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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Qian Cai <cai@lca.pw>,
	Lech Perczak <l.perczak@camlintechnologies.com>,
	Theodore Tso <tytso@mit.edu>, Sasha Levin <sashal@kernel.org>,
	Petr Mladek <pmladek@suse.com>,
	John Ogness <john.ogness@linutronix.de>,
	kernel test robot <oliver.sang@intel.com>,
	"Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: [PATCH 4.19 33/62] Revert "Revert "char/random: silence a lockdep splat with printk()""
Date: Wed, 27 Jul 2022 18:10:42 +0200	[thread overview]
Message-ID: <20220727161005.505206431@linuxfoundation.org> (raw)
In-Reply-To: <20220727161004.175638564@linuxfoundation.org>

From: "Jason A. Donenfeld" <Jason@zx2c4.com>

In 2019, Sergey fixed a lockdep splat with 15341b1dd409 ("char/random:
silence a lockdep splat with printk()"), but that got reverted soon
after from 4.19 because back then it apparently caused various problems.
But the issue it was fixing is still there, and more generally, many
patches turning printk() into printk_deferred() have landed since,
making me suspect it's okay to try this out again.

This should fix the following deadlock found by the kernel test robot:

[   18.287691] WARNING: possible circular locking dependency detected
[   18.287692] 4.19.248-00165-g3d1f971aa81f #1 Not tainted
[   18.287693] ------------------------------------------------------
[   18.287712] stop/202 is trying to acquire lock:
[   18.287713] (ptrval) (console_owner){..-.}, at: console_unlock (??:?)
[   18.287717]
[   18.287718] but task is already holding lock:
[   18.287718] (ptrval) (&(&port->lock)->rlock){-...}, at: pty_write (pty.c:?)
[   18.287722]
[   18.287722] which lock already depends on the new lock.
[   18.287723]
[   18.287724]
[   18.287725] the existing dependency chain (in reverse order) is:
[   18.287725]
[   18.287726] -> #2 (&(&port->lock)->rlock){-...}:
[   18.287729] validate_chain+0x84a/0xe00
[   18.287729] __lock_acquire (lockdep.c:?)
[   18.287730] lock_acquire (??:?)
[   18.287731] _raw_spin_lock_irqsave (??:?)
[   18.287732] tty_port_tty_get (??:?)
[   18.287733] tty_port_default_wakeup (tty_port.c:?)
[   18.287734] tty_port_tty_wakeup (??:?)
[   18.287734] uart_write_wakeup (??:?)
[   18.287735] serial8250_tx_chars (??:?)
[   18.287736] serial8250_handle_irq (??:?)
[   18.287737] serial8250_default_handle_irq (8250_port.c:?)
[   18.287738] serial8250_interrupt (8250_core.c:?)
[   18.287738] __handle_irq_event_percpu (??:?)
[   18.287739] handle_irq_event_percpu (??:?)
[   18.287740] handle_irq_event (??:?)
[   18.287741] handle_edge_irq (??:?)
[   18.287742] handle_irq (??:?)
[   18.287742] do_IRQ (??:?)
[   18.287743] common_interrupt (entry_32.o:?)
[   18.287744] _raw_spin_unlock_irqrestore (??:?)
[   18.287745] uart_write (serial_core.c:?)
[   18.287746] process_output_block (n_tty.c:?)
[   18.287747] n_tty_write (n_tty.c:?)
[   18.287747] tty_write (tty_io.c:?)
[   18.287748] __vfs_write (??:?)
[   18.287749] vfs_write (??:?)
[   18.287750] ksys_write (??:?)
[   18.287750] sys_write (??:?)
[   18.287751] do_fast_syscall_32 (??:?)
[   18.287752] entry_SYSENTER_32 (??:?)
[   18.287752]
[   18.287753] -> #1 (&port_lock_key){-.-.}:
[   18.287756]
[   18.287756] -> #0 (console_owner){..-.}:
[   18.287759] check_prevs_add (lockdep.c:?)
[   18.287760] validate_chain+0x84a/0xe00
[   18.287761] __lock_acquire (lockdep.c:?)
[   18.287761] lock_acquire (??:?)
[   18.287762] console_unlock (??:?)
[   18.287763] vprintk_emit (??:?)
[   18.287764] vprintk_default (??:?)
[   18.287764] vprintk_func (??:?)
[   18.287765] printk (??:?)
[   18.287766] get_random_u32 (??:?)
[   18.287767] shuffle_freelist (slub.c:?)
[   18.287767] allocate_slab (slub.c:?)
[   18.287768] new_slab (slub.c:?)
[   18.287769] ___slab_alloc+0x6d0/0xb20
