0x151/0x950 ? blk_queue_enter+0x7e0/0x7e0 submit_bio+0x9b/0x250 ? submit_bio+0x9b/0x250 ? generic_make_request+0x950/0x950 ? guard_bio_eod+0x120/0x2d0 submit_bh_wbc+0x2df/0x310 block_read_full_page+0x34c/0x4c0 ? I_BDEV+0x20/0x20 ? __bread_gfp+0x170/0x170 ? add_to_page_cache_locked+0x20/0x20 ? blkdev_writepages+0x10/0x10 ? blkdev_writepages+0x10/0x10 blkdev_readpage+0x18/0x20 do_read_cache_page+0x5ed/0xbf0 ? blkdev_writepages+0x10/0x10 ? find_valid_gpt+0x1a8/0x8b0 ? efi_partition+0x147/0x6c1 ? check_partition+0x1b2/0x314 ? blkdev_get+0x1f2/0x5a0 ? __device_add_disk+0x6c1/0x7e0 ? device_add_disk+0x13/0x20 ? pagecache_get_page+0x420/0x420 ? driver_probe_device+0x118/0x180 ? __driver_attach+0x167/0x190 ? bus_for_each_dev+0x105/0x160 ? driver_attach+0x2b/0x30 ? bus_add_driver+0x23d/0x350 ? driver_register+0xdc/0x160 ? register_virtio_driver+0x3c/0x60 ? init+0x51/0x1000 [virtio_blk] ? do_one_initcall+0xb4/0x3a1 ? do_init_module+0x103/0x360 ? load_module+0x443e/0x4630 ? __do_sys_finit_module+0x12d/0x1b0 ? __x64_sys_finit_module+0x43/0x50 ? do_syscall_64+0x71/0x210 ? entry_SYSCALL_64_after_hwframe+0x49/0xbe ? match_held_lock+0x20/0x250 ? match_held_lock+0x35/0x250 ? blkdev_writepages+0x10/0x10 read_cache_page+0x3a/0x50 read_dev_sector+0x64/0x170 read_lba+0x1f9/0x3a0 ? msdos_partition+0x1370/0x1370 ? find_valid_gpt+0x1a8/0x8b0 ? kmem_cache_alloc_trace+0x151/0x340 ? find_valid_gpt+0x1a8/0x8b0 find_valid_gpt+0x1c6/0x8b0 ? is_gpt_valid.part.5+0x640/0x640 ? __alloc_pages_nodemask+0x1c4/0x4d0 ? lockdep_hardirqs_on+0x182/0x260 ? get_page_from_freelist+0x648/0x2070 ? mark_lock+0x69/0x8d0 ? trace_hardirqs_on+0x24/0x130 ? kasan_unpoison_shadow+0x35/0x50 ? get_page_from_freelist+0x648/0x2070 ? __asan_loadN+0xf/0x20 ? widen_string+0x73/0x170 ? __asan_loadN+0xf/0x20 ? widen_string+0x73/0x170 ? get_page_from_freelist+0x1eea/0x2070 ? set_precision+0x90/0x90 ? string+0x135/0x180 efi_partition+0x147/0x6c1 ? format_decode+0xce/0x550 ? enable_ptr_key_workfn+0x30/0x30 ? find_valid_gpt+0x8b0/0x8b0 ? vsnprintf+0x11d/0x820 ? pointer+0x4d0/0x4d0 ? snprintf+0x88/0xa0 ? snprintf+0x88/0xa0 ? vsprintf+0x20/0x20 ? find_valid_gpt+0x8b0/0x8b0 check_partition+0x1b2/0x314 rescan_partitions+0x13b/0x440 __blkdev_get+0x61f/0x930 ? check_disk_change+0xa0/0xa0 ? lock_downgrade+0x2e0/0x2e0 ? var_wake_function+0x90/0x90 blkdev_get+0x1f2/0x5a0 ? preempt_count_sub+0x18/0xd0 ? _raw_spin_unlock+0x31/0x50 ? bd_may_claim+0x80/0x80 ? bdget+0x26b/0x280 ? blkdev_writepage+0x20/0x20 ? kasan_check_read+0x11/0x20 ? kobject_put+0x23/0x220 __device_add_disk+0x6c1/0x7e0 ? blk_alloc_devt+0x150/0x150 ? __asan_storeN+0x12/0x20 device_add_disk+0x13/0x20 virtblk_probe+0x839/0xace [virtio_blk] ? virtblk_restore+0xd0/0xd0 [virtio_blk] ? mutex_unlock+0x12/0x20 ? kernfs_activate+0xd0/0xe0 ? kasan_check_write+0x14/0x20 ? kernfs_put+0x2c/0x280 ? vring_transport_features+0x19/0x70 ? vp_finalize_features+0xe6/0x160 ? vp_get_status+0x29/0x30 ? virtio_finalize_features+0xbe/0xe0 virtio_dev_probe+0x27d/0x390 really_probe+0x191/0x560 ? driver_probe_device+0x180/0x180 driver_probe_device+0x118/0x180 ? driver_probe_device+0x180/0x180 __driver_attach+0x167/0x190 bus_for_each_dev+0x105/0x160 ? subsys_dev_iter_exit+0x10/0x10 ? kasan_check_read+0x11/0x20 ? preempt_count_sub+0x18/0xd0 ? _raw_spin_unlock+0x31/0x50 driver_attach+0x2b/0x30 bus_add_driver+0x23d/0x350 driver_register+0xdc/0x160 ? 0xffffffffa0070000 register_virtio_driver+0x3c/0x60 init+0x51/0x1000 [virtio_blk] do_one_initcall+0xb4/0x3a1 ? trace_event_raw_event_initcall_finish+0x120/0x120 ? kasan_unpoison_shadow+0x35/0x50 ? __asan_register_globals+0x7b/0xa0 do_init_module+0x103/0x360 load_module+0x443e/0x4630 ? module_frob_arch_sections+0x20/0x20 ? vfs_read+0xe6/0x1e0 ? kernel_read+0x79/0xa0 ? kasan_check_write+0x14/0x20 ? kernel_read_file+0x259/0x310 ? do_mmap+0x431/0x6c0 __do_sys_finit_module+0x12d/0x1b0 ? __do_sys_finit_module+0x12d/0x1b0 ? __do_sys_init_module+0x200/0x200 ? kasan_check_write+0x14/0x20 ? fput+0x1d/0xc0 ? do_syscall_64+0x19/0x210 ? entry_SYSCALL_64_after_hwframe+0x49/0xbe __x64_sys_finit_module+0x43/0x50 do_syscall_64+0x71/0x210 entry_SYSCALL_64_after_hwframe+0x49/0xbe
