syzbot

IPVS: ftp: loaded support on port[0] = 21
INFO: task syz-executor178:8016 blocked for more than 140 seconds.
      Not tainted 4.14.284-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor178 D28912  8016   7992 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:588 [inline]
 rwsem_down_write_failed+0x343/0x6d0 kernel/locking/rwsem-xadd.c:617
 call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:105
 __down_write arch/x86/include/asm/rwsem.h:126 [inline]
 down_write+0x4f/0x90 kernel/locking/rwsem.c:56
 inode_lock include/linux/fs.h:719 [inline]
 fuse_flush+0x1c7/0x520 fs/fuse/file.c:423
 filp_close+0x9d/0x140 fs/open.c:1158
 __close_fd+0x151/0x230 fs/file.c:639
 SYSC_close fs/open.c:1177 [inline]
 SyS_close+0x42/0x90 fs/open.c:1175
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f9499f53a4b
RSP: 002b:00007ffd91fdfb90 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007f9499f53a4b
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 0000000000091eca R08: 0000000000000000 R09: 0000000000000008
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f949a0244dc
R13: 00007ffd91fdfbf0 R14: 0000000000000032 R15: 00007f949a0244c0
INFO: task syz-executor178:8017 blocked for more than 140 seconds.
      Not tainted 4.14.284-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor178 D28464  8017   7992 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2811 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3387
 schedule+0x8d/0x1b0 kernel/sched/core.c:3431
 fuse_wait_on_page_writeback fs/fuse/file.c:385 [inline]
 fuse_wait_on_page_writeback.isra.0+0xdc/0x120 fs/fuse/file.c:381
 fuse_launder_page fs/fuse/file.c:2042 [inline]
 fuse_launder_page+0xa2/0xd0 fs/fuse/file.c:2035
 do_launder_page mm/truncate.c:609 [inline]
 invalidate_inode_pages2_range+0x547/0xc00 mm/truncate.c:685
 fuse_finish_open+0x262/0x500 fs/fuse/file.c:181
 fuse_open_common+0x234/0x290 fs/fuse/file.c:224
 do_dentry_open+0x44b/0xec0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0x628/0x2970 fs/namei.c:3569
 do_filp_open+0x179/0x3c0 fs/namei.c:3603
 do_sys_open+0x296/0x410 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f9499f931c9
RSP: 002b:00007f9499f432f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f949a0244c0 RCX: 00007f9499f931c9
RDX: 0000000000000000 RSI: 0000000000000600 RDI: 0000000020000100
RBP: 00007f9499ff13ac R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 00007f9499fed3a0 R14: 00007f9499fef3a8 R15: 00007f949a0244c8

Showing all locks held in the system:
1 lock held by khungtaskd/1533:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff87028029>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by syz-executor178/8016:
 #0:  (&sb->s_type->i_mutex_key#18){+.+.}, at: [<ffffffff822f41f7>] inode_lock include/linux/fs.h:719 [inline]
 #0:  (&sb->s_type->i_mutex_key#18){+.+.}, at: [<ffffffff822f41f7>] fuse_flush+0x1c7/0x520 fs/fuse/file.c:423
2 locks held by syz-executor178/8017:
 #0:  (sb_writers#10){.+.+}, at: [<ffffffff818e04ca>] sb_start_write include/linux/fs.h:1551 [inline]
 #0:  (sb_writers#10){.+.+}, at: [<ffffffff818e04ca>] mnt_want_write+0x3a/0xb0 fs/namespace.c:386
 #1:  (&sb->s_type->i_mutex_key#18){+.+.}, at: [<ffffffff822f3e04>] inode_lock include/linux/fs.h:719 [inline]
 #1:  (&sb->s_type->i_mutex_key#18){+.+.}, at: [<ffffffff822f3e04>] fuse_open_common+0x1a4/0x290 fs/fuse/file.c:217

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

NMI backtrace for cpu 0
CPU: 0 PID: 1533 Comm: khungtaskd Not tainted 4.14.284-syzkaller #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+0x1b2/0x281 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5b9/0xb40 kernel/hung_task.c:274
 kthread+0x30d/0x420 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 0xffffffff872480fe