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Date: Mon, 7 Jun 2021 13:28:31 +0200
From: Sean Nyekjaer <sean@...nix.com>
To: Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] clk: fix possible circular locking in
clk_notifier_register()
On 07/06/2021 13.01, Sean Nyekjaer wrote:
> Allocating memory with prepare_lock mutex held makes lockdep unhappy
> when memory pressure makes the system do fs_reclaim on eg. rawnand using
> clk.
>
> Fix this by allocating with GFP_ATOMIC instead of GFP_KERNEL.
>
> [ 462.466020] ======================================================
> [ 462.472211] WARNING: possible circular locking dependency detected
> [ 462.478406] 4.19.128-00489-gffc0949c2231 #2 Not tainted
> [ 462.483641] ------------------------------------------------------
> [ 462.489831] kswapd0/22 is trying to acquire lock:
> [ 462.494553] 882c9532 (&c->commit_sem){++++}, at: make_reservation+0x68/0x41c
> [ 462.501638]
> [ 462.501638] but task is already holding lock:
> [ 462.507483] 11f3c233 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x48
> [ 462.514388]
> [ 462.514388] which lock already depends on the new lock.
> [ 462.514388]
> [ 462.522579]
> [ 462.522579] the existing dependency chain (in reverse order) is:
> [ 462.530073]
> [ 462.530073] -> #4 (fs_reclaim){+.+.}:
> [ 462.535242] fs_reclaim_acquire+0x78/0x88
> [ 462.539792] kmem_cache_alloc_trace+0x34/0x2e8
> [ 462.544775] clk_notifier_register+0x84/0xfc
> [ 462.549586] i2c_imx_probe+0x23c/0x678
> [ 462.553872] platform_drv_probe+0x50/0xa0
> [ 462.558419] really_probe+0x2b8/0x3d8
> [ 462.562617] driver_probe_device+0x64/0x16c
> [ 462.567334] __driver_attach+0x120/0x144
> [ 462.571795] bus_for_each_dev+0x7c/0xc4
> [ 462.576166] driver_attach+0x20/0x28
> [ 462.580276] bus_add_driver+0x174/0x208
> [ 462.584646] driver_register+0x90/0x120
> [ 462.589016] __platform_driver_register+0x38/0x4c
> [ 462.594260] i2c_adap_imx_init+0x18/0x20
> [ 462.598721] do_one_initcall+0x8c/0x32c
> [ 462.603096] kernel_init_freeable+0x300/0x3e4
> [ 462.607993] kernel_init+0x10/0x114
> [ 462.612016] ret_from_fork+0x14/0x20
> [ 462.616124] (null)
> [ 462.618928]
> [ 462.618928] -> #3 (prepare_lock){+.+.}:
> [ 462.624270] __mutex_lock+0x60/0x8dc
> [ 462.628381] mutex_lock_nested+0x24/0x2c
> [ 462.632843] clk_prepare_lock+0x44/0xec
> [ 462.637216] clk_unprepare+0x24/0x34
> [ 462.641327] gpmi_disable_clk+0x2c/0x3c
> [ 462.645697] gpmi_select_chip+0x84/0xa4
> [ 462.650071] nand_read_oob+0x748/0x7b8
> [ 462.654358] part_read_oob+0x40/0x78
> [ 462.658466] mtd_read+0x10c/0x13c
> [ 462.662318] ubi_io_read+0xc8/0x354
> [ 462.666342] ubi_eba_read_leb+0xc8/0x544
> [ 462.670798] ubi_eba_read_leb_sg+0x70/0x170
> [ 462.675514] ubi_leb_read_sg+0x7c/0xbc
> [ 462.679799] ubiblock_do_work+0xcc/0x118
> [ 462.684260] process_one_work+0x2a4/0x744
> [ 462.688805] worker_thread+0x5c/0x554
> [ 462.693004] kthread+0x120/0x160
