Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: e3953975b6a7b35788f3141689f2745e8200438d ("btrfs: Add load read policy")
https://github.com/kdave/btrfs-devel.git dev/raid-policy


in testcase: ltp
version: ltp-x86_64-14c1f76-1_20210101
with following parameters:

	disk: 1HDD
	fs: ext4
	test: syscalls-02
	ucode: 0xe2

test-description: The LTP testsuite contains a collection of tools for testing the Linux kernel and related features.
test-url: http://linux-test-project.github.io/


on test machine: 4 threads Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz with 32G memory

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


If you fix the issue, kindly add following tag
Reported-by: kernel test robot <redacted>



[  106.779345] BTRFS info (device loop0): disk space caching is enabled
[  106.785297] cutime=0 cstime=0
[  106.786322] BTRFS info (device loop0): has skinny extents
[  106.792681]
[  106.793102] <<<test_end>>>
[  106.796259] kobject (00000000b3dd42e0): tried to init an initialized object, something is seriously wrong.
[  106.801056]
[  106.801391] <<<test_start>>>
[  106.802549] CPU: 1 PID: 3870 Comm: move_mount02 Tainted: G          I       5.11.0-rc5-00082-ge3953975b6a7 #1
[  106.802551] Hardware name: Dell Inc. OptiPlex 7040/0Y7WYT, BIOS 1.1.1 10/07/2015
[  106.802552] Call Trace:
[  106.805261]
[  106.814921] dump_stack (kbuild/src/consumer/lib/dump_stack.c:122) 
[  106.817007] tag=fork04 stime=1612082759
[  106.819294] kobject_init.cold (kbuild/src/consumer/lib/kobject.c:365) 
[  106.829219]
[  106.836614]  kobject_init_and_add+0x35/0xa0
[  106.836617]  ? kmem_cache_alloc_trace+0x36e/0x460
[  106.839404] cmdline="fork04"
[  106.840552]  btrfs_sysfs_add_fsid+0xec/0x140 [btrfs]
[  106.843871]
[  106.847707]  open_ctree+0x8ef/0xe46 [btrfs]
[  106.851876] contacts=""
[  106.853121]  btrfs_mount_root.cold+0x13/0xfa [btrfs]
[  106.857311]
[  106.862025]  ? _cond_resched+0x19/0x40
[  106.862028]  ? __kmalloc_track_caller+0x5e/0x4a0
[  106.865249] analysis=exit
[  106.869884]  ? _cond_resched+0x19/0x40
[  106.869886]  legacy_get_tree+0x27/0x40
[  106.869889]  vfs_get_tree+0x25/0xc0
[  106.871384]
[  106.875571]  fc_mount+0xe/0x40
[  106.875573]  vfs_kern_mount+0x71/0xa0
[  106.878383] <<<test_output>>>
[  106.883004]  btrfs_mount+0x13b/0x3e0 [btrfs]
[  106.884513]
[  106.888270]  ? security_file_alloc+0x48/0xa0
[  106.894362] fork04      1  TPASS  :  Env var TERM unchanged after fork(): vt220
[  106.895523]  ? __alloc_file+0x89/0xe0
[  106.895525]  ? kmem_cache_alloc+0x2b5/0x460
[  106.895527]  ? alloc_empty_file+0x63/0xc0
[  106.899284]
[  106.903029]  ? _cond_resched+0x19/0x40
[  106.903031]  ? legacy_get_tree+0x27/0x40
[  106.908684] fork04      2  TPASS  :  Env var NoTSetzWq unchanged after fork(): getenv() does not find variable set
[  106.911066]  ? btrfs_show_options+0x660/0x660 [btrfs]
[  106.915340]
[  106.918307]  legacy_get_tree+0x27/0x40
[  106.918309]  vfs_get_tree+0x25/0xc0
[  106.924161] fork04      3  TPASS  :  Env var TESTPROG unchanged after fork(): FRKTCS04
[  106.928342]  __x64_sys_fsconfig+0x460/0x580
[  106.928344]  do_syscall_64+0x33/0x40
[  106.935662]
[  106.939323]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  106.939326] RIP: 0033:0x7f523b2d8f59


To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
Oliver Sang