possible deadlock in percpu_down_write

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    7ec21823634d Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14ceda09400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=88e9a8a39dc0be2d
dashboard link: https://syzkaller.appspot.com/bug?extid=7bf81a3e18fab8a61966
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7bf81a3e18fab8a61966@xxxxxxxxxxxxxxxxxxxxxxxxx


======================================================
WARNING: possible circular locking dependency detected
4.19.0-rc7+ #282 Not tainted
------------------------------------------------------
syz-executor4/9907 is trying to acquire lock:
000000003db358c5 (&dup_mmap_sem){++++}, at: percpu_down_write+0xaf/0x540  
kernel/locking/percpu-rwsem.c:145

but task is already holding lock:
000000003d2ff532 (&uprobe->register_rwsem){+.+.}, at: __uprobe_register  
kernel/events/uprobes.c:922 [inline]
000000003d2ff532 (&uprobe->register_rwsem){+.+.}, at:  
uprobe_register+0x3dd/0x7c0 kernel/events/uprobes.c:941

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&uprobe->register_rwsem){+.+.}:
       down_write+0x8a/0x130 kernel/locking/rwsem.c:70
       __uprobe_register kernel/events/uprobes.c:922 [inline]
       uprobe_register+0x3dd/0x7c0 kernel/events/uprobes.c:941
       probe_event_enable+0x5f5/0xf30 kernel/trace/trace_uprobe.c:908
       trace_uprobe_register+0x4c9/0xcf0 kernel/trace/trace_uprobe.c:1193
       perf_trace_event_reg kernel/trace/trace_event_perf.c:124 [inline]
       perf_trace_event_init+0x50b/0x990 kernel/trace/trace_event_perf.c:199
       perf_uprobe_init+0x1e5/0x280 kernel/trace/trace_event_perf.c:328
       perf_uprobe_event_init+0xff/0x190 kernel/events/core.c:8474
       perf_try_init_event+0x137/0x2f0 kernel/events/core.c:9741
       perf_init_event kernel/events/core.c:9772 [inline]
       perf_event_alloc.part.93+0x23e6/0x35f0 kernel/events/core.c:10045
       perf_event_alloc kernel/events/core.c:10401 [inline]
       __do_sys_perf_event_open+0xa9c/0x2f30 kernel/events/core.c:10502
       __se_sys_perf_event_open kernel/events/core.c:10391 [inline]
       __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10391
       do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #2 (event_mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:925 [inline]
       __mutex_lock+0x166/0x1700 kernel/locking/mutex.c:1072
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
       perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:236
       tp_perf_event_destroy+0x15/0x20 kernel/events/core.c:8336
       _free_event+0x414/0x1610 kernel/events/core.c:4446
       put_event+0x48/0x60 kernel/events/core.c:4532
       perf_mmap_close+0x62f/0x1220 kernel/events/core.c:5515
       remove_vma+0xb1/0x180 mm/mmap.c:181
       remove_vma_list mm/mmap.c:2550 [inline]
       do_munmap+0x72d/0xf50 mm/mmap.c:2786
       mmap_region+0x6a4/0x1cd0 mm/mmap.c:1705
       do_mmap+0xa22/0x1230 mm/mmap.c:1535
       do_mmap_pgoff include/linux/mm.h:2298 [inline]
       vm_mmap_pgoff+0x213/0x2c0 mm/util.c:357
       ksys_mmap_pgoff+0x4da/0x660 mm/mmap.c:1585
       __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
       __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
       __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
       do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&mm->mmap_sem){++++}:
       down_write_killable+0x8d/0x150 kernel/locking/rwsem.c:84
       dup_mmap kernel/fork.c:431 [inline]
       dup_mm kernel/fork.c:1274 [inline]
       copy_mm kernel/fork.c:1329 [inline]
       copy_process+0x3648/0x8780 kernel/fork.c:1869
       _do_fork+0x1cb/0x11d0 kernel/fork.c:2166
       __do_sys_clone kernel/fork.c:2273 [inline]
       __se_sys_clone kernel/fork.c:2267 [inline]
       __x64_sys_clone+0xbf/0x150 kernel/fork.c:2267
       do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&dup_mmap_sem){++++}:
       lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
       down_write+0x8a/0x130 kernel/locking/rwsem.c:70
       percpu_down_write+0xaf/0x540 kernel/locking/percpu-rwsem.c:145
       register_for_each_vma+0xa0/0xee0 kernel/events/uprobes.c:797
       __uprobe_register kernel/events/uprobes.c:926 [inline]
       uprobe_register+0x47c/0x7c0 kernel/events/uprobes.c:941
       probe_event_enable+0x5f5/0xf30 kernel/trace/trace_uprobe.c:908
       trace_uprobe_register+0x4c9/0xcf0 kernel/trace/trace_uprobe.c:1193
       perf_trace_event_reg kernel/trace/trace_event_perf.c:124 [inline]
       perf_trace_event_init+0x50b/0x990 kernel/trace/trace_event_perf.c:199
       perf_uprobe_init+0x1e5/0x280 kernel/trace/trace_event_perf.c:328
       perf_uprobe_event_init+0xff/0x190 kernel/events/core.c:8474
       perf_try_init_event+0x137/0x2f0 kernel/events/core.c:9741
       perf_init_event kernel/events/core.c:9772 [inline]
       perf_event_alloc.part.93+0x23e6/0x35f0 kernel/events/core.c:10045
       perf_event_alloc kernel/events/core.c:10401 [inline]
       __do_sys_perf_event_open+0xa9c/0x2f30 kernel/events/core.c:10502
       __se_sys_perf_event_open kernel/events/core.c:10391 [inline]
       __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10391
       do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  &dup_mmap_sem --> event_mutex --> &uprobe->register_rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&uprobe->register_rwsem);
                               lock(event_mutex);
                               lock(&uprobe->register_rwsem);
  lock(&dup_mmap_sem);

