INFO: task kworker/u8:17:6107 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:17 state:D stack:16256 pid:6107 tgid:6107 ppid:2 task_flags:0x4248160 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
context_switch kernel/sched/core.c:5360 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7046 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7061
xlog_grant_head_wait+0x453/0xa20 fs/xfs/xfs_log.c:267
xlog_grant_head_check+0x286/0x420 fs/xfs/xfs_log.c:-1
xfs_log_reserve+0x2cc/0x780 fs/xfs/xfs_log.c:437
xfs_trans_reserve fs/xfs/xfs_trans.c:176 [inline]
xfs_trans_alloc+0x29c/0x980 fs/xfs/xfs_trans.c:258
xfs_fs_dirty_inode+0x12f/0x1e0 fs/xfs/xfs_super.c:725
__mark_inode_dirty+0x2e9/0xe10 fs/fs-writeback.c:2527
mark_inode_dirty_sync include/linux/fs.h:2608 [inline]
__writeback_single_inode+0x3a1/0xff0 fs/fs-writeback.c:1705
writeback_sb_inodes+0x6c7/0x1010 fs/fs-writeback.c:1976
wb_writeback+0x43b/0xaf0 fs/fs-writeback.c:2156
wb_do_writeback fs/fs-writeback.c:2303 [inline]
wb_workfn+0x409/0xef0 fs/fs-writeback.c:2343
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
INFO: task syz.3.6983:32441 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.6983 state:D stack:25032 pid:32441 tgid:32438 ppid:31022 task_flags:0x400140 flags:0x00024004
Call Trace:
context_switch kernel/sched/core.c:5360 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7046 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7061
wb_wait_for_completion+0x15f/0x260 fs/fs-writeback.c:216
sync_inodes_sb+0x1bb/0xa10 fs/fs-writeback.c:2834
__iterate_supers+0x13d/0x290 fs/super.c:923
ksys_sync+0x94/0x150 fs/sync.c:102
__ia32_sys_sync+0xe/0x20 fs/sync.c:113
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe10998ebe9
RSP: 002b:00007fe10a74e038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fe109bc5fa0 RCX: 00007fe10998ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe109bc5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe109bc6038 R14: 00007fe109bc5fa0 R15: 00007ffc9d973958
INFO: task syz.9.6981:32449 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.6981 state:D stack:22728 pid:32449 tgid:32448 ppid:9769 task_flags:0x440140 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5360 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7046 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7061
xlog_grant_head_wait+0x453/0xa20 fs/xfs/xfs_log.c:267
xlog_grant_head_check+0x286/0x420 fs/xfs/xfs_log.c:-1
xfs_log_reserve+0x2cc/0x780 fs/xfs/xfs_log.c:437
xfs_trans_reserve fs/xfs/xfs_trans.c:176 [inline]
xfs_trans_alloc+0x29c/0x980 fs/xfs/xfs_trans.c:258
xfs_setattr_size+0x7e2/0xee0 fs/xfs/xfs_iops.c:1055
xfs_vn_setattr+0x258/0x300 fs/xfs/xfs_iops.c:1173
notify_change+0xc1a/0xf40 fs/attr.c:546
do_truncate+0x1a4/0x220 fs/open.c:68
handle_truncate fs/namei.c:3508 [inline]
do_open fs/namei.c:3891 [inline]
path_openat+0x306c/0x3830 fs/namei.c:4046
do_filp_open+0x1fa/0x410 fs/namei.c:4073
do_sys_openat2+0x121/0x1c0 fs/open.c:1435
do_sys_open fs/open.c:1450 [inline]
__do_sys_openat fs/open.c:1466 [inline]
__se_sys_openat fs/open.c:1461 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1461
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f820d78ebe9
RSP: 002b:00007f820e58a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f820d9c5fa0 RCX: 00007f820d78ebe9
RDX: 0000000000082242 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f820d811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000232 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f820d9c6038 R14: 00007f820d9c5fa0 R15: 00007ffde862d048
INFO: task syz.9.6981:32478 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.6981 state:D stack:24008 pid:32478 tgid:32448 ppid:9769 task_flags:0x440140 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5360 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7046 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7061
xlog_grant_head_wait+0x453/0xa20 fs/xfs/xfs_log.c:267
xlog_grant_head_check+0x286/0x420 fs/xfs/xfs_log.c:-1
xfs_log_reserve+0x2cc/0x780 fs/xfs/xfs_log.c:437
xfs_trans_reserve fs/xfs/xfs_trans.c:176 [inline]
xfs_trans_alloc+0x29c/0x980 fs/xfs/xfs_trans.c:258
xfs_trans_alloc_inode+0x13c/0x4a0 fs/xfs/xfs_trans.c:1075
xfs_attr_set+0x7fa/0x1210 fs/xfs/libxfs/xfs_attr.c:1098
xfs_xattr_set+0x14d/0x250 fs/xfs/xfs_xattr.c:186
__vfs_setxattr+0x43c/0x480 fs/xattr.c:200
__vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
vfs_setxattr+0x16b/0x2f0 fs/xattr.c:321
do_setxattr fs/xattr.c:636 [inline]
filename_setxattr+0x274/0x600 fs/xattr.c:665
path_setxattrat+0x364/0x3a0 fs/xattr.c:713
__do_sys_setxattr fs/xattr.c:747 [inline]
__se_sys_setxattr fs/xattr.c:743 [inline]
__x64_sys_setxattr+0xbc/0xe0 fs/xattr.c:743
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f820d78ebe9
RSP: 002b:00007f820e548038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f820d9c6180 RCX: 00007f820d78ebe9
RDX: 0000200000000540 RSI: 00002000000001c0 RDI: 0000200000000140
RBP: 00007f820d811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000ff57 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f820d9c6218 R14: 00007f820d9c6180 R15: 00007ffde862d048
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e33cf20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e33cf20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
#0: ffffffff8e33cf20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5616:
#0: ffff88814de6c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
3 locks held by kworker/u8:17/6107:
