Sergey Senozhatsky
384221cbb9
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 13:37:57 +01:00
bpf: check pending signals while verifying programs
2018-12-21 14:15:21 +01:00
cgroup: Fix dom_cgrp propagation when enabling threaded mode
2018-10-04 13:28:08 -07:00
kconfig: tinyconfig: remove stale stack protector fixups
2018-06-15 07:15:28 +09:00
kdb: Use strscpy with destination buffer size
2018-12-01 09:37:33 +01:00
dma-mapping: fix panic caused by passing empty cma command line argument
2018-11-13 11:08:17 -08:00
uprobes: Fix handle_swbp() vs. unregister() + register() race once more
2018-12-08 12:59:06 +01:00
gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT
2018-06-08 18:56:02 +09:00
genirq: Fix race on spurious interrupt detection
2018-11-13 11:08:48 -08:00
Merge branch 'for-4.19/upstream' into for-linus
2018-08-20 18:33:50 +02:00
locking/qspinlock, x86: Provide liveness guarantee
2018-12-21 14:15:12 +01:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
2018-10-12 12:35:02 +02:00
printk: Fix panic caused by passing log_buf_len to command line
2018-11-13 11:08:48 -08:00
rcu: Make need_resched() respond to urgent RCU-QS needs
2018-12-01 09:37:34 +01:00
sched/pelt: Fix warning and clean up IRQ PELT config
2018-12-19 19:19:49 +01:00
posix-timers: Fix division by zero bug
2018-12-29 13:37:56 +01:00
tracing: Fix memory leak of instance function hash filters
2018-12-19 19:19:52 +01:00
kernel/acct.c: fix the acct->needcheck check in check_free_space()
2018-01-04 16:45:09 -08:00
kernel/async.c: revert "async: simplify lowest_in_progress()"
2018-02-06 18:32:44 -08:00
audit: use ktime_get_coarse_real_ts64() for timestamps
2018-07-17 14:45:08 -04:00
audit: track the owner of the command mutex ourselves
2018-02-23 11:22:22 -05:00
fsnotify: add fsnotify_add_inode_mark() wrappers
2018-05-18 14:58:22 +02:00
\n
2018-08-17 09:41:28 -07:00
audit: fix use-after-free in audit_add_watch
2018-07-18 11:43:36 -04:00
audit: rename FILTER_TYPE to FILTER_EXCLUDE
2018-06-19 10:39:54 -04:00
audit/stable-4.18 PR 20180814
2018-08-15 10:46:54 -07:00
kbuild: fix kernel/bounds.c 'W=1' warning
2018-11-13 11:08:47 -08:00
time: Enable get/put_compat_itimerspec64 always
2018-06-24 14:39:47 +02:00
x86/speculation: Rework SMT state change
2018-12-05 19:32:02 +01:00
kernel/crash_core.c: print timestamp using time64_t
2018-08-22 10:52:47 -07:00
delayacct: Use raw_spinlocks
2018-04-27 14:34:51 +02:00
proc: introduce proc_create_single{,_data}
2018-05-16 07:23:35 +02:00
proc: introduce proc_create_single{,_data}
2018-05-16 07:23:35 +02:00
signal: Pass pid type into group_send_sig_info
2018-07-21 12:57:35 -05:00
extable: Make init_kernel_text() global
2018-02-21 16:54:06 +01:00
bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe
2018-06-21 12:33:19 +02:00
mm: respect arch_dup_mmap() return value
2018-09-04 16:45:02 -07:00
PM / reboot: Eliminate race between reboot and suspend
2018-08-06 12:35:20 +02:00
futex: Cure exit race
2018-12-29 13:37:57 +01:00
kernel: make groups_sort calling a responsibility group_info allocators
2017-12-14 16:00:49 -08:00
kernel/hung_task.c: allow to set checking interval separately from timeout
2018-08-22 10:52:47 -07:00
memremap: split devm_memremap_pages() and memremap() infrastructure
2018-05-15 23:08:33 -07:00
irq/work: Improve the flag definitions
2018-01-08 19:43:15 +01:00
jump_label: Fix typo in warning message
2018-09-10 10:15:48 +02:00
kallsyms, x86: Export addresses of PTI entry trampolines
2018-08-14 19:12:29 -03:00
kconfig: include kernel/Kconfig.preempt from init/Kconfig
2018-08-02 08:06:54 +09:00
kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace
2018-12-17 09:24:41 +01:00
