Hello, syzbot found the following issue on: HEAD commit: 2dac75696c6d Add linux-next specific files for 20231018 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=10ed8d75680000 kernel config: https://syzkaller.appspot.com/x/.config?x=6f8545e1ef7a2b66 dashboard link: https://syzkaller.appspot.com/bug?extid=6f75830acb2e4cdc8e50 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=148fed9d680000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1019f523680000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/2375f16ed327/disk-2dac7569.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/c80aee6e2e6c/vmlinux-2dac7569.xz kernel image: https://storage.googleapis.com/syzbot-assets/664dc23b738d/bzImage-2dac7569.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/7a81659a2d58/mount_0.gz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6f75830acb2e4cdc8e50@xxxxxxxxxxxxxxxxxxxxxxxxx INFO: task kworker/u4:11:2872 blocked for more than 143 seconds. Not tainted 6.6.0-rc6-next-20231018-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:11 state:D stack:23520 pid:2872 tgid:2872 ppid:2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-7:0) Call Trace: <TASK> context_switch kernel/sched/core.c:5369 [inline] __schedule+0xee4/0x5a10 kernel/sched/core.c:6680 __schedule_loop kernel/sched/core.c:6757 [inline] schedule+0xe7/0x270 kernel/sched/core.c:6772 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6829 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x969/0x1340 kernel/locking/mutex.c:747 fat_write_inode fs/fat/inode.c:918 [inline] fat_write_inode+0xfc/0x180 fs/fat/inode.c:911 write_inode fs/fs-writeback.c:1456 [inline] __writeback_single_inode+0xa84/0xe60 fs/fs-writeback.c:1673 writeback_sb_inodes+0x5a2/0x1090 fs/fs-writeback.c:1899 __writeback_inodes_wb+0xff/0x2d0 fs/fs-writeback.c:1970 wb_writeback+0x7fe/0xaa0 fs/fs-writeback.c:2077 wb_check_background_flush fs/fs-writeback.c:2147 [inline] wb_do_writeback fs/fs-writeback.c:2235 [inline] wb_workfn+0x86a/0xfd0 fs/fs-writeback.c:2262 process_one_work+0x8a2/0x15e0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 </TASK> Showing all locks held in the system: 1 lock held by khungtaskd/29: #0: ffffffff8cbacbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline] #0: ffffffff8cbacbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline] #0: ffffffff8cbacbe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x75/0x340 kernel/locking/lockdep.c:6613 4 locks held by kworker/u4:11/2872: #0: ffff888142249d38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x78a/0x15e0 kernel/workqueue.c:2605 #1: ffffc9000aeffd80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7f4/0x15e0 kernel/workqueue.c:2606 #2: ffff888018e6c0e0 (&type->s_umount_key#45){++++}-{3:3}, at: super_trylock_shared+0x1e/0xf0 fs/super.c:610 #3: ffff88807b4281d0 (&sbi->s_lock){+.+.}-{3:3}, at: fat_write_inode fs/fat/inode.c:918 [inline] #3: ffff88807b4281d0 (&sbi->s_lock){+.+.}-{3:3}, at: fat_write_inode+0xfc/0x180 fs/fat/inode.c:911 2 locks held by getty/4814: #0: ffff88814b6680a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc900031332f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xfc6/0x1490 drivers/tty/n_tty.c:2201 4 locks held by syz-executor175/5063: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.6.0-rc6-next-20231018-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 nmi_cpu_backtrace+0x277/0x380 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x299/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline] watchdog+0xf87/0x1210 kernel/hung_task.c:379 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 </TASK> Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 5063 Comm: syz-executor175 Not tainted 6.6.0-rc6-next-20231018-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 RIP: 0010:check_wait_context kernel/locking/lockdep.c:4788 [inline] RIP: 0010:__lock_acquire+0x5b2/0x5dc0 kernel/locking/lockdep.c:5086 Code: b8 0a 00 00 41 89 ef 41 83 ef 01 0f 88 79 1f 00 00 49 b8 00 00 00 00 00 fc ff df 49 63 c7 48 8d 04 80 4c 8d a4 c7 e1 0a 00 00 <eb> 12 41 83 ef 01 49 83 ec 28 41 83 ff ff 0f 84 0c 0b 00 00 4d 8d RSP: 0018:ffffc90003a6f3e0 EFLAGS: 00000002 RAX: 000000000000000a RBX: 0000000000000018 RCX: 0000000000000000 RDX: 1ffff1100f6868c7 RSI: 0000000000000001 RDI: ffff88807b433b80 RBP: 0000000000000003 R08: dffffc0000000000 R09: fffffbfff2344fc8 R10: ffffffff91a27e47 R11: 1ffffffff1976fb9 R12: ffff88807b4346b1 R13: ffff88807b4346b8 R14: ffffffff8cbacbe0 R15: 0000000000000002 FS: 00005555556c7380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055f81ca48600 CR3: 0000000077b86000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <NMI> </NMI> <TASK> lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1b2/0x530 kernel/locking/lockdep.c:5718 rcu_lock_acquire include/linux/rcupdate.h:301 [inline] rcu_read_lock include/linux/rcupdate.h:747 [inline] filemap_get_entry+0xdb/0x460 mm/filemap.c:1803 __filemap_get_folio+0x56/0xa90 mm/filemap.c:1851 __find_get_block_slow fs/buffer.c:203 [inline] __find_get_block fs/buffer.c:1406 [inline] __find_get_block+0x170/0xc30 fs/buffer.c:1400 __getblk_slow+0x10c/0x6b0 fs/buffer.c:1134 bdev_getblk+0xad/0xc0 fs/buffer.c:1434 __getblk include/linux/buffer_head.h:358 [inline] sb_getblk include/linux/buffer_head.h:364 [inline] fat_mirror_bhs+0x244/0x5d0 fs/fat/fatent.c:388 fat_alloc_clusters+0xcb2/0xf70 fs/fat/fatent.c:543 fat_alloc_new_dir+0x107/0xc90 fs/fat/dir.c:1144 vfat_mkdir+0x151/0x350 fs/fat/namei_vfat.c:859 vfs_mkdir+0x577/0x820 fs/namei.c:4105 do_mkdirat+0x2fd/0x3a0 fs/namei.c:4128 __do_sys_mkdirat fs/namei.c:4143 [inline] __se_sys_mkdirat fs/namei.c:4141 [inline] __x64_sys_mkdirat+0x115/0x170 fs/namei.c:4141 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7f1b0ce56b59 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc6cb671e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f1b0ce56b59 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 00000000ffffff9c RBP: 00007f1b0ceca5f0 R08: 000000000000024e R09: 00005555556c84c0 R10: 00007ffc6cb670b0 R11: 0000000000000246 R12: 00007ffc6cb67210 R13: 00007ffc6cb67438 R14: 431bde82d7b634db R15: 00007f1b0ce9f03b </TASK> INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.510 msecs --- This report 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 syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the bug is already fixed, let syzbot know by replying with: #syz fix: exact-commit-title 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. If you want to overwrite bug's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the bug is a duplicate of another bug, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