[   18.287770] __slab_alloc+0xd6/0x2e0
[   18.287770] __kmalloc (??:?)
[   18.287771] tty_buffer_alloc (tty_buffer.c:?)
[   18.287772] __tty_buffer_request_room (tty_buffer.c:?)
[   18.287773] tty_insert_flip_string_fixed_flag (??:?)
[   18.287774] pty_write (pty.c:?)
[   18.287775] process_output_block (n_tty.c:?)
[   18.287776] n_tty_write (n_tty.c:?)
[   18.287777] tty_write (tty_io.c:?)
[   18.287778] __vfs_write (??:?)
[   18.287779] vfs_write (??:?)
[   18.287780] ksys_write (??:?)
[   18.287780] sys_write (??:?)
[   18.287781] do_fast_syscall_32 (??:?)
[   18.287782] entry_SYSENTER_32 (??:?)
[   18.287783]
[   18.287783] other info that might help us debug this:
[   18.287784]
[   18.287785] Chain exists of:
[   18.287785]   console_owner --> &port_lock_key --> &(&port->lock)->rlock
[   18.287789]
[   18.287790]  Possible unsafe locking scenario:
[   18.287790]
[   18.287791]        CPU0                    CPU1
[   18.287792]        ----                    ----
[   18.287792]   lock(&(&port->lock)->rlock);
[   18.287794]                                lock(&port_lock_key);
[   18.287814]                                lock(&(&port->lock)->rlock);
[   18.287815]   lock(console_owner);
[   18.287817]
[   18.287818]  *** DEADLOCK ***
[   18.287818]
[   18.287819] 6 locks held by stop/202:
[   18.287820] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read (??:?)
[   18.287823] #1: (ptrval) (&tty->atomic_write_lock){+.+.}, at: tty_write_lock (tty_io.c:?)
[   18.287826] #2: (ptrval) (&o_tty->termios_rwsem/1){++++}, at: n_tty_write (n_tty.c:?)
[   18.287830] #3: (ptrval) (&ldata->output_lock){+.+.}, at: process_output_block (n_tty.c:?)
[   18.287834] #4: (ptrval) (&(&port->lock)->rlock){-...}, at: pty_write (pty.c:?)
[   18.287838] #5: (ptrval) (console_lock){+.+.}, at: console_trylock_spinning (printk.c:?)
[   18.287841]
[   18.287842] stack backtrace:
[   18.287843] CPU: 0 PID: 202 Comm: stop Not tainted 4.19.248-00165-g3d1f971aa81f #1
[   18.287843] Call Trace:
[   18.287844] dump_stack (??:?)
[   18.287845] print_circular_bug.cold+0x78/0x8b
[   18.287846] check_prev_add+0x66a/0xd20
[   18.287847] check_prevs_add (lockdep.c:?)
[   18.287848] validate_chain+0x84a/0xe00
[   18.287848] __lock_acquire (lockdep.c:?)
[   18.287849] lock_acquire (??:?)
[   18.287850] ? console_unlock (??:?)
[   18.287851] console_unlock (??:?)
[   18.287851] ? console_unlock (??:?)
[   18.287852] ? native_save_fl (??:?)
[   18.287853] vprintk_emit (??:?)
[   18.287854] vprintk_default (??:?)
[   18.287855] vprintk_func (??:?)
[   18.287855] printk (??:?)
[   18.287856] get_random_u32 (??:?)
[   18.287857] ? shuffle_freelist (slub.c:?)
[   18.287858] shuffle_freelist (slub.c:?)
[   18.287858] ? page_address (??:?)
[   18.287859] allocate_slab (slub.c:?)
[   18.287860] new_slab (slub.c:?)
[   18.287861] ? pvclock_clocksource_read (??:?)
[   18.287862] ___slab_alloc+0x6d0/0xb20
[   18.287862] ? kvm_sched_clock_read (kvmclock.c:?)
[   18.287863] ? __slab_alloc+0xbc/0x2e0
[   18.287864] ? native_wbinvd (paravirt.c:?)
[   18.287865] __slab_alloc+0xd6/0x2e0
[   18.287865] __kmalloc (??:?)
[   18.287866] ? __lock_acquire (lockdep.c:?)
[   18.287867] ? tty_buffer_alloc (tty_buffer.c:?)
[   18.287868] tty_buffer_alloc (tty_buffer.c:?)
[   18.287869] __tty_buffer_request_room (tty_buffer.c:?)
[   18.287869] tty_insert_flip_string_fixed_flag (??:?)
[   18.287870] pty_write (pty.c:?)
[   18.287871] process_output_block (n_tty.c:?)
[   18.287872] n_tty_write (n_tty.c:?)
[   18.287873] ? print_dl_stats (??:?)
[   18.287874] ? n_tty_ioctl (n_tty.c:?)
[   18.287874] tty_write (tty_io.c:?)
[   18.287875] ? n_tty_ioctl (n_tty.c:?)
[   18.287876] ? tty_write_unlock (tty_io.c:?)
[   18.287877] __vfs_write (??:?)
[   18.287877] vfs_write (??:?)
[   18.287878] ? __fget_light (file.c:?)
[   18.287879] ksys_write (??:?)

Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Lech Perczak <l.perczak@camlintechnologies.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/lkml/Ytz+lo4zRQYG3JUR@xsang-OptiPlex-9020
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/char/random.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -183,8 +183,8 @@ static void __cold process_random_ready_
 
 #define warn_unseeded_randomness() \
 	if (IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) && !crng_ready()) \
-		pr_notice("%s called from %pS with crng_init=%d\n", \
-			  __func__, (void *)_RET_IP_, crng_init)
+		printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", \
+				__func__, (void *)_RET_IP_, crng_init)
 
 
 /*********************************************************************



  parent reply	other threads:[~2022-07-27 16:35 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-27 16:10 [PATCH 4.19 00/62] 4.19.254-rc1 review Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 01/62] riscv: add as-options for modules with assembly compontents Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 02/62] xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 03/62] xfrm: xfrm_policy: fix a possible double xfrm_pols_put() in xfrm_bundle_lookup() Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 04/62] power/reset: arm-versatile: Fix refcount leak in versatile_reboot_probe Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 05/62] pinctrl: ralink: Check for null return of devm_kcalloc Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 06/62] perf/core: Fix data race between perf_event_set_output() and perf_mmap_close() Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 07/62] ip: Fix data-races around sysctl_ip_fwd_use_pmtu Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 08/62] ip: Fix data-races around sysctl_ip_nonlocal_bind Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 09/62] ip: Fix a data-race around sysctl_fwmark_reflect Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 10/62] tcp/dccp: Fix a data-race around sysctl_tcp_fwmark_accept Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 11/62] tcp: Fix data-races around sysctl_tcp_mtu_probing Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 12/62] tcp: Fix a data-race around sysctl_tcp_probe_threshold Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 13/62] tcp: Fix a data-race around sysctl_tcp_probe_interval Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 14/62] i2c: cadence: Change large transfer count reset logic to be unconditional Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 15/62] net: stmmac: fix dma queue left shift overflow issue Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 16/62] net/tls: Fix race in TLS device down flow Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 17/62] igmp: Fix data-races around sysctl_igmp_llm_reports Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 18/62] igmp: Fix a data-race around sysctl_igmp_max_memberships Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 19/62] tcp: Fix data-races around sysctl_tcp_reordering Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 20/62] tcp: Fix data-races around some timeout sysctl knobs Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 21/62] tcp: Fix a data-race around sysctl_tcp_notsent_lowat Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 22/62] tcp: Fix a data-race around sysctl_tcp_tw_reuse Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 23/62] tcp: Fix data-races around sysctl_tcp_fastopen Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 24/62] be2net: Fix buffer overflow in be_get_module_eeprom Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 25/62] tcp: Fix a data-race around sysctl_tcp_early_retrans Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 26/62] tcp: Fix data-races around sysctl_tcp_recovery Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 27/62] tcp: Fix a data-race around sysctl_tcp_thin_linear_timeouts Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 28/62] tcp: Fix data-races around sysctl_tcp_slow_start_after_idle Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 29/62] tcp: Fix a data-race around sysctl_tcp_retrans_collapse Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 30/62] tcp: Fix a data-race around sysctl_tcp_stdurg Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 31/62] tcp: Fix a data-race around sysctl_tcp_rfc1337 Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 32/62] tcp: Fix data-races around sysctl_tcp_max_reordering Greg Kroah-Hartman
