FYI, we noticed the following commit:

commit: 165a5e22fafb127ecb5914e12e8c32a1f0d3f820 ("block: Move bdi_unregister() to del_gendisk()")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

in testcase: trinity
with following parameters:

	runtime: 300s

test-description: Trinity is a linux system call fuzz tester.
test-url: http://codemonkey.org.uk/projects/trinity/


on test machine: qemu-system-x86_64 -enable-kvm -m 420M

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+-----------------------------------------------------------------------------------------------------+------------+------------+
|                                                                                                     | 113285b473 | 165a5e22fa |
+-----------------------------------------------------------------------------------------------------+------------+------------+
| boot_successes                                                                                      | 32         | 14         |
| boot_failures                                                                                       | 1          | 27         |
| invoked_oom-killer:gfp_mask=0x                                                                      | 1          |            |
| Mem-Info                                                                                            | 1          |            |
| page_allocation_failure:order:#,mode:#(GFP_USER),nodemask=(null)                                    | 1          |            |
| Out_of_memory:Kill_process                                                                          | 1          |            |
| page_allocation_failure:order:#,mode:#(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOTRACK),nodemask=(null) | 1          |            |
| BUG_kmalloc-#(Not_tainted):Poison_overwritten                                                       | 0          | 23         |
| INFO:#-#.First_byte#instead_of                                                                      | 0          | 23         |
| INFO:Allocated_in_bdi_init_age=#cpu=#pid=                                                           | 0          | 23         |
| INFO:Freed_in_wb_congested_put_age=#cpu=#pid=                                                       | 0          | 23         |
| INFO:Slab#objects=#used=#fp=0x(null)flags=                                                          | 0          | 23         |
| INFO:Object#@offset=#fp=                                                                            | 0          | 23         |
| BUG:kernel_hang_in_test_stage                                                                       | 0          | 2          |
| BUG:kernel_hang_in_boot_stage                                                                       | 0          | 2          |
+-----------------------------------------------------------------------------------------------------+------------+------------+



[   17.819559] sd 0:0:0:0: [sdb] Write Protect is off
[   17.819562] sd 0:0:0:0: [sdb] Mode Sense: 73 00 10 08
[   17.823330] sd 0:0:0:0: [sdb] Write cache: enabled, read cache: enabled, supports DPO and FUA
[   17.826134] slram: not enough parameters.
[   17.830848] =============================================================================
[   17.831013] BUG kmalloc-16 (Not tainted): Poison overwritten
[   17.831013] -----------------------------------------------------------------------------
[   17.831013] 
[   17.831013] Disabling lock debugging due to kernel taint
[   17.831013] INFO: 0xffff88001296ddc8-0xffff88001296ddd0. First byte 0x6a instead of 0x6b
[   17.831013] INFO: Allocated in bdi_init+0x85/0x31d age=119 cpu=0 pid=161
[   17.831013] 	___slab_alloc+0x479/0x4c6
[   17.831013] 	__slab_alloc+0x41/0x71
[   17.831013] 	kmem_cache_alloc+0x57/0xc2
[   17.831013] 	bdi_init+0x85/0x31d
[   17.831013] 	bdi_alloc_node+0x3f/0x53


To reproduce:

        git clone https://github.com/01org/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script  # job-script is attached in this email



Thanks,
Ying Huang