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656d61ce96
printk_ratelimit() invokes ___ratelimit() which may invoke a normal
printk() (pr_warn() in this particular case) to warn about suppressed
output. Given that printk_ratelimit() may be called from anywhere, that
pr_warn() is dangerous - it may end up deadlocking the system. Fix
___ratelimit() by using deferred printk().
Sasha reported the following lockdep error:
: Unregister pv shared memory for cpu 8
: select_fallback_rq: 3 callbacks suppressed
: process 8583 (trinity-c78) no longer affine to cpu8
:
: ======================================================
: WARNING: possible circular locking dependency detected
: 4.14.0-rc2-next-20170927+ #252 Not tainted
: ------------------------------------------------------
: migration/8/62 is trying to acquire lock:
: (&port_lock_key){-.-.}, at: serial8250_console_write()
:
: but task is already holding lock:
: (&rq->lock){-.-.}, at: sched_cpu_dying()
:
: which lock already depends on the new lock.
:
:
: the existing dependency chain (in reverse order) is:
:
: -> #3 (&rq->lock){-.-.}:
: __lock_acquire()
: lock_acquire()
: _raw_spin_lock()
: task_fork_fair()
: sched_fork()
: copy_process.part.31()
: _do_fork()
: kernel_thread()
: rest_init()
: start_kernel()
: x86_64_start_reservations()
: x86_64_start_kernel()
: verify_cpu()
:
: -> #2 (&p->pi_lock){-.-.}:
: __lock_acquire()
: lock_acquire()
: _raw_spin_lock_irqsave()
: try_to_wake_up()
: default_wake_function()
: woken_wake_function()
: __wake_up_common()
: __wake_up_common_lock()
: __wake_up()
: tty_wakeup()
: tty_port_default_wakeup()
: tty_port_tty_wakeup()
: uart_write_wakeup()
: serial8250_tx_chars()
: serial8250_handle_irq.part.25()
: serial8250_default_handle_irq()
: serial8250_interrupt()
: __handle_irq_event_percpu()
: handle_irq_event_percpu()
: handle_irq_event()
: handle_level_irq()
: handle_irq()
: do_IRQ()
: ret_from_intr()
: native_safe_halt()
: default_idle()
: arch_cpu_idle()
: default_idle_call()
: do_idle()
: cpu_startup_entry()
: rest_init()
: start_kernel()
: x86_64_start_reservations()
: x86_64_start_kernel()
: verify_cpu()
:
: -> #1 (&tty->write_wait){-.-.}:
: __lock_acquire()
: lock_acquire()
: _raw_spin_lock_irqsave()
: __wake_up_common_lock()
: __wake_up()
: tty_wakeup()
: tty_port_default_wakeup()
: tty_port_tty_wakeup()
: uart_write_wakeup()
: serial8250_tx_chars()
: serial8250_handle_irq.part.25()
: serial8250_default_handle_irq()
: serial8250_interrupt()
: __handle_irq_event_percpu()
: handle_irq_event_percpu()
: handle_irq_event()
: handle_level_irq()
: handle_irq()
: do_IRQ()
: ret_from_intr()
: native_safe_halt()
: default_idle()
: arch_cpu_idle()
: default_idle_call()
: do_idle()
: cpu_startup_entry()
: rest_init()
: start_kernel()
: x86_64_start_reservations()
: x86_64_start_kernel()
: verify_cpu()
:
: -> #0 (&port_lock_key){-.-.}:
: check_prev_add()
: __lock_acquire()
: lock_acquire()
: _raw_spin_lock_irqsave()
: serial8250_console_write()
: univ8250_console_write()
: console_unlock()
: vprintk_emit()
: vprintk_default()
: vprintk_func()
: printk()
: ___ratelimit()
: __printk_ratelimit()
: select_fallback_rq()
: sched_cpu_dying()
: cpuhp_invoke_callback()
: take_cpu_down()
: multi_cpu_stop()
: cpu_stopper_thread()
: smpboot_thread_fn()
: kthread()
: ret_from_fork()
:
: other info that might help us debug this:
