Sergey Senozhatsky
6c976b42dc
panic: avoid deadlocks in re-entrant console drivers ...
commit c7c3f05e341a9a2bd1a92993d4f996cfd6e7348e upstream.
From printk()/serial console point of view panic() is special, because
it may force CPU to re-enter printk() or/and serial console driver.
Therefore, some of serial consoles drivers are re-entrant. E.g. 8250:
serial8250_console_write()
{
if (port->sysrq)
locked = 0;
else if (oops_in_progress)
locked = spin_trylock_irqsave(&port->lock, flags);
else
spin_lock_irqsave(&port->lock, flags);
...
}
panic() does set oops_in_progress via bust_spinlocks(1), so in theory
we should be able to re-enter serial console driver from panic():
CPU0
<NMI>
uart_console_write()
serial8250_console_write() // if (oops_in_progress)
// spin_trylock_irqsave()
call_console_drivers()
console_unlock()
console_flush_on_panic()
bust_spinlocks(1) // oops_in_progress++
panic()
<NMI/>
spin_lock_irqsave(&port->lock, flags) // spin_lock_irqsave()
serial8250_console_write()
call_console_drivers()
console_unlock()
printk()
...
However, this does not happen and we deadlock in serial console on
port->lock spinlock. And the problem is that console_flush_on_panic()
called after bust_spinlocks(0):
void panic(const char *fmt, ...)
{
bust_spinlocks(1);
...
bust_spinlocks(0);
console_flush_on_panic();
...
}
bust_spinlocks(0) decrements oops_in_progress, so oops_in_progress
can go back to zero. Thus even re-entrant console drivers will simply
spin on port->lock spinlock. Given that port->lock may already be
locked either by a stopped CPU, or by the very same CPU we execute
panic() on (for instance, NMI panic() on printing CPU) the system
deadlocks and does not reboot.
Fix this by removing bust_spinlocks(0), so oops_in_progress is always
set in panic() now and, thus, re-entrant console drivers will trylock
the port->lock instead of spinning on it forever, when we call them
from console_flush_on_panic().
Link: http://lkml.kernel.org/r/20181025101036.6823-1-sergey.senozhatsky@gmail.com
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Daniel Wang <wonderfly@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: linux-serial@vger.kernel.org
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-12-29 13:40:16 +01:00
bpf: check pending signals while verifying programs
2018-12-21 14:11:38 +01:00
config: android: enable CONFIG_SECCOMP
2016-10-11 15:06:32 -07:00
kdb: use memmove instead of overlapping memcpy
2018-12-08 13:05:05 +01:00
uprobes: Fix handle_swbp() vs. unregister() + register() race once more
2018-12-08 13:05:06 +01:00
gcov: support GCC 7.1
2017-09-02 07:07:53 +02:00
genirq: Fix race on spurious interrupt detection
2018-11-13 11:17:01 -08:00
livepatch/module: make TAINT_LIVEPATCH module-specific
2016-08-26 14:42:08 +02:00
locking/qspinlock, x86: Provide liveness guarantee
2018-12-21 14:11:34 +01:00
PM / sleep: wakeup: Fix build error caused by missing SRCU support
2018-09-09 20:01:23 +02:00
printk: Fix panic caused by passing log_buf_len to command line
2018-11-13 11:17:01 -08:00
rcu: Call touch_nmi_watchdog() while printing stall warnings
2018-05-30 07:50:50 +02:00
sched/core: Allow __sched_setscheduler() in interrupts when PI is not used
2018-12-01 09:44:25 +01:00
timer/debug: Change /proc/timer_list from 0444 to 0400
2018-12-21 14:11:30 +01:00
tracing: Fix memory leak of instance function hash filters
2018-12-21 14:11:31 +01:00
kernel/acct.c: fix the acct->needcheck check in check_free_space()
2018-01-10 09:29:51 +01:00
kernel/async.c: revert "async: simplify lowest_in_progress()"
2018-02-17 13:21:18 +01:00
audit: return on memory error to avoid null pointer dereference
2018-05-30 07:50:49 +02:00
Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit
2016-07-29 17:54:17 -07:00
audit: fix use-after-free in audit_add_watch
2018-09-26 08:36:37 +02:00
audit: allow not equal op for audit by executable
2018-08-03 07:55:25 +02:00
audit: allow not equal op for audit by executable
2018-08-03 07:55:25 +02:00
kbuild: fix kernel/bounds.c 'W=1' warning
2018-11-13 11:16:57 -08:00
ptrace: Capture the ptracer's creds not PT_PTRACE_CAP
2017-01-06 10:40:13 +01:00
cgroup: Fix deadlock in cpu hotplug path
2018-10-13 09:18:56 +02:00
cgroup/pids: remove spurious suspicious RCU usage warning
2017-03-26 13:05:58 +02:00
Revert "x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigation"
2018-11-23 12:57:41 +01:00
sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
2017-10-12 11:51:25 +02:00
cred: Reject inodes with invalid ids in set_create_file_as()
2016-06-30 18:05:09 -05:00
kernel/exit.c: avoid undefined behaviour when calling wait4()
2018-05-19 10:27:01 +02:00
kernel/extable.c: mark core_kernel_text notrace
2017-07-21 07:42:21 +02:00
kthread: Fix use-after-free if kthread fork fails
2018-09-19 22:47:10 +02:00
freezer, oom: check TIF_MEMDIE on the correct task
2016-07-28 16:07:41 -07:00
futex: futex_wake_op, do not fail on invalid op
2018-11-10 07:42:54 -08:00
kernel: make groups_sort calling a responsibility group_info allocators
2018-01-10 09:29:52 +01:00
hung_task: allow hung_task_panic when hung_task_warnings is 0
2016-10-11 15:06:33 -07:00
jump_label: Invoke jump_label_test() via early_initcall()
2017-12-14 09:28:24 +01:00
kcov: ensure irq code sees a valid area
2018-08-03 07:55:12 +02:00
kexec: allow architectures to override boot mapping
2016-08-02 19:35:27 -04:00
objtool, x86: Add several functions and files to the objtool whitelist
2018-06-05 10:28:57 +02:00
kexec: fix double-free when failing to relocate the purgatory
2016-09-01 17:52:01 -07:00
kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()
2018-11-13 11:16:50 -08:00
kexec: add a kexec_crash_loaded() function
2016-08-02 19:35:30 -04:00
kthread, tracing: Don't expose half-written comm when creating kthreads
2018-08-03 07:55:12 +02:00
kernel/watchdog.c: move hardlockup detector to separate file
2017-06-17 06:41:57 +02:00
Fix: Disable sys_membarrier when nohz_full is enabled
2017-03-12 06:41:45 +01:00
mm: Fix devm_memremap_pages() collision handling
2018-02-28 10:18:34 +01:00
module: exclude SHN_UNDEF symbols from kallsyms api
2018-10-03 17:01:48 -07:00
padata: free correct variable
2017-05-20 14:28:40 +02:00
panic: avoid deadlocks in re-entrant console drivers
2018-12-29 13:40:16 +01:00
pidns: disable pid allocation if pid_ns_prepare_proc() is failed in alloc_pid()
2018-04-13 19:47:53 +02:00
pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes
2017-05-25 15:44:38 +02:00
profile: Convert to hotplug state machine
2016-07-15 10:41:42 +02:00
ptrace: Properly initialize ptracer_cred on fork
2017-06-14 15:05:54 +02:00
kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE
2018-05-30 07:50:29 +02:00
resource: fix integer overflow at reallocation
2018-04-24 09:34:09 +02:00
seccomp: Move speculation migitation control to arch code
2018-05-22 16:58:02 +02:00
signal: Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack
2018-12-21 14:11:29 +01:00
cpu/hotplug: Fix SMT supported evaluation
2018-08-15 18:14:53 +02:00
kthread/smpboot: do not park in kthread_create_on_cpu()
2016-10-11 15:06:33 -07:00
Mark HI and TASKLET softirq synchronous
2018-08-15 18:14:42 +02:00
stacktrace, lockdep: Fix address, newline ugliness
2017-02-14 15:25:42 -08:00
stop_machine: Use raw spinlocks
2018-08-03 07:55:24 +02:00
sys: don't hold uts_sem while accessing userspace memory
2018-09-09 20:01:24 +02:00
x86/pkeys: Fix pkeys build breakage for some non-x86 arches
2016-09-13 14:41:36 +02:00
namei: allow restricted O_CREAT of FIFOs and regular files
2018-12-01 09:44:25 +01:00
kernel/sysctl_binary.c: use generic UUID library
2016-05-20 17:58:30 -07:00
task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works
2016-08-02 19:35:02 -04:00
taskstats: fix the length of cgroupstats_cmd_get_policy
2016-11-03 16:55:58 -04:00
torture: Convert torture_shutdown() to hrtimer
2016-08-22 10:01:49 -07:00
tracepoint: Do not warn on ENOMEM
2018-05-09 09:50:20 +02:00
kernel/ucount.c: mark user_header with kmemleak_ignore()
2017-06-17 06:41:51 +02:00
kernel: make groups_sort calling a responsibility group_info allocators
2018-01-10 09:29:52 +01:00
smp: Add function to execute a function synchronously on a CPU
2016-09-05 13:52:39 +02:00
userns: move user access out of the mutex
2018-09-09 20:01:24 +02:00
Merge branch 'nsfs-ioctls' into HEAD
2016-09-22 20:00:36 -05:00
sys: don't hold uts_sem while accessing userspace memory
2018-09-09 20:01:24 +02:00
kernel/watchdog: prevent false hardlockup on overloaded system
2017-06-17 06:41:57 +02:00
kernel/watchdog: prevent false hardlockup on overloaded system
2017-06-17 06:41:57 +02:00
workqueue: use put_device() instead of kfree()
2018-05-30 07:50:36 +02:00
workqueue: Fix NULL pointer dereference
2017-11-15 15:53:17 +01:00
6c976b42dc