INFO: task hung in mpage_prepare_extent_to_map

From: syzbot
Date: Mon Oct 28 2019 - 15:52:14 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 12d61c69 Add linux-next specific files for 20191024
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15a0fa97600000
kernel config: https://syzkaller.appspot.com/x/.config?x=afb75fd8c9fd5ed8
dashboard link: https://syzkaller.appspot.com/bug?extid=efb9e48b9fbdc49bb34a
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13a63dc4e00000

The bug was bisected to:

commit 9c61acffe2b8833152041f7b6a02d1d0a17fd378
Author: Song Liu <songliubraving@xxxxxx>
Date: Wed Oct 23 00:24:28 2019 +0000

mm,thp: recheck each page before collapsing file THP

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13eb6ec0e00000
final crash: https://syzkaller.appspot.com/x/report.txt?x=101b6ec0e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=17eb6ec0e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+efb9e48b9fbdc49bb34a@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 9c61acffe2b8 ("mm,thp: recheck each page before collapsing file THP")

INFO: task khugepaged:1084 blocked for more than 143 seconds.
Not tainted 5.4.0-rc4-next-20191024 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
khugepaged D27568 1084 2 0x80004000
Call Trace:
context_switch kernel/sched/core.c:3384 [inline]
__schedule+0x94a/0x1e70 kernel/sched/core.c:4069
schedule+0xd9/0x260 kernel/sched/core.c:4136
io_schedule+0x1c/0x70 kernel/sched/core.c:5780
wait_on_page_bit_common mm/filemap.c:1175 [inline]
__lock_page+0x422/0xab0 mm/filemap.c:1383
lock_page include/linux/pagemap.h:480 [inline]
mpage_prepare_extent_to_map+0xb3f/0xf90 fs/ext4/inode.c:2668
ext4_writepages+0xb6a/0x2e70 fs/ext4/inode.c:2866
? 0xffffffff81000000
do_writepages+0xfa/0x2a0 mm/page-writeback.c:2344
__filemap_fdatawrite_range+0x2bc/0x3b0 mm/filemap.c:421
__filemap_fdatawrite mm/filemap.c:429 [inline]
filemap_flush+0x24/0x30 mm/filemap.c:456
collapse_file+0x36b1/0x41a0 mm/khugepaged.c:1652
khugepaged_scan_file mm/khugepaged.c:1890 [inline]
khugepaged_scan_mm_slot mm/khugepaged.c:1988 [inline]
khugepaged_do_scan mm/khugepaged.c:2072 [inline]
khugepaged+0x2da9/0x4360 mm/khugepaged.c:2117
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Showing all locks held in the system:
4 locks held by kworker/u4:0/7:
#0: ffff8880a8284d28 ((wq_completion)writeback){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8880a8284d28 ((wq_completion)writeback){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8880a8284d28 ((wq_completion)writeback){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8880a8284d28 ((wq_completion)writeback){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8880a8284d28 ((wq_completion)writeback){+.+.}, at: set_work_data kernel/workqueue.c:620 [inline]
#0: ffff8880a8284d28 ((wq_completion)writeback){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8880a8284d28 ((wq_completion)writeback){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2240
#1: ffff8880a988fdc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244
#2: ffff88809b03a0d8 (&type->s_umount_key#32){++++}, at: trylock_super+0x22/0x110 fs/super.c:418
#3: ffff88809b03c990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 mm/page-writeback.c:2344
1 lock held by khungtaskd/1077:
#0: ffffffff88faba80 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5336
1 lock held by khugepaged/1084:
#0: ffff88809b03c990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 mm/page-writeback.c:2344
1 lock held by rsyslogd/8623:
#0: ffff888098f5d860 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801
2 locks held by getty/8713:
#0: ffff8880a1ca4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8714:
#0: ffff8880a0faf090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8715:
#0: ffff8880a0b1e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f192e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8716:
#0: ffff8880a9486090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f112e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8717:
#0: ffff8880a161a090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f312e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8718:
#0: ffff888095db3090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/8719:
#0: ffff88809b09e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
#1: ffffc90005f092e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
1 lock held by syz-execprog/8740:
#0: ffff8880a657d3e8 (&ei->i_mmap_sem){++++}, at: ext4_filemap_fault+0x7e/0xb2 fs/ext4/inode.c:6291

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1077 Comm: khungtaskd Not tainted 5.4.0-rc4-next-20191024 #0
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+0x172/0x1f0 lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:269 [inline]
watchdog+0xc8f/0x1350 kernel/hung_task.c:353
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc4-next-20191024 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:update_group_capacity+0xa/0x920 kernel/sched/fair.c:7647
Code: e8 0b 84 5b 00 e9 57 fd ff ff 48 8b 7d c8 e8 1d 84 5b 00 e9 49 fe ff ff 0f 1f 84 00 00 00 00 00 48 b8 00 00 00 00 00 fc ff df <55> 48 89 e5 41 57 41 56 49 89 fe 48 83 c7 08 48 89 fa 41 55 48 c1
RSP: 0018:ffff8880ae809878 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffff8880ae809a50 RCX: ffffffff8153db8d
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880a9813000
RBP: ffff8880ae809b20 R08: 1ffff110153038a4 R09: ffffed10153038a5
R10: ffffed10153038a4 R11: ffff8880a981c527 R12: dffffc0000000000
R13: ffff8880a981c520 R14: ffff8880ae809af8 R15: ffff8880ae809c30
FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c420000240 CR3: 00000000a5df3000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
load_balance+0x389/0x2a90 kernel/sched/fair.c:8987
rebalance_domains+0x66a/0xba0 kernel/sched/fair.c:9413
_nohz_idle_balance+0x336/0x3f0 kernel/sched/fair.c:9826
nohz_idle_balance kernel/sched/fair.c:9872 [inline]
run_rebalance_domains+0x1c6/0x2d0 kernel/sched/fair.c:10056
__do_softirq+0x262/0x98c kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x19b/0x1e0 kernel/softirq.c:413
scheduler_ipi+0x38c/0x610 kernel/sched/core.c:2347
smp_reschedule_interrupt+0x78/0x4c0 arch/x86/kernel/smp.c:244
reschedule_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:853
</IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: a8 95 5a fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 84 a7 53 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 74 a7 53 00 fb f4 <c3> 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 be 75 0c fa e8 79
RSP: 0018:ffffffff88e07ce8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02
RAX: 1ffffffff11e643f RBX: ffffffff88e7a1c0 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff88e7aa5c
RBP: ffffffff88e07d18 R08: ffffffff88e7a1c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffffff89c81680 R14: 0000000000000000 R15: 0000000000000000
arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x3b7/0x6e0 kernel/sched/idle.c:263
cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:355
rest_init+0x23b/0x371 init/main.c:451
arch_call_rest_init+0xe/0x1b
start_kernel+0x904/0x943 init/main.c:784
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490
x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:471
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

---
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Next message: Vivien Didelot: "[PATCH net-next 0/7] net: dsa: replace routing tables with a list"
Previous message: Johannes Weiner: "[PATCH] mm: rate-limit allocation failure warnings more aggressively"
Next in thread: Johannes Weiner: "Re: INFO: task hung in mpage_prepare_extent_to_map"
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