> [ 462.696767] ret_from_fork+0x14/0x20
> [ 462.700874] (null)
> [ 462.703676]
> [ 462.703676] -> #2 (&le->mutex){++++}:
> [ 462.708842] down_read+0x3c/0x80
> [ 462.712608] ubi_eba_read_leb+0x4c/0x544
> [ 462.717065] ubi_leb_read+0x7c/0xbc
> [ 462.721089] ubifs_leb_read+0x34/0x80
> [ 462.725288] ubifs_read_nnode+0x194/0x208
> [ 462.729831] ubifs_lpt_lookup_dirty+0x1e0/0x294
> [ 462.734899] ubifs_replay_journal+0x48/0x15a8
> [ 462.739789] ubifs_mount+0x104c/0x15f0
> [ 462.744074] mount_fs+0x1c/0xb8
> [ 462.747753] vfs_kern_mount.part.0+0x58/0x148
> [ 462.752648] do_mount+0x6a4/0xec8
> [ 462.756499] ksys_mount+0x90/0xbc
> [ 462.760349] sys_mount+0x1c/0x24
> [ 462.764108] ret_fast_syscall+0x0/0x28
> [ 462.768390] 0xbebcbb38
> [ 462.771367]
> [ 462.771367] -> #1 (&c->lp_mutex){+.+.}:
> [ 462.776705] __mutex_lock+0x60/0x8dc
> [ 462.780818] mutex_lock_nested+0x24/0x2c
> [ 462.785277] ubifs_gc_start_commit+0x28/0x32c
> [ 462.790170] do_commit+0x1cc/0x7e4
> [ 462.794105] ubifs_run_commit+0x98/0xd0
> [ 462.798476] grab_empty_leb+0x60/0x98
> [ 462.802674] ubifs_rcvry_gc_commit+0x10c/0x1d8
> [ 462.807651] ubifs_mount+0x1308/0x15f0
> [ 462.811934] mount_fs+0x1c/0xb8
> [ 462.815610] vfs_kern_mount.part.0+0x58/0x148
> [ 462.820503] do_mount+0x6a4/0xec8
> [ 462.824353] ksys_mount+0x90/0xbc
> [ 462.828201] sys_mount+0x1c/0x24
> [ 462.831962] ret_fast_syscall+0x0/0x28
> [ 462.836243] 0xbebcbb38
> [ 462.839220]
> [ 462.839220] -> #0 (&c->commit_sem){++++}:
> [ 462.844733] lock_acquire+0xd4/0x1f8
> [ 462.848845] down_read+0x3c/0x80
> [ 462.852608] make_reservation+0x68/0x41c
> [ 462.857064] ubifs_jnl_write_data+0x134/0x2b8
> [ 462.861955] do_writepage+0x88/0x210
> [ 462.866063] ubifs_writepage+0x1b8/0x274
> [ 462.870522] shrink_page_list+0x800/0xf68
> [ 462.875065] shrink_inactive_list+0x1b4/0x4f0
> [ 462.879956] shrink_node+0x44c/0x9c0
> [ 462.884063] kswapd+0x3f8/0x928
> [ 462.887741] kthread+0x120/0x160
> [ 462.891504] ret_from_fork+0x14/0x20
> [ 462.895609] (null)
> [ 462.898412]
> [ 462.898412] other info that might help us debug this:
> [ 462.898412]
> [ 462.906428] Chain exists of:
> [ 462.906428] &c->commit_sem --> prepare_lock --> fs_reclaim
> [ 462.906428]
> [ 462.916455] Possible unsafe locking scenario:
> [ 462.916455]
> [ 462.922384] CPU0 CPU1
> [ 462.926923] ---- ----
> [ 462.931459] lock(fs_reclaim);
> [ 462.934613] lock(prepare_lock);
> [ 462.940458] lock(fs_reclaim);
> [ 462.946127] lock(&c->commit_sem);
> [ 462.949628]
> [ 462.949628] *** DEADLOCK ***
> [ 462.949628]
> [ 462.955563] 1 lock held by kswapd0/22:
> [ 462.959322] #0: 11f3c233 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x48
>
> Signed-off-by: Sean Nyekjaer <sean@...nix.com>
> ---
>
> Could have used GPF_NOWAIT, but it seems wrong during memory reclaim.
>
Hi,
Seems like this results in a deadlock another place :/
Does anyone have an idea to whats happening..?