 *** DEADLOCK ***

4 locks held by syz-executor4/9907:
 #0: 000000006bd41ed2 (&sig->cred_guard_mutex){+.+.}, at:  
__do_sys_perf_event_open+0x12fe/0x2f30 kernel/events/core.c:10482
 #1: 00000000c3cef6b0 (&pmus_srcu){....}, at: fdput include/linux/file.h:42  
[inline]
 #1: 00000000c3cef6b0 (&pmus_srcu){....}, at: perf_cgroup_connect  
kernel/events/core.c:925 [inline]
 #1: 00000000c3cef6b0 (&pmus_srcu){....}, at:  
perf_event_alloc.part.93+0x18a1/0x35f0 kernel/events/core.c:10040
 #2: 000000005feb8cff (event_mutex){+.+.}, at: perf_uprobe_init+0x1da/0x280  
kernel/trace/trace_event_perf.c:327
 #3: 000000003d2ff532 (&uprobe->register_rwsem){+.+.}, at:  
__uprobe_register kernel/events/uprobes.c:922 [inline]
 #3: 000000003d2ff532 (&uprobe->register_rwsem){+.+.}, at:  
uprobe_register+0x3dd/0x7c0 kernel/events/uprobes.c:941

stack backtrace:
CPU: 0 PID: 9907 Comm: syz-executor4 Not tainted 4.19.0-rc7+ #282
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 print_circular_bug.isra.33.cold.54+0x1bd/0x27d  
kernel/locking/lockdep.c:1221
 check_prev_add kernel/locking/lockdep.c:1861 [inline]
 check_prevs_add kernel/locking/lockdep.c:1974 [inline]
 validate_chain kernel/locking/lockdep.c:2415 [inline]
 __lock_acquire+0x33e4/0x4ec0 kernel/locking/lockdep.c:3411
 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
 down_write+0x8a/0x130 kernel/locking/rwsem.c:70
 percpu_down_write+0xaf/0x540 kernel/locking/percpu-rwsem.c:145
 register_for_each_vma+0xa0/0xee0 kernel/events/uprobes.c:797
 __uprobe_register kernel/events/uprobes.c:926 [inline]
 uprobe_register+0x47c/0x7c0 kernel/events/uprobes.c:941
 probe_event_enable+0x5f5/0xf30 kernel/trace/trace_uprobe.c:908
 trace_uprobe_register+0x4c9/0xcf0 kernel/trace/trace_uprobe.c:1193
 perf_trace_event_reg kernel/trace/trace_event_perf.c:124 [inline]
 perf_trace_event_init+0x50b/0x990 kernel/trace/trace_event_perf.c:199
 perf_uprobe_init+0x1e5/0x280 kernel/trace/trace_event_perf.c:328
 perf_uprobe_event_init+0xff/0x190 kernel/events/core.c:8474
 perf_try_init_event+0x137/0x2f0 kernel/events/core.c:9741
 perf_init_event kernel/events/core.c:9772 [inline]
 perf_event_alloc.part.93+0x23e6/0x35f0 kernel/events/core.c:10045
 perf_event_alloc kernel/events/core.c:10401 [inline]
 __do_sys_perf_event_open+0xa9c/0x2f30 kernel/events/core.c:10502
 __se_sys_perf_event_open kernel/events/core.c:10391 [inline]
 __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10391
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457569
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fbbcbb44c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 00007fbbcbb456d4
R13: 00000000004c2f7c R14: 00000000004d4818 R15: 00000000ffffffff
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'input16' (00000000b196811a): kobject_cleanup, parent            
