INFO: task hung in ucma_close

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 01fd1694 Linux 4.14.141
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=177b38c6600000
kernel config: https://syzkaller.appspot.com/x/.config?x=62c9b69e1b2adda9
dashboard link: https://syzkaller.appspot.com/bug?extid=1ea809e97d12761d54a6
compiler: gcc (GCC) 9.0.0 20181231 (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+1ea809...@syzkaller.appspotmail.com

BTRFS error (device loop3): unsupported checksum algorithm 2478
BTRFS error (device loop3): superblock checksum mismatch
EXT4-fs (loop2): VFS: Can't find ext4 filesystem
BTRFS error (device loop3): open_ctree failed
INFO: task syz-executor.0:25521 blocked for more than 140 seconds.
Not tainted 4.14.141 #37
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D28528 25521 6879 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2807 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3383
schedule+0x92/0x1c0 kernel/sched/core.c:3427
schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1721
do_wait_for_common kernel/sched/completion.c:91 [inline]
__wait_for_common kernel/sched/completion.c:112 [inline]
wait_for_common kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
ucma_close+0xf0/0x310 drivers/infiniband/core/ucma.c:1749
__fput+0x275/0x7a0 fs/file_table.c:210
____fput+0x16/0x20 fs/file_table.c:244
task_work_run+0x114/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x1da/0x220 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4bc/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x413561
RSP: 002b:00007fff4efdef70 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000413561
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: 000000006e783fbb R09: 000000006e783fbf
R10: 00007fff4efdf050 R11: 0000000000000293 R12: 000000000075c9a0
R13: 000000000075c9a0 R14: 0000000000761460 R15: ffffffffffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1014:
#0: (tasklist_lock){.+.+}, at: [<ffffffff81486308>]
debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4541
1 lock held by rsyslogd/6707:
#0: (&f->f_pos_lock){+.+.}, at: [<ffffffff8194397b>]
__fdget_pos+0xab/0xd0 fs/file.c:769
2 locks held by getty/6829:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861bf263>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ece6>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6830:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861bf263>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ece6>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6831:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861bf263>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ece6>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6832:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861bf263>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ece6>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6833:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861bf263>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ece6>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6834:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861bf263>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ece6>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6835:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861bf263>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ece6>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 0
CPU: 0 PID: 1014 Comm: khungtaskd Not tainted 4.14.141 #37
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x197 lib/dump_stack.c:53
nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5e7/0xb90 kernel/hung_task.c:274
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff861bfd4e


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 414510bc Linux 4.14.142
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15671ed1600000
kernel config: https://syzkaller.appspot.com/x/.config?x=9aa0b2ccd827f416

dashboard link: https://syzkaller.appspot.com/bug?extid=1ea809e97d12761d54a6
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=151b2599600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=176f97c6600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1ea809...@syzkaller.appspotmail.com

audit: type=1400 audit(1567921354.776:36): avc: denied { map } for
pid=6937 comm="syz-executor259" path="/root/syz-executor259614837"
dev="sda1" ino=1426 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
INFO: task syz-executor259:6937 blocked for more than 140 seconds.
Not tainted 4.14.142 #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

syz-executor259 D28144 6937 6935 0x80000002

Call Trace:
context_switch kernel/sched/core.c:2807 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3383
schedule+0x92/0x1c0 kernel/sched/core.c:3427
schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1721
do_wait_for_common kernel/sched/completion.c:91 [inline]
__wait_for_common kernel/sched/completion.c:112 [inline]
wait_for_common kernel/sched/completion.c:123 [inline]
wait_for_completion+0x27c/0x420 kernel/sched/completion.c:144
ucma_close+0xf0/0x310 drivers/infiniband/core/ucma.c:1749
__fput+0x275/0x7a0 fs/file_table.c:210
____fput+0x16/0x20 fs/file_table.c:244
task_work_run+0x114/0x190 kernel/task_work.c:113

exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x7df/0x2c10 kernel/exit.c:874
do_group_exit+0x111/0x330 kernel/exit.c:977
SYSC_exit_group kernel/exit.c:988 [inline]
SyS_exit_group+0x1d/0x20 kernel/exit.c:986
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43eee8
RSP: 002b:00007ffd4b691e58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043eee8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004be6e8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000401ba0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000

Showing all locks held in the system:

1 lock held by khungtaskd/1012:
#0: (tasklist_lock){.+.+}, at: [<ffffffff81487408>]
debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4541

2 locks held by getty/6913:

#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861c1183>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ff66>]

n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6914:

#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861c1183>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ff66>]

n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6915:

#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861c1183>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ff66>]

n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6916:

#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861c1183>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ff66>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6917:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861c1183>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ff66>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6918:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861c1183>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ff66>]
n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6919:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff861c1183>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8310ff66>]

n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 0

CPU: 0 PID: 1012 Comm: khungtaskd Not tainted 4.14.142 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x138/0x197 lib/dump_stack.c:53
nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5e7/0xb90 kernel/hung_task.c:274
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:

NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff861c1c6e

[syzbot]

syzbot suspects this issue was fixed by commit:

commit ef13017d65b003e35f6dbf3236b5e0d82c65a7a1
Author: Shamir Rabinovitch <shamir.ra...@oracle.com>
Date: Thu Sep 24 09:24:49 2020 +0000

RDMA/ucma: ucma_context reference leak in error path

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1439e2e5500000
start commit: f6e27dbb Linux 4.14.146
git tree: linux-4.14.y
kernel config: https://syzkaller.appspot.com/x/.config?x=cb75afefe94a0801
dashboard link: https://syzkaller.appspot.com/bug?extid=1ea809e97d12761d54a6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1227c229600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12891709600000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: RDMA/ucma: ucma_context reference leak in error path

For information about bisection process see: https://goo.gl/tpsmEJ#bisection