#0: ffff88801d28e948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88801d28e948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc90005777ba0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc90005777ba0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffff88807b6f2610 (sb_internal#7){.+.+}-{0:0}, at: xfs_trans_alloc+0xd7/0x980 fs/xfs/xfs_trans.c:256
2 locks held by kworker/u8:18/6108:
2 locks held by syz.3.6983/32441:
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: super_lock+0x2a9/0x3b0 fs/super.c:121
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19f/0xa10 fs/fs-writeback.c:2832
4 locks held by syz.9.6981/32449:
#0: ffff88807b6f2420 (sb_writers#31){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:574
#1: ffff888061306c30 (&sb->s_type->i_mutex_key#38){++++}-{4:4}, at: inode_lock_killable include/linux/fs.h:866 [inline]
#1: ffff888061306c30 (&sb->s_type->i_mutex_key#38){++++}-{4:4}, at: do_truncate+0x171/0x220 fs/open.c:63
#2: ffff888061306dd0 (mapping.invalidate_lock#7){++++}-{4:4}, at: xfs_ilock+0x17c/0x390 fs/xfs/xfs_inode.c:157
#3: ffff88807b6f2610 (sb_internal#7){.+.+}-{0:0}, at: xfs_trans_alloc+0xd7/0x980 fs/xfs/xfs_trans.c:256
3 locks held by syz.9.6981/32478:
#0: ffff88807b6f2420 (sb_writers#31){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:574
#1: ffff8880613037b0 (&sb->s_type->i_mutex_key#38){++++}-{4:4}, at: inode_lock include/linux/fs.h:861 [inline]
#1: ffff8880613037b0 (&sb->s_type->i_mutex_key#38){++++}-{4:4}, at: vfs_setxattr+0x144/0x2f0 fs/xattr.c:320
#2: ffff88807b6f2610 (sb_internal#7){.+.+}-{0:0}, at: xfs_trans_alloc+0xd7/0x980 fs/xfs/xfs_trans.c:256
1 lock held by syz-executor/32645:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3433
2 locks held by syz.5.7057/302:
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: super_lock+0x2a9/0x3b0 fs/super.c:121
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19f/0xa10 fs/fs-writeback.c:2832
2 locks held by syz.8.7225/1037:
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: super_lock+0x2a9/0x3b0 fs/super.c:121
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19f/0xa10 fs/fs-writeback.c:2832
2 locks held by syz.4.7295/1327:
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: super_lock+0x2a9/0x3b0 fs/super.c:121
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19f/0xa10 fs/fs-writeback.c:2832
2 locks held by syz.1.7294/1330:
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
#0: ffff88807b6f20e0 (&type->s_umount_key#94){++++}-{4:4}, at: super_lock+0x2a9/0x3b0 fs/super.c:121
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
#1: ffff888142f3c7d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19f/0xa10 fs/fs-writeback.c:2832
2 locks held by syz.3.7429/1922:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x71c/0xb70 net/core/rtnetlink.c:6952
#1: ffffffff8e3429b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
#1: ffffffff8e3429b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730 kernel/rcu/tree_exp.h:957
1 lock held by syz.6.7430/1926:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x37a/0x1df0 drivers/net/tun.c:3075
1 lock held by syz.6.7430/1927:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3433
3 locks held by syz.6.7430/1928:
#0: ffffffff8f7a4f50 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8f7a4d68 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
#1: ffffffff8f7a4d68 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
#1: ffffffff8f7a4d68 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790 net/netlink/genetlink.c:1209
#2: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: __tipc_nl_compat_doit net/tipc/netlink_compat.c:358 [inline]
#2: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: tipc_nl_compat_doit+0x1fd/0x5f0 net/tipc/netlink_compat.c:393
1 lock held by syz.6.7430/1929:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3433
1 lock held by syz.6.7430/1930:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: dev_ioctl+0x7a4/0x1150 net/core/dev_ioctl.c:823
1 lock held by syz.6.7430/1932:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x71c/0xb70 net/core/rtnetlink.c:6952
1 lock held by syz.6.7430/1934:
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff8f73f848 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x71c/0xb70 net/core/rtnetlink.c:6952
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf60/0xfa0 kernel/hung_task.c:495
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6101 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:rcu_is_watching+0x67/0xb0 kernel/rcu/tree.c:752
Code: 89 f7 e8 bc 68 7d 00 48 c7 c3 98 9f c3 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 8b 03 65 ff 0d 09 0d 1b 11 <74> 11 83 e0 04 c1 e8 02 5b 41 5e 41 5f c3 cc cc cc cc cc e8 91 74
RSP: 0018:ffffc900057579e0 EFLAGS: 00000286
RAX: 000000000323bfdc RBX: ffff8880b8732f98 RCX: 4f660b1eef287b00
RDX: ffff88801e3c0000 RSI: ffffffff8c0371e0 RDI: ffffffff8c0371a0
RBP: ffff888058de4888 R08: 0000000000000000 R09: ffffffff8b4c5892
R10: dffffc0000000000 R11: ffffffff8b4c57c0 R12: dffffc0000000000
R13: ffffffff8b4c5892 R14: ffffffff8dde6dd8 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888125af9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3c124e CR3: 000000000e138000 CR4: 00000000003526f0
Call Trace:
rcu_read_lock include/linux/rcupdate.h:842 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
batadv_nc_worker+0x10c/0x610 net/batman-adv/network-coding.c:719
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
IPVS: sed: UDP 224.0.0.2:0 - no destination available