:
: Chain exists of:
: &port_lock_key --> &p->pi_lock --> &rq->lock
:
: Possible unsafe locking scenario:
:
: CPU0 CPU1
: ---- ----
: lock(&rq->lock);
: lock(&p->pi_lock);
: lock(&rq->lock);
: lock(&port_lock_key);
:
: *** DEADLOCK ***
:
: 4 locks held by migration/8/62:
: #0: (&p->pi_lock){-.-.}, at: sched_cpu_dying()
: #1: (&rq->lock){-.-.}, at: sched_cpu_dying()
: #2: (printk_ratelimit_state.lock){....}, at: ___ratelimit()
: #3: (console_lock){+.+.}, at: vprintk_emit()
:
: stack backtrace:
: CPU: 8 PID: 62 Comm: migration/8 Not tainted 4.14.0-rc2-next-20170927+ #252
: Call Trace:
: dump_stack()
: print_circular_bug()
: check_prev_add()
: ? add_lock_to_list.isra.26()
: ? check_usage()
: ? kvm_clock_read()
: ? kvm_sched_clock_read()
: ? sched_clock()
: ? check_preemption_disabled()
: __lock_acquire()
: ? __lock_acquire()
: ? add_lock_to_list.isra.26()
: ? debug_check_no_locks_freed()
: ? memcpy()
: lock_acquire()
: ? serial8250_console_write()
: _raw_spin_lock_irqsave()
: ? serial8250_console_write()
: serial8250_console_write()
: ? serial8250_start_tx()
: ? lock_acquire()
: ? memcpy()
: univ8250_console_write()
: console_unlock()
: ? __down_trylock_console_sem()
: vprintk_emit()
: vprintk_default()
: vprintk_func()
: printk()
: ? show_regs_print_info()
: ? lock_acquire()
: ___ratelimit()
: __printk_ratelimit()
: select_fallback_rq()
: sched_cpu_dying()
: ? sched_cpu_starting()
: ? rcutree_dying_cpu()
: ? sched_cpu_starting()
: cpuhp_invoke_callback()
: ? cpu_disable_common()
: take_cpu_down()
: ? trace_hardirqs_off_caller()
: ? cpuhp_invoke_callback()
: multi_cpu_stop()
: ? __this_cpu_preempt_check()
: ? cpu_stop_queue_work()
: cpu_stopper_thread()
: ? cpu_stop_create()
: smpboot_thread_fn()
: ? sort_range()
: ? schedule()
: ? __kthread_parkme()
: kthread()
: ? sort_range()
: ? kthread_create_on_node()
: ret_from_fork()
: process 9121 (trinity-c78) no longer affine to cpu8
: smpboot: CPU 8 is now offline
Link: http://lkml.kernel.org/r/20170928120405.18273-1-sergey.senozhatsky@gmail.com
Fixes:
|
||
|---|---|---|
| .. | ||
| 842 | ||
| fonts | ||
| lz4 | ||
| lzo | ||
| mpi | ||
| raid6 | ||
| reed_solomon | ||
| xz | ||
| zlib_deflate | ||
| zlib_inflate | ||
| zstd | ||
| .gitignore | ||
| argv_split.c | ||
| asn1_decoder.c | ||
| assoc_array.c | ||
| atomic64_test.c | ||
| atomic64.c | ||
| audit.c | ||
| bcd.c | ||
| bch.c | ||
| bitmap.c | ||
| bitrev.c | ||
| bsearch.c | ||
| btree.c | ||
| bug.c | ||
| build_OID_registry | ||
| bust_spinlocks.c | ||
| chacha20.c | ||
| check_signature.c | ||
| checksum.c | ||
| clz_ctz.c | ||
| clz_tab.c | ||
| cmdline.c | ||
| compat_audit.c | ||
| cordic.c | ||
| cpu_rmap.c | ||
| cpumask.c | ||
| crc4.c | ||
| crc7.c | ||
| crc8.c | ||
| crc16.c | ||
| crc32.c | ||
| crc32defs.h | ||
| crc32test.c | ||
| crc-ccitt.c | ||
| crc-itu-t.c | ||
| crc-t10dif.c | ||
| ctype.c | ||
| debug_info.c | ||
| debug_locks.c | ||
| debugobjects.c | ||
| dec_and_lock.c | ||
| decompress_bunzip2.c | ||
| decompress_inflate.c | ||
| decompress_unlz4.c | ||
| decompress_unlzma.c | ||
| decompress_unlzo.c | ||
| decompress_unxz.c | ||
| decompress.c | ||
| devres.c | ||
| digsig.c | ||
| div64.c | ||
| dma-debug.c | ||
| dma-noop.c | ||
| dma-virt.c | ||
| dump_stack.c | ||
| dynamic_debug.c | ||
| dynamic_queue_limits.c | ||
| earlycpio.c | ||
| errseq.c | ||
