FYI, we noticed the below changes on

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
commit df4c0e36f1b1782b0611a77c52cc240e5c4752dd ("fs: dcache: manually unpoison dname after allocation to shut up kasan's reports")


The commit fixed a KASan bug, but introduced or revealed a soft lockup
issue as follow.


[  116.546697] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]
[  116.546697] irq event stamp: 3018750
[  116.546697] hardirqs last  enabled at (3018749): [<ffffffff8224f36c>] restore_args+0x0/0x30
[  116.546697] hardirqs last disabled at (3018750): [<ffffffff8224f65d>] apic_timer_interrupt+0x6d/0x80
[  116.546697] softirqs last  enabled at (3018748): [<ffffffff810de898>] __do_softirq+0x417/0x65b
[  116.546697] softirqs last disabled at (3018743): [<ffffffff810ded30>] irq_exit+0x55/0xc3
[  116.546697] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.19.0-05249-gdf4c0e3 #1
[  116.546697] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[  116.546697] task: ffff88002f3f0000 ti: ffff88002f3f8000 task.ti: ffff88002f3f8000
[  116.546697] RIP: 0010:[<ffffffff8125fdf9>]  [<ffffffff8125fdf9>] __asan_load4+0x12/0x91
[  116.546697] RSP: 0000:ffff88002f3fbdc8  EFLAGS: 00000282
[  116.546697] RAX: ffff7fffffffffff RBX: 0000000000000000 RCX: dffffc0000000000
[  116.546697] RDX: fffffbfff0763087 RSI: ffffffff83b18b10 RDI: ffffffff83b1803c
[  116.546697] RBP: ffff88002f3fbdf8 R08: 0000000000000001 R09: fffffbfff0763074
[  116.546697] R10: ffffffff83b183a7 R11: fffffbfff0763074 R12: ffff880038d29003
[  116.546697] R13: ffffed00071a5200 R14: ffffffff818cfadb R15: ffff88002f3fbdf8
[  116.546697] FS:  0000000000000000(0000) GS:ffff88002f600000(0000) knlGS:0000000000000000
[  116.546697] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  116.546697] CR2: 0000000000000000 CR3: 0000000002793000 CR4: 00000000000006f0
[  116.546697] Stack:
[  116.546697]  ffffffff83b18d5c ffffffff83b18b08 ffffffff83b18878 ffffffff83b18b10
[  116.546697]  ffffffff83b18868 0000000000000000 ffff88002f3fbe48 ffffffff8223c4d3
[  116.546697]  0000000000000000 c4400d6283b18d40 0000000000000202 0000000000000d98
[  116.546697] Call Trace:
[  116.546697]  [<ffffffff8223c4d3>] insert_augmented+0x52/0xf5
[  116.546697]  [<ffffffff82b7b4ef>] rbtree_test_init+0x151/0x205
[  116.546697]  [<ffffffff82b7b39e>] ? glob_init+0x11c/0x11c
[  116.546697]  [<ffffffff82b222dc>] do_one_initcall+0x105/0x197
[  116.546697]  [<ffffffff82b22501>] kernel_init_freeable+0x193/0x22e
[  116.546697]  [<ffffffff8222ba4b>] ? rest_init+0x14d/0x14d
[  116.546697]  [<ffffffff8222ba59>] kernel_init+0xe/0xdf
[  116.546697]  [<ffffffff8224e5fc>] ret_from_fork+0x7c/0xb0
[  116.546697]  [<ffffffff8222ba4b>] ? rest_init+0x14d/0x14d
[  116.546697] Code: 38 00 74 13 48 8b 4d 08 ba 01 00 00 00 be 02 00 00 00 e8 e0 09 00 00 c9 c3 55 48 b8 ff ff ff ff ff 7f ff ff 48 89 e5 48 83 ec 30 <48> 39 c7 77 23 48 8b 45 08 48 89 7d d8 48 8d 7d d8 48 c7 45 e8 
[  116.546697] Kernel panic - not syncing: softlockup: hung tasks
[  116.546697] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G             L  3.19.0-05249-gdf4c0e3 #1
[  116.546697] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[  116.546697]  0000000000000000 0000000000000000 0000000000000000 ffff88002f603d48
[  116.546697]  ffffffff8223bcf7 fffffbfff074360b ffffffff8263d4e2 ffff88002f603dc8
[  116.546697]  ffffffff82234300 ffff88002f603dc8 ffffffff00000008 ffff88002f603dd8
[  116.546697] Call Trace:
[  116.546697]  <IRQ>  [<ffffffff8223bcf7>] dump_stack+0x4c/0x65
[  116.546697]  [<ffffffff82234300>] panic+0xed/0x231
[  116.546697]  [<ffffffff811adf9d>] watchdog_timer_fn+0x1d2/0x1f8
[  116.546697]  [<ffffffff811addcb>] ? __touch_watchdog+0x1c/0x1c
[  116.546697]  [<ffffffff8117083e>] __run_hrtimer+0x283/0x6a2
[  116.546697]  [<ffffffff81171aaf>] hrtimer_run_queues+0x126/0x145
[  116.546697]  [<ffffffff8116ff2f>] run_local_timers+0xe/0x1a
[  116.546697]  [<ffffffff8116ff62>] update_process_times+0x27/0x54
[  116.546697]  [<ffffffff81181e76>] tick_nohz_handler+0x101/0x164
[  116.546697]  [<ffffffff81040dbc>] local_apic_timer_interrupt+0x78/0x80
[  116.546697]  [<ffffffff8225144c>] smp_apic_timer_interrupt+0x57/0x69
[  116.546697]  [<ffffffff8224f662>] apic_timer_interrupt+0x72/0x80
[  116.546697]  <EOI>  [<ffffffff8125fdf9>] ? __asan_load4+0x12/0x91
[  116.546697]  [<ffffffff8223c4d3>] insert_augmented+0x52/0xf5
[  116.546697]  [<ffffffff82b7b4ef>] rbtree_test_init+0x151/0x205
[  116.546697]  [<ffffffff82b7b39e>] ? glob_init+0x11c/0x11c
[  116.546697]  [<ffffffff82b222dc>] do_one_initcall+0x105/0x197
[  116.546697]  [<ffffffff82b22501>] kernel_init_freeable+0x193/0x22e
[  116.546697]  [<ffffffff8222ba4b>] ? rest_init+0x14d/0x14d
[  116.546697]  [<ffffffff8222ba59>] kernel_init+0xe/0xdf
[  116.546697]  [<ffffffff8224e5fc>] ret_from_fork+0x7c/0xb0
[  116.546697]  [<ffffffff8222ba4b>] ? rest_init+0x14d/0x14d
[  116.546697] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffff9fffffff)


Thanks,
Ying Huang