It looks like due to 8683edb7755 (xfs: avoid lockdep false positives in
xfs_trans_alloc), it triggers lockdep in some other ways.
[81388.050050] WARNING: possible circular locking dependency detected
[81388.056272] 4.20.0+ #47 Tainted: G W L
[81388.061182] ------------------------------------------------------
[81388.067402] fsfreeze/64059 is trying to acquire lock:
[81388.072487] 000000004f938084 (fs_reclaim){+.+.}, at:
fs_reclaim_acquire.part.19+0x5/0x30
[81388.080649]
[81388.080649] but task is already holding lock:
[81388.086517] 00000000339e9c6f (sb_internal){++++}, at:
percpu_down_write+0xbb/0x410
[81388.094140]
[81388.094140] which lock already depends on the new lock.
[81388.094140]
[81388.102367]
[81388.102367] the existing dependency chain (in reverse order) is:
[81388.109897]
[81388.109897] -> #1 (sb_internal){++++}:
[81388.115163] __lock_acquire+0x460/0x850
[81388.119549] lock_acquire+0x1e0/0x3f0
[81388.123764] __sb_start_write+0x150/0x1e0
[81388.128437] xfs_trans_alloc+0x49b/0x5e0 [xfs]
[81388.133540] xfs_setfilesize_trans_alloc+0xa6/0x1a0 [xfs]
[81388.139602] xfs_submit_ioend+0x239/0x3e0 [xfs]
[81388.144790] xfs_vm_writepage+0xbc/0x100 [xfs]
[81388.149793] pageout.isra.2+0x919/0x13c0
[81388.154264] shrink_page_list+0x3807/0x58a0
[81388.158997] shrink_inactive_list+0x4b3/0xfc0
[81388.163909] shrink_node_memcg+0x5e5/0x1660
[81388.168642] shrink_node+0x2a3/0xaa0
[81388.172766] balance_pgdat+0x7cc/0xea0
[81388.177067] kswapd+0x65e/0xc40
[81388.180757] kthread+0x1d2/0x1f0
[81388.184535] ret_from_fork+0x27/0x50
[81388.188655]
[81388.188655] -> #0 (fs_reclaim){+.+.}:
[81388.193832] validate_chain.isra.14+0xd43/0x1910
[81388.199004] __lock_acquire+0x460/0x850
[81388.203391] lock_acquire+0x1e0/0x3f0
[81388.207602] fs_reclaim_acquire.part.19+0x29/0x30
[81388.212862] fs_reclaim_acquire+0x19/0x20
[81388.217424] kmem_cache_alloc+0x2f/0x330
[81388.222004] kmem_zone_alloc+0x6e/0x110 [xfs]
[81388.227023] xfs_trans_alloc+0xfd/0x5e0 [xfs]
[81388.232034] xfs_sync_sb+0x76/0x100 [xfs]
[81388.236701] xfs_log_sbcount+0x8e/0xa0 [xfs]
[81388.241631] xfs_quiesce_attr+0x112/0x1d0 [xfs]
[81388.246821] xfs_fs_freeze+0x38/0x50 [xfs]
[81388.251469] freeze_super+0x122/0x190
[81388.255682] do_vfs_ioctl+0xa04/0xbe0
[81388.259894] ksys_ioctl+0x41/0x80
[81388.263758] __x64_sys_ioctl+0x43/0x4c
[81388.268060] do_syscall_64+0x164/0x7ea
[81388.272357] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[81388.277966]
[81388.277966] other info that might help us debug this:
[81388.277966]
[81388.286019] Possible unsafe locking scenario:
[81388.286019]
[81388.291976] CPU0 CPU1
[81388.296537] ---- ----
[81388.301096] lock(sb_internal);
[81388.304346] lock(fs_reclaim);
[81388.310041] lock(sb_internal);
[81388.315822] lock(fs_reclaim);
[81388.318986]
[81388.318986] *** DEADLOCK ***
[81388.318986]
[81388.324942] 4 locks held by fsfreeze/64059:
[81388.329152] #0: 00000000045ba59e (sb_writers#8){++++}, at:
percpu_down_write+0xbb/0x410
[81388.337300] #1: 000000008f513ec0 (&type->s_umount_key#27){++++}, at:
freeze_super+0xa9/0x190
[81388.345882] #2: 000000004ff629d8 (sb_pagefaults){++++}, at:
percpu_down_write+0xbb/0x410
[81388.354115] #3: 00000000339e9c6f (sb_internal){++++}, at:
percpu_down_write+0xbb/0x410
Also this when running in a low-memory situation.