(null)
kobject: 'input16' (00000000b196811a): calling ktype release
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'input16': free name
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'serio3' (0000000052b87646): kobject_add_internal:  
parent: 'devices', set: 'devices'
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'serio3' (0000000052b87646): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'serio3' (0000000052b87646): fill_kobj_path: path  
= '/devices/serio3'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'input17' (0000000039d05571): kobject_cleanup, parent            
(null)
kobject: 'input17' (0000000039d05571): calling ktype release
kobject: 'input17': free name
kobject: 'input18' (00000000a9a434f8): kobject_cleanup, parent            
(null)
kobject: 'input18' (00000000a9a434f8): calling ktype release
kobject: 'input18': free name
kobject: 'serio2' (000000005b4912c2): kobject_uevent_env
kobject: 'serio2' (000000005b4912c2): fill_kobj_path: path  
= '/devices/serio2'
kobject: 'serio2' (000000005b4912c2): kobject_cleanup, parent            
(null)
kobject: 'serio2' (000000005b4912c2): calling ktype release
kobject: 'serio2': free name
kobject: 'serio3' (0000000052b87646): kobject_uevent_env
kobject: 'serio3' (0000000052b87646): fill_kobj_path: path  
= '/devices/serio3'
kobject: 'serio3' (0000000052b87646): kobject_cleanup, parent            
(null)
kobject: 'serio3' (0000000052b87646): calling ktype release
kobject: 'serio3': free name
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'nullb0' (00000000a448ce71): kobject_uevent_env
kobject: 'nullb0' (00000000a448ce71): fill_kobj_path: path  
= '/devices/virtual/block/nullb0'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop0' (000000009a170905): kobject_uevent_env
kobject: 'loop0' (000000009a170905): fill_kobj_path: path  
= '/devices/virtual/block/loop0'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop1' (00000000761a47af): kobject_uevent_env
kobject: 'loop1' (00000000761a47af): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop3' (00000000f1a88a52): kobject_uevent_env
kobject: 'loop3' (00000000f1a88a52): fill_kobj_path: path  
= '/devices/virtual/block/loop3'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop2' (00000000ebdc5361): kobject_uevent_env
kobject: 'loop2' (00000000ebdc5361): fill_kobj_path: path  
= '/devices/virtual/block/loop2'
kobject: 'loop4' (00000000423f8963): kobject_uevent_env
kobject: 'loop4' (00000000423f8963): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
kobject: 'loop5' (0000000061b48517): kobject_uevent_env
kobject: 'loop5' (0000000061b48517): fill_kobj_path: path  
= '/devices/virtual/block/loop5'


---
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