| extable.c | ||
| fault-inject.c | ||
| fdt_empty_tree.c | ||
| fdt_ro.c | ||
| fdt_rw.c | ||
| fdt_strerror.c | ||
| fdt_sw.c | ||
| fdt_wip.c | ||
| fdt.c | ||
| find_bit.c | ||
| flex_array.c | ||
| flex_proportions.c | ||
| gcd.c | ||
| gen_crc32table.c | ||
| genalloc.c | ||
| glob.c | ||
| globtest.c | ||
| hexdump.c | ||
| hweight.c | ||
| idr.c | ||
| inflate.c | ||
| int_sqrt.c | ||
| interval_tree_test.c | ||
| interval_tree.c | ||
| iomap_copy.c | ||
| iomap.c | ||
| iommu-common.c | ||
| iommu-helper.c | ||
| ioremap.c | ||
| iov_iter.c | ||
| irq_poll.c | ||
| irq_regs.c | ||
| is_single_threaded.c | ||
| jedec_ddr_data.c | ||
| kasprintf.c | ||
| Kconfig | ||
| Kconfig.debug | ||
| Kconfig.kasan | ||
| Kconfig.kgdb | ||
| Kconfig.kmemcheck | ||
| Kconfig.ubsan | ||
| kfifo.c | ||
| klist.c | ||
| kobject_uevent.c | ||
| kobject.c | ||
| kstrtox.c | ||
| kstrtox.h | ||
| lcm.c | ||
| libcrc32c.c | ||
| list_debug.c | ||
| list_sort.c | ||
| llist.c | ||
| locking-selftest-hardirq.h | ||
| locking-selftest-mutex.h | ||
| locking-selftest-rlock-hardirq.h | ||
| locking-selftest-rlock-softirq.h | ||
| locking-selftest-rlock.h | ||
| locking-selftest-rsem.h | ||
| locking-selftest-rtmutex.h | ||
| locking-selftest-softirq.h | ||
| locking-selftest-spin-hardirq.h | ||
| locking-selftest-spin-softirq.h | ||
| locking-selftest-spin.h | ||
| locking-selftest-wlock-hardirq.h | ||
| locking-selftest-wlock-softirq.h | ||
| locking-selftest-wlock.h | ||
| locking-selftest-wsem.h | ||
| locking-selftest.c | ||
| lockref.c | ||
| lru_cache.c | ||
| Makefile | ||
| memory-notifier-error-inject.c | ||
| memweight.c | ||
| net_utils.c | ||
| netdev-notifier-error-inject.c | ||
| nlattr.c | ||
| nmi_backtrace.c | ||
| nodemask.c | ||
| notifier-error-inject.c | ||
| notifier-error-inject.h | ||
| of-reconfig-notifier-error-inject.c | ||
| oid_registry.c | ||
| once.c | ||
| parman.c | ||
| parser.c | ||
| pci_iomap.c | ||
| percpu_counter.c | ||
| percpu_ida.c | ||
| percpu_test.c | ||
| percpu-refcount.c | ||
| plist.c | ||
| pm-notifier-error-inject.c | ||
| prime_numbers.c | ||
| radix-tree.c | ||
| random32.c | ||
| ratelimit.c | ||
| rational.c | ||
| rbtree_test.c | ||
| rbtree.c | ||
| reciprocal_div.c | ||
| refcount.c | ||
| rhashtable.c | ||
| sbitmap.c | ||
| scatterlist.c | ||
| seq_buf.c | ||
| sg_pool.c | ||
| sg_split.c | ||
| sha1.c | ||
| show_mem.c | ||
| siphash.c | ||
| smp_processor_id.c | ||
| sort.c | ||
| stackdepot.c | ||
| stmp_device.c | ||
| string_helpers.c | ||
| string.c | ||
| strncpy_from_user.c | ||
| strnlen_user.c | ||
| swiotlb.c | ||
| syscall.c | ||
| test_bitmap.c | ||
| test_bpf.c | ||
| test_debug_virtual.c | ||
| test_firmware.c | ||
| test_hash.c | ||
| test_hexdump.c | ||
| test_kasan.c | ||
| test_kmod.c | ||
| test_list_sort.c | ||
| test_module.c | ||
| test_parman.c | ||
| test_printf.c | ||
| test_rhashtable.c | ||
| test_siphash.c | ||
| test_sort.c | ||
| test_static_key_base.c | ||
| test_static_keys.c | ||
| test_sysctl.c | ||
| test_user_copy.c | ||
| test_uuid.c | ||
| test-kstrtox.c | ||
| test-string_helpers.c | ||
| textsearch.c | ||
| timerqueue.c | ||
| ts_bm.c | ||
| ts_fsm.c | ||
| ts_kmp.c | ||
| ubsan.c | ||
| ubsan.h | ||
| ucs2_string.c | ||
| usercopy.c | ||
| uuid.c | ||
| vsprintf.c | ||
| win_minmax.c | ||
| xxhash.c | ||