Hi, The following KASAN warning is found when running some random workloads on the latest linus tree: [ 3322.073327] ================================================================== [ 3322.074886] BUG: KASAN: use-after-free in bfq_bfqq_expire+0x8ae/0x925 [ 3322.075800] Write of size 4 at addr ffff88816457e810 by task swapper/3/0 [ 3322.076736] [ 3322.076969] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.0.0_6cdc577a18a6_master+ #1 [ 3322.078035] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-2.fc27 04/01/2014 [ 3322.079230] Call Trace: [ 3322.079602] <IRQ> [ 3322.079911] dump_stack+0x9a/0xe6 [ 3322.080408] ? bfq_bfqq_expire+0x8ae/0x925 [ 3322.080994] print_address_description+0x6e/0x239 [ 3322.081671] ? bfq_bfqq_expire+0x8ae/0x925 [ 3322.082251] ? bfq_bfqq_expire+0x8ae/0x925 [ 3322.082849] kasan_report+0x146/0x18b [ 3322.083390] ? rcu_read_lock_sched_held+0x25/0x63 [ 3322.084057] ? bfq_bfqq_expire+0x8ae/0x925 [ 3322.084663] bfq_bfqq_expire+0x8ae/0x925 [ 3322.085235] bfq_idle_slice_timer+0xc4/0xe2 [ 3322.085853] __hrtimer_run_queues+0x3b4/0x563 [ 3322.086502] ? bfq_dispatch_request+0xfe5/0xfe5 [ 3322.087159] ? hrtimer_cancel+0x1b/0x1b [ 3322.087732] ? kvm_clock_read+0x14/0x23 [ 3322.088283] ? ktime_get_update_offsets_now+0x126/0x1d4 [ 3322.089049] hrtimer_interrupt+0x1a9/0x335 [ 3322.089678] smp_apic_timer_interrupt+0x19d/0x2ab [ 3322.090341] apic_timer_interrupt+0xf/0x20 [ 3322.090936] </IRQ> [ 3322.091251] RIP: 0010:native_safe_halt+0x2/0x3 [ 3322.091898] Code: 63 02 df f0 83 44 24 fc 00 48 89 df e8 13 d1 7c ff 48 8b 03 a8 08 74 0b 65 81 25 65 cc 45 7e ff ff ff 7f 5b 5d 41 5c c3 fb f4 <c3> f4 c3 0f 1f 44 00 00 41 56 41 55 41 54 55 53 e8 f4 36 5d ff e8 [ 3322.094474] RSP: 0018:ffff888107fafdc0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 [ 3322.095535] RAX: 1ffff11020ff4900 RBX: 0000000000000000 RCX: ffffffff8115cc60 [ 3322.096539] RDX: 1ffffffff05df159 RSI: 0000000000000007 RDI: ffff888107fa4d5c [ 3322.097542] RBP: 0000000000000000 R08: dffffc0000000000 R09: 0000000000000001 [ 3322.098529] R10: ffffed102db3fc90 R11: ffffed102db3fc8f R12: 1ffff11020ff5fbf [ 3322.099516] R13: 0000000000000003 R14: ffff888107fa4040 R15: 0000000000000000 [ 3322.100529] ? lockdep_hardirqs_on+0x26e/0x27b [ 3322.101171] default_idle+0xd9/0x1a8 [ 3322.101698] do_idle+0x162/0x2b2 [ 3322.102165] ? arch_cpu_idle_exit+0x28/0x28 [ 3322.102767] ? schedule_idle+0x3b/0x44 [ 3322.103323] cpu_startup_entry+0x1d/0x1f [ 3322.103807] start_secondary+0x270/0x2ad [ 3322.104323] ? set_cpu_sibling_map+0x8a3/0x8a3 [ 3322.104999] secondary_startup_64+0xa4/0xb0 [ 3322.105636] [ 3322.105865] Allocated by task 22687: [ 3322.106380] kmem_cache_alloc_node+0x187/0x2a8 [ 3322.107014] bfq_get_queue+0x22a/0x503 [ 3322.107552] bfq_get_bfqq_handle_split+0xa6/0x1ce [ 3322.108195] bfq_init_rq+0x3ec/0xc3d [ 3322.108707] bfq_insert_requests+0x14d/0x14c3 [ 3322.109319] blk_mq_sched_insert_request+0x1ae/0x299 [ 3322.109953] blk_mq_make_request+0x83d/0x887 [ 3322.110574] generic_make_request+0x3f5/0x68b [ 3322.111097] submit_bio+0x1f2/0x239 [ 3322.111529] submit_bh_wbc+0x2c1/0x2d2 [ 3322.112024] ll_rw_block+0xc4/0xe5 [ 3322.112514] ext4_bread+0x9d/0x12b [ 3322.112998] __ext4_read_dirblock+0x36/0x3b8 [ 3322.113559] htree_dirblock_to_tree+0xa5/0x282 [ 3322.114094] ext4_htree_fill_tree+0x1bc/0x483 [ 3322.114625] ext4_readdir+0x4f4/0xe6e [ 3322.115071] iterate_dir+0x11f/0x204 [ 3322.115532] __se_sys_getdents+0x117/0x1ce [ 3322.116109] do_syscall_64+0xa1/0x245 [ 3322.116636] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 3322.117338] [ 3322.117571] Freed by task 0: [ 3322.117979] kmem_cache_free+0x139/0x28e [ 3322.118458] bfq_bfqq_expire+0x89d/0x925 [ 3322.118920] bfq_idle_slice_timer+0xc4/0xe2 [ 3322.119430] __hrtimer_run_queues+0x3b4/0x563 [ 3322.119956] hrtimer_interrupt+0x1a9/0x335 [ 3322.120506] smp_apic_timer_interrupt+0x19d/0x2ab [ 3322.121069] [ 3322.121267] The buggy address belongs to the object at ffff88816457e648 [ 3322.121267] which belongs to the cache bfq_queue of size 464 [ 3322.122902] The buggy address is located 456 bytes inside of [ 3322.122902] 464-byte region [ffff88816457e648, ffff88816457e818) [ 3322.124268] The buggy address belongs to the page: [ 3322.124891] page:ffffea0005915f00 count:1 mapcount:0 mapping:ffff88807f9e3bc0 index:0x0 compound_mapcount: 0 [ 3322.126101] flags: 0x57ffffc0010200(slab|head) [ 3322.126605] raw: 0057ffffc0010200 ffffea0005824b08 ffffea0005af4008 ffff88807f9e3bc0 [ 3322.127645] raw: 0000000000000000 0000000000140014 00000001ffffffff 0000000000000000 [ 3322.128673] page dumped because: kasan: bad access detected [ 3322.129333] [ 3322.129534] Memory state around the buggy address: [ 3322.130107] ffff88816457e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 3322.130953] ffff88816457e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 3322.131829] >ffff88816457e800: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc [ 3322.132816] ^ [ 3322.133260] ffff88816457e880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 3322.134091] ffff88816457e900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fb [ 3322.134946] ================================================================== Thanks, Ming