2022-07-27 16:10 ` Greg Kroah-Hartman [this message]
2022-07-27 16:10 ` [PATCH 4.19 34/62] mm/mempolicy: fix uninit-value in mpol_rebind_policy() Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 35/62] bpf: Make sure mac_header was set before using it Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 36/62] drm/tilcdc: Remove obsolete crtc_mode_valid() hack Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 37/62] tilcdc: tilcdc_external: fix an incorrect NULL check on list iterator Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 38/62] HID: multitouch: simplify the application retrieval Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 39/62] HID: multitouch: Lenovo X1 Tablet Gen3 trackpoint and buttons Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 40/62] HID: multitouch: add support for the Smart Tech panel Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 41/62] HID: add ALWAYS_POLL quirk to lenovo pixart mouse Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 42/62] dlm: fix pending remove if msg allocation fails Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 43/62] ima: remove the IMA_TEMPLATE Kconfig option Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 44/62] ALSA: memalloc: Align buffer allocations in page size Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 45/62] Bluetooth: Add bt_skb_sendmsg helper Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 46/62] Bluetooth: Add bt_skb_sendmmsg helper Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 47/62] Bluetooth: SCO: Replace use of memcpy_from_msg with bt_skb_sendmsg Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 48/62] Bluetooth: RFCOMM: Replace use of memcpy_from_msg with bt_skb_sendmmsg Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 49/62] Bluetooth: Fix passing NULL to PTR_ERR Greg Kroah-Hartman
2022-07-27 16:10 ` [PATCH 4.19 50/62] Bluetooth: SCO: Fix sco_send_frame returning skb->len Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 51/62] Bluetooth: Fix bt_skb_sendmmsg not allocating partial chunks Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 52/62] serial: mvebu-uart: correctly report configured baudrate value Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 53/62] tty: drivers/tty/, stop using tty_schedule_flip() Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 54/62] tty: the rest, " Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 55/62] tty: drop tty_schedule_flip() Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 56/62] tty: extract tty_flip_buffer_commit() from tty_flip_buffer_push() Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 57/62] tty: use new tty_insert_flip_string_and_push_buffer() in pty_write() Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 58/62] net: usb: ax88179_178a needs FLAG_SEND_ZLP Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 59/62] PCI: hv: Fix multi-MSI to allow more than one MSI vector Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 60/62] PCI: hv: Fix hv_arch_irq_unmask() for multi-MSI Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 61/62] PCI: hv: Reuse existing IRTE allocation in compose_msi_msg() Greg Kroah-Hartman
2022-07-27 16:11 ` [PATCH 4.19 62/62] PCI: hv: Fix interrupt mapping for multi-MSI Greg Kroah-Hartman
2022-07-28  9:42 ` [PATCH 4.19 00/62] 4.19.254-rc1 review Pavel Machek
2022-07-28  9:45 ` Naresh Kamboju
2022-07-28 14:31 ` Sudip Mukherjee (Codethink)
2022-07-28 14:32 ` Jon Hunter
2022-07-28 14:51 ` Shuah Khan
2022-07-28 22:58 ` Guenter Roeck

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