[syzbot] [bcachefs?] INFO: task hung in do_truncate (3)

[syzbot] [bcachefs?] INFO: task hung in do_truncate (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    feffde684ac2 Merge tag 'for-6.13-rc1-tag' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=107f48df980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=91c852e3d1d7c1a6
dashboard link: https://syzkaller.appspot.com/bug?extid=effe7da6578cd423f98f
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2efea2e60149/disk-feffde68.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f5331b060319/vmlinux-feffde68.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ffe1099c1fd2/bzImage-feffde68.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+effe7da6578cd423f98f@syzkaller.appspotmail.com

INFO: task syz.0.32:6097 blocked for more than 143 seconds.
      Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.32        state:D stack:18040 pid:6097  tgid:6096  ppid:5826   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x17fb/0x4be0 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6905
 rwsem_down_write_slowpath+0xeee/0x13b0 kernel/locking/rwsem.c:1176
 __down_write_common kernel/locking/rwsem.c:1304 [inline]
 __down_write kernel/locking/rwsem.c:1313 [inline]
 down_write+0x1d7/0x220 kernel/locking/rwsem.c:1578
 inode_lock include/linux/fs.h:818 [inline]
 do_truncate+0x20c/0x310 fs/open.c:63
 handle_truncate fs/namei.c:3449 [inline]
 do_open fs/namei.c:3832 [inline]
 path_openat+0x2e1e/0x3590 fs/namei.c:3987
 do_filp_open+0x27f/0x4e0 fs/namei.c:4014
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1402
 do_sys_open fs/open.c:1417 [inline]
 __do_sys_open fs/open.c:1425 [inline]
 __se_sys_open fs/open.c:1421 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1421
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d3397ff19
RSP: 002b:00007f6d3477f058 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f6d33b45fa0 RCX: 00007f6d3397ff19
RDX: 0000000000000000 RSI: 000000000014927e RDI: 0000000020000300
RBP: 00007f6d339f3986 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6d33b45fa0 R15: 00007ffe48f28138
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e937aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937aa0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744
2 locks held by kworker/u8:7/3010:
 #0: ffff8880b863e758 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:598
 #1: ffffc9000bb87d00 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
 #1: ffffc9000bb87d00 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3310
2 locks held by getty/5580:
 #0: ffff88814d0720a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
2 locks held by syz.0.32/6097:
 #0: ffff8880795aa420 (sb_writers#18){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:515
 #1: ffff8880583808c8 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
 #1: ffff8880583808c8 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: do_truncate+0x20c/0x310 fs/open.c:63
5 locks held by syz.0.32/6129:
 #0: ffff8880795aa420 (sb_writers#18){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:515
 #1: ffff8880583808c8 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
 #1: ffff8880583808c8 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: do_truncate+0x20c/0x310 fs/open.c:63
 #2: ffff888052300a38 (&c->snapshot_create_lock){.+.+}-{4:4}, at: bch2_truncate+0x166/0x2d0 fs/bcachefs/io_misc.c:292
 #3: ffff888052304398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:158 [inline]
 #3: ffff888052304398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:249 [inline]
 #3: ffff888052304398 (&c->btree_trans_barrier){.+.+}-{0:0}, at: __bch2_trans_get+0x7e1/0xd30 fs/bcachefs/btree_iter.c:3228
 #4: ffff8880523266d0 (&c->gc_lock){++++}-{4:4}, at: bch2_btree_update_start+0x682/0x14e0 fs/bcachefs/btree_update_interior.c:1197

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline]
 watchdog+0xff6/0x1040 kernel/hung_task.c:397
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:1 Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: bat_events batadv_purge_orig
RIP: 0010:batadv_purge_orig_ref+0x17f/0x1660 net/batman-adv/originator.c:1295
Code: 98 00 00 00 42 80 3c 30 00 4c 8b 74 24 70 74 0d 4c 89 f7 e8 e3 3d 73 f6 48 8b 54 24 38 48 8b 4c 24 40 48 8d 1c cd 00 00 00 00 <49> 03 1e 49 89 de 49 c1 ee 03 48 b8 00 00 00 00 00 fc ff df 41 80
RSP: 0018:ffffc90000117a40 EFLAGS: 00000246
RAX: 1ffff11004ac1e68 RBX: 0000000000001028 RCX: 0000000000000205
RDX: ffff88802560f348 RSI: 0000000000000400 RDI: 0000000000000000
RBP: ffffc90000117ba0 R08: ffffffff8b93ef65 R09: 1ffffffff203036e
R10: dffffc0000000000 R11: ffffffff8b939a10 R12: ffff88805c3a8ec8
R13: ffffffff8168f006 R14: ffff88802560f340 R15: 0000000002000000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563ee709d680 CR3: 000000000e736000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 batadv_purge_orig+0x19/0x60 net/batman-adv/originator.c:1329
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


---
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Re: [syzbot] [f2fs?] INFO: task hung in do_truncate (3)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    bc3372351d0c Merge tag 'for-6.15-rc3-tag' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=138cdccc580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3bbffc3b5b4301e1
dashboard link: https://syzkaller.appspot.com/bug?extid=effe7da6578cd423f98f
compiler:       Debian clang version 15.0.6, Debian LLD 15.0.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17c8ac70580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6c893a6bd7cc/disk-bc337235.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6c31d81cbcae/vmlinux-bc337235.xz
kernel image: https://storage.googleapis.com/syzbot-assets/acf5d144656b/bzImage-bc337235.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/53b1b110f131/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=16d4f204580000)
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/3185ba5a394f/mount_4.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=14ebe7ac580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+effe7da6578cd423f98f@syzkaller.appspotmail.com

