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BUG: KASAN: use-after-free in debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:685
Read of size 8 at addr ffff8880978d8900 by task kworker/0:4/7749

CPU: 0 PID: 7749 Comm: kworker/0:4 Not tainted 5.1.0-rc2 #36
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events __blk_release_queue
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:685
 blk_trace_free+0x38/0x140 kernel/trace/blktrace.c:312
 blk_trace_cleanup kernel/trace/blktrace.c:339 [inline]
 __blk_trace_remove+0x78/0xa0 kernel/trace/blktrace.c:352
 blk_trace_shutdown+0x67/0x90 kernel/trace/blktrace.c:753
 __blk_release_queue+0x1dc/0x3a0 block/blk-sysfs.c:866
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x357/0x430 kernel/kthread.c:253
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 16238:
 save_stack+0x45/0xd0 mm/kasan/common.c:75
 set_track mm/kasan/common.c:87 [inline]
 __kasan_kmalloc mm/kasan/common.c:497 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:505
 slab_post_alloc_hook mm/slab.h:436 [inline]
 slab_alloc mm/slab.c:3392 [inline]
 kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3554
 __d_alloc+0x2e/0x8c0 fs/dcache.c:1622
 d_alloc+0x4d/0x2b0 fs/dcache.c:1701
 d_alloc_parallel+0xf4/0x1bc0 fs/dcache.c:2449
 __lookup_slow+0x1ab/0x500 fs/namei.c:1652
 lookup_slow+0x58/0x80 fs/namei.c:1686
 walk_component+0x74b/0x2000 fs/namei.c:1808
 link_path_walk.part.0+0x594/0x1340 fs/namei.c:2136
 link_path_walk fs/namei.c:2070 [inline]
 path_openat+0x202/0x46e0 fs/namei.c:3532
 do_filp_open+0x1a1/0x280 fs/namei.c:3563
 do_sys_open+0x3fe/0x5d0 fs/open.c:1063
 __do_sys_open fs/open.c:1081 [inline]
 __se_sys_open fs/open.c:1076 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1076
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
 save_stack+0x45/0xd0 mm/kasan/common.c:75
 set_track mm/kasan/common.c:87 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:459
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:467
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3764
 __d_free+0x20/0x30 fs/dcache.c:269
 __rcu_reclaim kernel/rcu/rcu.h:227 [inline]
 rcu_do_batch kernel/rcu/tree.c:2475 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2788 [inline]
 rcu_core+0x928/0x1390 kernel/rcu/tree.c:2769
 __do_softirq+0x266/0x95a kernel/softirq.c:293

The buggy address belongs to the object at ffff8880978d88c0
 which belongs to the cache dentry(33:syz1) of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff8880978d88c0, ffff8880978d89e0)
The buggy address belongs to the page:
page:ffffea00025e3600 count:1 mapcount:0 mapping:ffff888091dd6080 index:0xffff8880978d8b80
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00025e0c88 ffffea00023503c8 ffff888091dd6080
raw: ffff8880978d8b80 ffff8880978d8080 0000000100000008 ffff88805abca900
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88805abca900

Memory state around the buggy address:
 ffff8880978d8800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880978d8880: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880978d8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880978d8980: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880978d8a00: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
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