| Message ID | 20220510113809.80626-2-zhengqi.arch@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] mm: fix missing handler for __GFP_NOWARN | expand |
Hi, LGTM: Acked-by: Jiri Slaby <jirislaby@kernel.org> Minor comments below. On 10. 05. 22, 13:38, Qi Zheng wrote: > The pty_write() invokes kmalloc() which may invoke a normal printk() to > print failure message. This can cause a deadlock in the scenario reported > by syz-bot below: > > CPU0 CPU1 CPU2 > ---- ---- ---- > lock(console_owner); > lock(&port_lock_key); > lock(&port->lock); > lock(&port_lock_key); > lock(&port->lock); > lock(console_owner); > > As commit dbdda842fe96 ("printk: Add console owner and waiter logic to > load balance console writes") said, such deadlock can be prevented by > using printk_deferred() in kmalloc() (which is invoked in the section > guarded by the port->lock). But there are too many printk() on the > kmalloc() path, and kmalloc() can be called from anywhere, so changing > printk() to printk_deferred() is too complicated and inelegant. > > Therefore, this patch chooses to specify __GFP_NOWARN to kmalloc(), so > that printk() will not be called, and this deadlock problem can be avoided. > > Syz-bot reported the following lockdep error: > > ====================================================== > WARNING: possible circular locking dependency detected > 5.4.143-00237-g08ccc19a-dirty #10 Not tainted > ------------------------------------------------------ > syz-executor.4/29420 is trying to acquire lock: > ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline] > ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023 > > but task is already holding lock: > ffff8880119c9158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 drivers/tty/pty.c:120 > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: Maybe trim the stack traces a bit, the commit message is unnecessarily long... > -> #2 (&port->lock){-.-.}-{2:2}: > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 > tty_port_tty_get drivers/tty/tty_port.c:288 [inline] <-- lock(&port->lock); > tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47 > serial8250_tx_chars+0x530/0xa80 drivers/tty/serial/8250/8250_port.c:1767 > serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1854 > serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 [inline] <-- lock(&port_lock_key); > serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1870 > serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126 > __handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156 Stop this trace here and trim the rest? > handle_irq_event_percpu+0x76/0x170 kernel/irq/handle.c:196 > handle_irq_event+0xa1/0x130 kernel/irq/handle.c:213 > handle_edge_irq+0x261/0xd00 kernel/irq/chip.c:833 > generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] > do_IRQ+0xf2/0x2e0 arch/x86/kernel/irq.c:250 > ret_from_intr+0x0/0x19 > native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline] > arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline] > default_idle+0x2c/0x1a0 arch/x86/kernel/process.c:572 > cpuidle_idle_call kernel/sched/idle.c:184 [inline] > do_idle+0x44c/0x590 kernel/sched/idle.c:294 > cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:386 > start_secondary+0x2d1/0x3e0 arch/x86/kernel/smpboot.c:264 > secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 > > -> #1 (&port_lock_key){-.-.}-{2:2}: > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 > serial8250_console_write+0x184/0xa40 drivers/tty/serial/8250/8250_port.c:3198 > <-- lock(&port_lock_key); > call_console_drivers kernel/printk/printk.c:1819 [inline] > console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504 > vprintk_emit+0x1b5/0x470 kernel/printk/printk.c:2024 <-- lock(console_owner); > vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 > printk+0xba/0xed kernel/printk/printk.c:2084 > register_console+0x8b3/0xc10 kernel/printk/printk.c:2829 > univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681 > console_init+0x49d/0x6d3 kernel/printk/printk.c:2915 > start_kernel+0x5e9/0x879 init/main.c:713 > secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 > > -> #0 (console_owner){....