/Sean
[ 1462.362442] ======================================================
[ 1462.368635] WARNING: possible circular locking dependency detected
[ 1462.374829] 4.19.128-00489-gffc0949c2231-dirty #8 Not tainted
[ 1462.380585] ------------------------------------------------------
[ 1462.386776] kswapd0/22 is trying to acquire lock:
[ 1462.391495] 24766f3c (&c->commit_sem){++++}, at: make_reservation+0x68/0x41c
[ 1462.398581]
[ 1462.398581] but task is already holding lock:
[ 1462.404424] d2d78f56 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x48
[ 1462.411330]
[ 1462.411330] which lock already depends on the new lock.
[ 1462.411330]
[ 1462.419521]
[ 1462.419521] the existing dependency chain (in reverse order) is:
[ 1462.427015]
[ 1462.427015] -> #5 (fs_reclaim){+.+.}:
[ 1462.432181] fs_reclaim_acquire+0x78/0x88
[ 1462.436729] __kmalloc+0x48/0x31c
[ 1462.440583] pcpu_mem_zalloc+0x34/0x8c
[ 1462.444871] pcpu_create_chunk+0x20/0x270
[ 1462.449415] pcpu_balance_workfn+0x5dc/0x74c
[ 1462.454224] process_one_work+0x2a4/0x744
[ 1462.458768] worker_thread+0x5c/0x554
[ 1462.462968] kthread+0x120/0x160
[ 1462.466731] ret_from_fork+0x14/0x20
[ 1462.470839] (null)
[ 1462.473643]
[ 1462.473643] -> #4 (pcpu_alloc_mutex){+.+.}:
[ 1462.479334] __mutex_lock+0x60/0x8dc
[ 1462.483447] mutex_lock_killable_nested+0x24/0x30
[ 1462.488686] pcpu_alloc+0x404/0x854
[ 1462.492708] __alloc_percpu+0x18/0x20
[ 1462.496911] init_srcu_struct_fields+0x3e4/0x460
[ 1462.502063] __init_srcu_struct+0x50/0x5c
[ 1462.506609] srcu_init_notifier_head+0x2c/0x54
[ 1462.511593] clk_notifier_register+0x9c/0xfc
[ 1462.516403] i2c_imx_probe+0x23c/0x678
[ 1462.520690] platform_drv_probe+0x50/0xa0
[ 1462.525240] really_probe+0x2b8/0x3d8
[ 1462.529437] driver_probe_device+0x64/0x16c
[ 1462.534157] __driver_attach+0x120/0x144
[ 1462.538617] bus_for_each_dev+0x7c/0xc4
[ 1462.542987] driver_attach+0x20/0x28
[ 1462.547098] bus_add_driver+0x174/0x208
[ 1462.551469] driver_register+0x90/0x120
[ 1462.555836] __platform_driver_register+0x38/0x4c
[ 1462.561082] i2c_adap_imx_init+0x18/0x20
[ 1462.565543] do_one_initcall+0x8c/0x32c
[ 1462.569919] kernel_init_freeable+0x300/0x3e4
[ 1462.574816] kernel_init+0x10/0x114
[ 1462.578838] ret_from_fork+0x14/0x20
[ 1462.582944] (null)
[ 1462.585746]
[ 1462.585746] -> #3 (prepare_lock){+.+.}:
[ 1462.591087] __mutex_lock+0x60/0x8dc
[ 1462.595197] mutex_lock_nested+0x24/0x2c
[ 1462.599655] clk_prepare_lock+0x44/0xec
[ 1462.604027] clk_unprepare+0x24/0x34
[ 1462.608139] gpmi_disable_clk+0x2c/0x3c
[ 1462.612510] gpmi_select_chip+0x84/0xa4
[ 1462.616883] nand_read_oob+0x748/0x7b8
[ 1462.621169] part_read_oob+0x40/0x78
[ 1462.625279] mtd_read+0x10c/0x13c
[ 1462.629131] ubi_io_read+0xc8/0x354
[ 1462.633155] ubi_eba_read_leb+0xc8/0x544