INFO: task syz.9.68:6713 blocked for more than 143 seconds.
      Not tainted 6.15.0-rc3-syzkaller-00019-gbc3372351d0c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.68        state:D stack:27592 pid:6713  tgid:6701  ppid:6519   task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x1b33/0x51f0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 rwsem_down_write_slowpath+0xedd/0x1420 kernel/locking/rwsem.c:1176
 __down_write_common kernel/locking/rwsem.c:1304 [inline]
 __down_write kernel/locking/rwsem.c:1313 [inline]
 down_write+0x1da/0x220 kernel/locking/rwsem.c:1578
 inode_lock include/linux/fs.h:867 [inline]
 do_truncate+0x20e/0x310 fs/open.c:63
 vfs_truncate+0x4a6/0x540 fs/open.c:115
 do_sys_truncate+0xd8/0x190 fs/open.c:138
 __do_sys_truncate fs/open.c:150 [inline]
 __se_sys_truncate fs/open.c:148 [inline]
 __x64_sys_truncate+0x5b/0x70 fs/open.c:148
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6c9918e169
RSP: 002b:00007f6c983dd038 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007f6c993b6080 RCX: 00007f6c9918e169
RDX: 0000000000000000 RSI: 0000000000008001 RDI: 00002000000000c0
RBP: 00007f6c99210a68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f6c993b6080 R15: 00007ffc2675ba78


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [f2fs?] INFO: task hung in do_truncate (3)

[Kane York]

This crash appears to entirely ignore the provided filesystem images and just
does tricky fallocate calls followed by a truncate, so it should be easier than
normal to diagnose.

The cwd is opened with O_DIRECT. (or this is EFAULT because path is nullptr?)

The victim file is created with O_NONBLOCK and O_SYNC; that fd is discarded.

The victim file is opened again with O_SYNC and FALLOC_FL_ZERO_RANGE is called
with a gargantuan size.

The victim file is opened again with O_APPEND (!) and FALLOC_FL_INSERT_RANGE is
called with a modest size.

Truncate is called midway through the just-inserted range.

Annotated calls below.

# https://syzkaller.appspot.com/bug?id=7d29d6d7a773d4f608a33cf6a7593faadb1b5803
# See https://goo.gl/kgGztJ for information about syzkaller reproducers.
#{"threaded":true,"repeat":true,"procs":5,"slowdown":1,"sandbox":"none","sandbox_arg":0,"tun":true,"netdev":true,"resetnet":true,"cgroups":true,"binfmt_misc":true,"close_fds":true,"usb":true,"vhci":true,"wifi":true,"ieee802154":true,"sysctl":true,"swap":true,"tmpdir":true,"segv":true}
# mount file2
syz_mount_image$f2fs(&(0x7f0000000040),
&(0x7f00000000c0)='./file2\x00', 0x0,
&(0x7f0000000300)={[{@noinline_xattr}, {@noinline_dentry},
{@prjjquota={'prjjquota', 0x3d, 'active_logs=4'}}, {@jqfmt_vfsv1},
{@noinline_data}, {@noheap}, {@checkpoint_diasble}, {@fastboot},
{@fsync_mode_strict}, {@discard_unit_section}]}, 0x21, 0x552d,
&(0x7f000000abc0)="$[removed]")
# EBADF
pread64(0xffffffffffffffff, 0x0, 0x0, 0xfff)
# EBADF
openat$cgroup_freezer_state(0xffffffffffffffff, &(0x7f0000000080), 0x2, 0x0)
# openat(AT_FDCWD, nullptr, O_DIRECT, 0)
# EFAULT?
openat$nullb(0xffffffffffffff9c, 0x0, 0x4000, 0x0)
# mount 'bus'
syz_mount_image$ext4(&(0x7f0000000080)='ext4\x00',
&(0x7f00000000c0)='./bus\x00', 0x20081e,
&(0x7f0000000040)={[{@nodelalloc}, {@orlov}, {@auto_da_alloc}]}, 0x1,
0x4ef, &(0x7f00000003c0)="$[removed]")
# open file1
# O_RDWR | O_CREAT | O_NOCTTY | O_NONBLOCK | FASYNC | O_LARGEFILE | O_SYNC
# perm 0500
open(&(0x7f0000000080)='./file1\x00', 0x10b942, 0x140)
# open file1
# O_RDWR | O_CREAT | O_LARGEFILE | O_SYNC
# perm 0210
r0 = open(&(0x7f0000000100)='./file1\x00', 0x109042, 0x88)
# fallocate FALLOC_FL_ZERO_RANGE, offset 0, size 0x7000000
fallocate(r0, 0x10, 0x0, 0x7000000)
# openat(AT_FDCWD) file1
# O_WRONLY | O_CREAT | O_APPEND
# perm 0512
r1 = openat(0xffffffffffffff9c, &(0x7f0000000080)='./file1\x00', 0x441, 0x14a)
# fallocate file1 FALLOC_FL_INSERT_RANGE, offset x4000, size x8000
# EPERM?
fallocate(r1, 0x20, 0x4000, 0x8000)
# truncate file1 size x8001
truncate(&(0x7f00000000c0)='./file1\x00', 0x8001)