}-{0:0}: > check_prev_add kernel/locking/lockdep.c:2600 [inline] > check_prevs_add kernel/locking/lockdep.c:2705 [inline] > validate_chain kernel/locking/lockdep.c:3095 [inline] > __lock_acquire+0x27e6/0x4cc0 kernel/locking/lockdep.c:4200 Delete the above 4 lines? > lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734 > console_trylock_spinning kernel/printk/printk.c:1773 [inline] <-- lock(console_owner); > vprintk_emit+0x307/0x470 kernel/printk/printk.c:2023 > vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 > printk+0xba/0xed kernel/printk/printk.c:2084 > fail_dump lib/fault-inject.c:45 [inline] > should_fail+0x67b/0x7c0 lib/fault-inject.c:144 > __should_failslab+0x152/0x1c0 mm/failslab.c:33 > should_failslab+0x5/0x10 mm/slab_common.c:1224 > slab_pre_alloc_hook mm/slab.h:468 [inline] > slab_alloc_node mm/slub.c:2723 [inline] > slab_alloc mm/slub.c:2807 [inline] > __kmalloc+0x72/0x300 mm/slub.c:3871 > kmalloc include/linux/slab.h:582 [inline] > tty_buffer_alloc+0x23f/0x2a0 drivers/tty/tty_buffer.c:175 > __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:273 > tty_insert_flip_string_fixed_flag+0x93/0x250 drivers/tty/tty_buffer.c:318 > tty_insert_flip_string include/linux/tty_flip.h:37 [inline] > pty_write+0x126/0x1f0 drivers/tty/pty.c:122 <-- lock(&port->lock); > n_tty_write+0xa7a/0xfc0 drivers/tty/n_tty.c:2356 > do_tty_write drivers/tty/tty_io.c:961 [inline] > tty_write+0x512/0x930 drivers/tty/tty_io.c:1045 > __vfs_write+0x76/0x100 fs/read_write.c:494 And stop here? > vfs_write+0x268/0x5c0 fs/read_write.c:558 > ksys_write+0x12d/0x250 fs/read_write.c:611 > do_syscall_64+0xd7/0x380 arch/x86/entry/common.c:291 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > other info that might help us debug this: > > Chain exists of: > console_owner --> &port_lock_key --> &port->lock > > Fixes: b6da31b2c07c ("tty: Fix data race in tty_insert_flip_string_fixed_flag") > Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> > --- > drivers/tty/tty_buffer.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c > index 646510476c30..bfa431a8e690 100644 > --- a/drivers/tty/tty_buffer.c > +++ b/drivers/tty/tty_buffer.c > @@ -175,7 +175,8 @@ static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) > */ > if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit) > return NULL; > - p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); > + p = kmalloc(sizeof(struct tty_buffer) + 2 * size, > + GFP_ATOMIC | __GFP_NOWARN); > if (p == NULL) > return NULL; >
On 2022/5/11 1:57 PM, Jiri Slaby wrote: > Hi, > > LGTM: > Acked-by: Jiri Slaby <jirislaby@kernel.org> Thanks. > > Minor comments below. > > On 10. 05. 22, 13:38, Qi Zheng wrote: >> The pty_write() invokes kmalloc() which may invoke a normal printk() to >> print failure message. This can cause a deadlock in the scenario reported >> by syz-bot below: >> >> CPU0 CPU1 CPU2 >> ---- ---- ---- >> lock(console_owner); >> lock(&port_lock_key); >> lock(&port->lock); >> lock(&port_lock_key); >> lock(&port->lock); >> lock(console_owner); >> >> As commit dbdda842fe96 ("printk: Add console owner and waiter logic to >> load balance console writes") said, such deadlock can be prevented by >> using printk_deferred() in kmalloc() (which is invoked in the section >> guarded by the port->lock). But there are too many printk() on the >> kmalloc() path, and kmalloc() can be called from anywhere, so changing >> printk() to printk_deferred() is too complicated and inelegant. >> >> Therefore, this patch chooses to specify __GFP_NOWARN to kmalloc(), so >> that printk() will not be called, and this deadlock problem can be >> avoided. >> >> Syz-bot reported the following lockdep error: >> >> ====================================================== >> WARNING: possible circular locking dependency detected >> 5.4.143-00237-g08ccc19a-dirty #10 Not tainted >> ------------------------------------------------------ >> syz-executor.4/29420 is trying to acquire lock: >> ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: >> console_trylock_spinning kernel/printk/printk.c:1752 [inline] >> ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: >> vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023 >> >> but task is already holding lock: >> ffff8880119c9158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 >> drivers/tty/pty.c:120 >> >> which lock already depends on the new lock. >> >> the existing dependency chain (in reverse order) is: > > Maybe trim the stack traces a bit, the commit message is unnecessarily > long... Agree, will do. > >> -> #2 (&port->lock){-.-.}-{2:2}: >> __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 >> [inline] >> _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 >> tty_port_tty_get drivers/tty/tty_port.c:288 >> [inline] <-- lock(&port->lock); >> tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47 >> serial8250_tx_chars+0x530/0xa80 >> drivers/tty/serial/8250/8250_port.c:1767 >> serial8250_handle_irq.part.0+0x31f/0x3d0 >> drivers/tty/serial/8250/8250_port.c:1854 >> serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 >> [inline] <-- lock(&port_lock_key); >> serial8250_default_handle_irq+0xb2/0x220 >> drivers/tty/serial/8250/8250_port.c:1870 >> serial8250_interrupt+0xfd/0x200 >> drivers/tty/serial/8250/8250_core.c:126 >> __handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156 > > Stop this trace here and trim the rest? Will do. > >> handle_irq_event_percpu+0x76/0x170 kernel/irq/handle.c:196 >> handle_irq_event+0xa1/0x130 kernel/irq/handle.c:213 >> handle_edge_irq+0x261/0xd00 kernel/irq/chip.c:833 >> generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] >> do_IRQ+0xf2/0x2e0 arch/x86/kernel/irq.c:250 >> ret_from_intr+0x0/0x19 >> native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline] >> arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline] >> default_idle+0x2c/0x1a0 arch/x86/kernel/process.c:572 >> cpuidle_idle_call kernel/sched/idle.c:184 [inline] >> do_idle+0x44c/0x590 kernel/sched/idle.c:294 >> cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:386 >> start_secondary+0x2d1/0x3e0 arch/x86/kernel/smpboot.c:264 >> secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 >> >> -> #1 (&port_lock_key){-.-.}-{2:2}: >> __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 >> [inline] >> _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 >> serial8250_console_write+0x184/0xa40 >> drivers/tty/serial/8250/8250_port.c:3198 >> <-- lock(&port_lock_key); >> call_console_drivers kernel/printk/printk.c:1819 [inline] >> console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504 >> vprintk_emit+0x1b5/0x470 >> kernel/printk/printk.c:2024 <-- lock(console_owner); >> vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 >> printk+0xba/0xed kernel/printk/printk.c:2084 >> register_console+0x8b3/0xc10 kernel/printk/printk.c:2829 >> univ8250_console_init+0x3a/0x46 >> drivers/tty/serial/8250/8250_core.c:681 >> console_init+0x49d/0x6d3 kernel/printk/printk.c:2915 >> start_kernel+0x5e9/0x879 init/main.c:713 >> secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 >> >> -> #0 (console_owner){....