[ 1462.637612] ubi_eba_read_leb_sg+0x70/0x170
[ 1462.642329] ubi_leb_read_sg+0x7c/0xbc
[ 1462.646615] ubiblock_do_work+0xcc/0x118
[ 1462.651073] process_one_work+0x2a4/0x744
[ 1462.655616] worker_thread+0x5c/0x554
[ 1462.659815] kthread+0x120/0x160
[ 1462.663577] ret_from_fork+0x14/0x20
[ 1462.667683] (null)
[ 1462.670483]
[ 1462.670483] -> #2 (&le->mutex){++++}:
[ 1462.675653] down_read+0x3c/0x80
[ 1462.679416] ubi_eba_read_leb+0x4c/0x544
[ 1462.683872] ubi_leb_read+0x7c/0xbc
[ 1462.687896] ubifs_leb_read+0x34/0x80
[ 1462.692093] ubifs_read_node+0x9c/0x268
[ 1462.696465] ubifs_load_znode+0x90/0x4a4
[ 1462.700927] ubifs_lookup_level0+0x1c8/0x214
[ 1462.705733] ubifs_tnc_locate+0x60/0x1f4
[ 1462.710189] ubifs_iget+0x9c/0x554
[ 1462.714125] ubifs_mount+0x1278/0x15f0
[ 1462.718410] mount_fs+0x1c/0xb8
[ 1462.722092] vfs_kern_mount.part.0+0x58/0x148
[ 1462.726988] do_mount+0x6a4/0xec8
[ 1462.730839] ksys_mount+0x90/0xbc
[ 1462.734690] sys_mount+0x1c/0x24
[ 1462.738453] ret_fast_syscall+0x0/0x28
[ 1462.742734] 0xbedf2b38
[ 1462.745710]
[ 1462.745710] -> #1 (&c->tnc_mutex){+.+.}:
[ 1462.751139] __mutex_lock+0x60/0x8dc
[ 1462.755250] mutex_lock_nested+0x24/0x2c
[ 1462.759709] ubifs_tnc_add_nm+0x44/0x268
[ 1462.764165] ubifs_jnl_update+0x508/0x694
[ 1462.768709] ubifs_mkdir+0x1b8/0x25c
[ 1462.772820] vfs_mkdir+0xcc/0x13c
[ 1462.776672] do_mkdirat+0x88/0x118
[ 1462.780606] sys_mkdir+0x1c/0x20
[ 1462.784369] ret_fast_syscall+0x0/0x28
[ 1462.788649] 0xbedf16e4
[ 1462.791624]
[ 1462.791624] -> #0 (&c->commit_sem){++++}:
[ 1462.797136] lock_acquire+0xd4/0x1f8
[ 1462.801247] down_read+0x3c/0x80
[ 1462.805010] make_reservation+0x68/0x41c
[ 1462.809465] ubifs_jnl_write_data+0x134/0x2b8
[ 1462.814356] do_writepage+0x88/0x210
[ 1462.818465] ubifs_writepage+0x1b8/0x274
[ 1462.822923] shrink_page_list+0x800/0xf68
[ 1462.827466] shrink_inactive_list+0x1b4/0x4f0
[ 1462.832354] shrink_node+0x44c/0x9c0
[ 1462.836462] kswapd+0x3f8/0x928
[ 1462.840140] kthread+0x120/0x160
[ 1462.843903] ret_from_fork+0x14/0x20
[ 1462.848008] (null)
[ 1462.850810]
[ 1462.850810] other info that might help us debug this:
[ 1462.850810]
[ 1462.858827] Chain exists of:
[ 1462.858827] &c->commit_sem --> pcpu_alloc_mutex --> fs_reclaim
[ 1462.858827]
[ 1462.869200] Possible unsafe locking scenario:
[ 1462.869200]
[ 1462.875130] CPU0 CPU1
[ 1462.879668] ---- ----
[ 1462.884204] lock(fs_reclaim);
[ 1462.887357] lock(pcpu_alloc_mutex);
[ 1462.893549] lock(fs_reclaim);
[ 1462.899218] lock(&c->commit_sem);
[ 1462.902720]
[ 1462.902720] *** DEADLOCK ***
[ 1462.902720]
[ 1462.908655] 1 lock held by kswapd0/22:
[ 1462.912412] #0: d2d78f56 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x48
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