kexec: add call to LSM hook in original kexec_load syscall
2018-07-16 12:31:57 -07:00
kexec: yield to scheduler when loading kimage segments
2018-06-15 07:55:24 +09:00
treewide: Use array_size() in vzalloc()
2018-06-12 16:19:22 -07:00
kprobes: Return error if we fail to reuse kprobe instead of BUG_ON()
2018-11-13 11:08:28 -08:00
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-08-13 11:25:07 -07:00
kbuild: move bin2c back to scripts/ from scripts/basic/
2018-07-18 01:18:05 +09:00
libnvdimm-for-4.19_dax-memory-failure
2018-08-25 18:43:59 -07:00
modsign: log module name in the event of an error
2018-07-02 11:36:17 +02:00
module: use relative references for __ksymtab entries
2018-08-22 10:52:47 -07:00
modsign: log module name in the event of an error
2018-07-02 11:36:17 +02:00
padata: add SPDX identifier
2018-01-05 18:43:00 +11:00
panic: avoid deadlocks in re-entrant console drivers
2018-12-29 13:37:57 +01:00
kernel/params.c: downgrade warning for unsafe parameters
2018-04-11 10:28:37 -07:00
fork: report pid exhaustion correctly
2018-09-20 22:01:11 +02:00
Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2018-04-03 19:15:32 -07:00
ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS
2018-12-05 19:32:03 +01:00
PM / reboot: Eliminate race between reboot and suspend
2018-08-06 12:35:20 +02:00
kernel/relay.c: change return type to vm_fault_t
2018-06-15 07:55:24 +09:00
libnvdimm for 4.18
2018-06-08 17:21:52 -07:00
rseq: uapi: Declare rseq_cs field as union, update includes
2018-07-10 22:18:52 +02:00
audit/stable-4.18 PR 20180605
2018-06-06 16:34:00 -07:00
signal: Guard against negative signal numbers in copy_siginfo_from_user32
2018-11-13 11:08:45 -08:00
cpu/hotplug: Fix SMT supported evaluation
2018-08-07 12:25:30 +02:00
smpboot: Remove cpumask from the API
2018-07-03 09:20:44 +02:00
nohz: Fix missing tick reprogram when interrupting an inline softirq
2018-08-03 15:52:10 +02:00
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-08-13 11:25:07 -07:00
kernel/sys.c: remove duplicated include
2018-09-20 22:01:11 +02:00
Merge branch 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-06-10 10:17:09 -07:00
namei: allow restricted O_CREAT of FIFOs and regular files
2018-08-23 18:48:43 -07:00
staging: irda: remove remaining remants of irda code removal
2018-04-16 11:26:49 +02:00
locking/barriers: Convert users of lockless_dereference() to READ_ONCE()
2017-12-17 13:57:15 +01:00
pids: introduce find_get_task_by_vpid() helper
2018-02-06 18:32:46 -08:00
kprobes: Remove jprobe API implementation
2018-06-21 12:33:05 +02:00
torture: Keep old-school dmesg format
2018-06-25 11:30:10 -07:00
tracepoint: Fix tracepoint array element size mismatch
2018-10-17 15:35:29 -04:00
headers: untangle kmemleak.h from mm.h
2018-04-05 21:36:27 -07:00
fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers
2018-04-02 20:15:59 +02:00
kernel: provide ksys_*() wrappers for syscalls called by kernel/uid16.c
2018-04-02 20:15:30 +02:00
umh: fix race condition
2018-06-07 16:56:28 -04:00
userns: use irqsave variant of refcount_dec_and_lock()
2018-08-22 10:52:47 -07:00
userns: also map extents in the reverse map to kernel IDs
2018-11-13 11:09:00 -08:00
uts: create "struct uts_namespace" from kmem_cache
2018-04-11 10:28:35 -07:00
sys: don't hold uts_sem while accessing userspace memory
2018-08-11 02:05:53 -05:00
watchdog: Mark watchdog touch functions as notrace
2018-08-30 12:56:40 +02:00
watchdog: Mark watchdog touch functions as notrace
2018-08-30 12:56:40 +02:00
watchdog: Mark watchdog touch functions as notrace
2018-08-30 12:56:40 +02:00
workqueue: Set worker->desc to workqueue name by default
2018-05-18 08:47:13 -07:00
384221cbb9