}-{0:0}: >> check_prev_add kernel/locking/lockdep.c:2600 [inline] >> check_prevs_add kernel/locking/lockdep.c:2705 [inline] >> validate_chain kernel/locking/lockdep.c:3095 [inline] >> __lock_acquire+0x27e6/0x4cc0 kernel/locking/lockdep.c:4200 > > Delete the above 4 lines? Will do. > >> lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734 >> console_trylock_spinning kernel/printk/printk.c:1773 >> [inline] <-- lock(console_owner); >> vprintk_emit+0x307/0x470 kernel/printk/printk.c:2023 >> vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 >> printk+0xba/0xed kernel/printk/printk.c:2084 >> fail_dump lib/fault-inject.c:45 [inline] >> should_fail+0x67b/0x7c0 lib/fault-inject.c:144 >> __should_failslab+0x152/0x1c0 mm/failslab.c:33 >> should_failslab+0x5/0x10 mm/slab_common.c:1224 >> slab_pre_alloc_hook mm/slab.h:468 [inline] >> slab_alloc_node mm/slub.c:2723 [inline] >> slab_alloc mm/slub.c:2807 [inline] >> __kmalloc+0x72/0x300 mm/slub.c:3871 >> kmalloc include/linux/slab.h:582 [inline] >> tty_buffer_alloc+0x23f/0x2a0 drivers/tty/tty_buffer.c:175 >> __tty_buffer_request_room+0x156/0x2a0 >> drivers/tty/tty_buffer.c:273 >> tty_insert_flip_string_fixed_flag+0x93/0x250 >> drivers/tty/tty_buffer.c:318 >> tty_insert_flip_string include/linux/tty_flip.h:37 [inline] >> pty_write+0x126/0x1f0 drivers/tty/pty.c:122 <-- >> lock(&port->lock); >> n_tty_write+0xa7a/0xfc0 drivers/tty/n_tty.c:2356 >> do_tty_write drivers/tty/tty_io.c:961 [inline] >> tty_write+0x512/0x930 drivers/tty/tty_io.c:1045 >> __vfs_write+0x76/0x100 fs/read_write.c:494 > > And stop here? Will do. > >> vfs_write+0x268/0x5c0 fs/read_write.c:558 >> ksys_write+0x12d/0x250 fs/read_write.c:611 >> do_syscall_64+0xd7/0x380 arch/x86/entry/common.c:291 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> >> other info that might help us debug this: >> >> Chain exists of: >> console_owner --> &port_lock_key --> &port->lock >> >> Fixes: b6da31b2c07c ("tty: Fix data race in >> tty_insert_flip_string_fixed_flag") >> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> >> --- >> drivers/tty/tty_buffer.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c >> index 646510476c30..bfa431a8e690 100644 >> --- a/drivers/tty/tty_buffer.c >> +++ b/drivers/tty/tty_buffer.c >> @@ -175,7 +175,8 @@ static struct tty_buffer *tty_buffer_alloc(struct >> tty_port *port, size_t size) >> */ >> if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit) >> return NULL; >> - p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); >> + p = kmalloc(sizeof(struct tty_buffer) + 2 * size, >> + GFP_ATOMIC | __GFP_NOWARN); >> if (p == NULL) >> return NULL; > >
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 646510476c30..bfa431a8e690 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -175,7 +175,8 @@ static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) */ if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit) return NULL; - p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); + p = kmalloc(sizeof(struct tty_buffer) + 2 * size, + GFP_ATOMIC | __GFP_NOWARN); if (p == NULL) return NULL;
The pty_write() invokes kmalloc() which may invoke a normal printk() to print failure message. This can cause a deadlock in the scenario reported by syz-bot below: CPU0 CPU1 CPU2 ---- ---- ---- lock(console_owner); lock(&port_lock_key); lock(&port->lock); lock(&port_lock_key); lock(&port->lock); lock(console_owner); As commit dbdda842fe96 ("printk: Add console owner and waiter logic to load balance console writes") said, such deadlock can be prevented by using printk_deferred() in kmalloc() (which is invoked in the section guarded by the port->lock). But there are too many printk() on the kmalloc() path, and kmalloc() can be called from anywhere, so changing printk() to printk_deferred() is too complicated and inelegant. Therefore, this patch chooses to specify __GFP_NOWARN to kmalloc(), so that printk() will not be called, and this deadlock problem can be avoided. Syz-bot reported the following lockdep error: ====================================================== WARNING: possible circular locking dependency detected 5.4.143-00237-g08ccc19a-dirty #10 Not tainted ------------------------------------------------------ syz-executor.4/29420 is trying to acquire lock: ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline] ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023 but task is already holding lock: ffff8880119c9158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 