[ 908.284491] WARNING: possible circular locking dependency detected
[ 908.284495] 4.20.0+ #21 Not tainted
[ 908.290717] hardirqs last disabled at (654034): [<ffffffffb3ac4929>]
bad_range+0x169/0x2e0
[ 908.299018] ------------------------------------------------------
[ 908.299022] kswapd0/436 is trying to acquire lock:
[ 908.305246] softirqs last enabled at (651950): [<ffffffffb4400582>]
__do_softirq+0x582/0x96e
[ 908.308743] 000000003f4658a4 (sb_internal){++++}, at:
xfs_trans_alloc+0x45b/0x590 [xfs]
[ 908.317065] softirqs last disabled at (651941): [<ffffffffb38a5e2f>]
irq_exit+0x7f/0xb0
[ 908.323269]
[ 908.323269] but task is already holding lock:
[ 908.323271] 0000000013ffebb0 (fs_reclaim){+.+.}, at:
__fs_reclaim_acquire+0x5/0x30
[ 908.366227]
[ 908.366227] which lock already depends on the new lock.
[ 908.366227]
[ 908.374452]
[ 908.374452] the existing dependency chain (in reverse order) is:
[ 908.381978]
[ 908.381978] -> #1 (fs_reclaim){+.+.}:
[ 908.387154] lock_acquire+0x1b3/0x3c0
[ 908.391361] fs_reclaim_acquire.part.18+0x29/0x30
[ 908.396623] kmem_cache_alloc+0x29/0x320
[ 908.401189] kmem_zone_alloc+0x63/0x100 [xfs]
[ 908.406213] xfs_trans_alloc+0xdf/0x590 [xfs]
[ 908.411249] xfs_sync_sb+0x73/0xf0 [xfs]
[ 908.415813] xfs_quiesce_attr+0xfa/0x1c0 [xfs]
[ 908.420901] xfs_fs_freeze+0x34/0x50 [xfs]
[ 908.425548] freeze_super+0x11c/0x190
[ 908.429760] do_vfs_ioctl+0x91c/0xaf0
[ 908.433969] ksys_ioctl+0x3a/0x70
[ 908.437828] __x64_sys_ioctl+0x3d/0x44
[ 908.442128] do_syscall_64+0x141/0x705
[ 908.446425] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 908.452029]
[ 908.452029] -> #0 (sb_internal){++++}:
[ 908.457288] __lock_acquire+0x46d/0x860
[ 908.461669] lock_acquire+0x1b3/0x3c0
[ 908.465876] __sb_start_write+0x145/0x1d0
[ 908.470533] xfs_trans_alloc+0x45b/0x590 [xfs]
[ 908.475614] xfs_setfilesize_trans_alloc+0xa1/0x190 [xfs]
[ 908.481658] xfs_submit_ioend+0x236/0x3d0 [xfs]
[ 908.486917] xfs_vm_writepage+0xae/0xf0 [xfs]
[ 908.491824] pageout.isra.2+0x86e/0x1230
[ 908.496293] shrink_page_list+0x337b/0x5460
[ 908.501024] shrink_inactive_list+0x45d/0xe80
[ 908.505930] shrink_node_memcg+0x5df/0x15d0
[ 908.510659] shrink_node+0x260/0x950
[ 908.514778] balance_pgdat+0x440/0x7c0
[ 908.519071] kswapd+0x5c0/0xb20
[ 908.522757] kthread+0x1c7/0x1f0
[ 908.526527] ret_from_fork+0x3a/0x50
[ 908.530646]
[ 908.530646] other info that might help us debug this:
[ 908.530646]
[ 908.538698] Possible unsafe locking scenario:
[ 908.538698]
[ 908.544651] CPU0 CPU1
[ 908.549205] ---- ----
[ 908.553760] lock(fs_reclaim);
[ 908.556917] lock(sb_internal);
[ 908.562695] lock(fs_reclaim);
[ 908.568386] lock(sb_internal);
[ 908.571633]
[ 908.571633] *** DEADLOCK ***
[ 908.571633]
[ 908.577591] 1 lock held by kswapd0/436:
[ 908.581450] #0: 0000000013ffebb0 (fs_reclaim){+.+.}, at:
__fs_reclaim_acquire+0x5/0x30