drivers/tty/pty.c:120 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&port->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 tty_port_tty_get drivers/tty/tty_port.c:288 [inline] <-- lock(&port->lock); tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47 serial8250_tx_chars+0x530/0xa80 drivers/tty/serial/8250/8250_port.c:1767 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1854 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 [inline] <-- lock(&port_lock_key); serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1870 serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156 handle_irq_event_percpu+0x76/0x170 kernel/irq/handle.c:196 handle_irq_event+0xa1/0x130 kernel/irq/handle.c:213 handle_edge_irq+0x261/0xd00 kernel/irq/chip.c:833 generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] do_IRQ+0xf2/0x2e0 arch/x86/kernel/irq.c:250 ret_from_intr+0x0/0x19 native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline] arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline] default_idle+0x2c/0x1a0 arch/x86/kernel/process.c:572 cpuidle_idle_call kernel/sched/idle.c:184 [inline] do_idle+0x44c/0x590 kernel/sched/idle.c:294 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:386 start_secondary+0x2d1/0x3e0 arch/x86/kernel/smpboot.c:264 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 -> #1 (&port_lock_key){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 serial8250_console_write+0x184/0xa40 drivers/tty/serial/8250/8250_port.c:3198 <-- lock(&port_lock_key); call_console_drivers kernel/printk/printk.c:1819 [inline] console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504 vprintk_emit+0x1b5/0x470 kernel/printk/printk.c:2024 <-- lock(console_owner); vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 printk+0xba/0xed kernel/printk/printk.c:2084 register_console+0x8b3/0xc10 kernel/printk/printk.c:2829 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681 console_init+0x49d/0x6d3 kernel/printk/printk.c:2915 start_kernel+0x5e9/0x879 init/main.c:713 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 -> #0 (console_owner){....}-{0:0}: check_prev_add kernel/locking/lockdep.c:2600 [inline] check_prevs_add kernel/locking/lockdep.c:2705 [inline] validate_chain kernel/locking/lockdep.c:3095 [inline] __lock_acquire+0x27e6/0x4cc0 kernel/locking/lockdep.c:4200 lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734 console_trylock_spinning kernel/printk/printk.c:1773 [inline] <-- lock(console_owner); vprintk_emit+0x307/0x470 kernel/printk/printk.c:2023 vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 printk+0xba/0xed kernel/printk/printk.c:2084 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x67b/0x7c0 lib/fault-inject.c:144 __should_failslab+0x152/0x1c0 mm/failslab.c:33 should_failslab+0x5/0x10 mm/slab_common.c:1224 slab_pre_alloc_hook mm/slab.h:468 [inline] slab_alloc_node mm/slub.c:2723 [inline] slab_alloc mm/slub.c:2807 [inline] __kmalloc+0x72/0x300 mm/slub.c:3871 kmalloc include/linux/slab.h:582 [inline] tty_buffer_alloc+0x23f/0x2a0 drivers/tty/tty_buffer.c:175 __tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:273 tty_insert_flip_string_fixed_flag+0x93/0x250 drivers/tty/tty_buffer.c:318 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0x126/0x1f0 drivers/tty/pty.c:122 <-- lock(&port->lock); n_tty_write+0xa7a/0xfc0 drivers/tty/n_tty.c:2356 do_tty_write drivers/tty/tty_io.c:961 [inline] tty_write+0x512/0x930 drivers/tty/tty_io.c:1045 __vfs_write+0x76/0x100 fs/read_write.c:494 vfs_write+0x268/0x5c0 fs/read_write.c:558 ksys_write+0x12d/0x250 fs/read_write.c:611 do_syscall_64+0xd7/0x380 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: console_owner --> &port_lock_key --> &port->lock Fixes: b6da31b2c07c ("tty: Fix data race in tty_insert_flip_string_fixed_flag") Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> --- drivers/tty/tty_buffer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)