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Petr Mladek cf9b1106c8 printk/nmi: flush NMI messages on the system panic 
In NMI context, printk() messages are stored into per-CPU buffers to
avoid a possible deadlock.  They are normally flushed to the main ring
buffer via an IRQ work.  But the work is never called when the system
calls panic() in the very same NMI handler.

This patch tries to flush NMI buffers before the crash dump is
generated.  In this case it does not risk a double release and bails out
when the logbuf_lock is already taken.  The aim is to get the messages
into the main ring buffer when possible.  It makes them better
accessible in the vmcore.

Then the patch tries to flush the buffers second time when other CPUs
are down.  It might be more aggressive and reset logbuf_lock.  The aim
is to get the messages available for the consequent kmsg_dump() and
console_flush_on_panic() calls.

The patch causes vprintk_emit() to be called even in NMI context again.
But it is done via printk_deferred() so that the console handling is
skipped.  Consoles use internal locks and we could not prevent a
deadlock easily.  They are explicitly called later when the crash dump
is not generated, see console_flush_on_panic().

Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: David Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Kosina <jkosina@suse.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2016-05-20 17:58:30 -07:00
..
bpf Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-05-18 11:51:59 -07:00
configs kconfig: add xenconfig defconfig helper 2015-06-16 11:04:29 +01:00
debug mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings 2016-02-22 08:51:37 +01:00
events Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-05-17 16:26:30 -07:00
gcov gcov: use within_module() helper. 2015-12-04 22:46:25 +01:00
irq This is the bulk of GPIO changes for kernel cycle v4.7: 2016-05-17 17:39:42 -07:00
livepatch Merge branches 'for-4.7/core', 'for-4.7/livepatching-doc' and 'for-4.7/livepatching-ppc64' into for-linus 2016-05-17 12:06:35 +02:00
locking Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-05-16 14:47:16 -07:00
power PM / Hibernate: Call flush_icache_range() on pages restored in-place 2016-04-28 13:35:48 +01:00
printk printk/nmi: flush NMI messages on the system panic 2016-05-20 17:58:30 -07:00
rcu debugobjects: insulate non-fixup logic related to static obj from fixup callbacks 2016-05-19 19:12:14 -07:00
sched Power management material for v4.7-rc1 2016-05-16 19:17:22 -07:00
time debugobjects: insulate non-fixup logic related to static obj from fixup callbacks 2016-05-19 19:12:14 -07:00
trace powerpc updates for 4.7 2016-05-20 10:12:41 -07:00
.gitignore certs: add .gitignore to stop git nagging about x509_certificate_list 2015-10-21 15:18:35 +01:00
Kconfig.freezer
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Kconfig.hz
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Kconfig.locks locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKS 2015-05-12 09:46:00 +02:00
Kconfig.preempt
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Makefile kernel: add kcov code coverage 2016-03-22 15:36:02 -07:00
acct.c acct: check FMODE_CAN_WRITE 2015-04-11 22:27:55 -04:00
async.c async: export current_is_async() 2015-11-19 17:51:48 +01:00
audit.c Merge branch 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit 2016-05-18 18:46:55 -07:00
audit.h security: Make inode argument of inode_getsecid non-const 2015-12-24 11:09:39 -05:00
audit_fsnotify.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
audit_tree.c audit: cleanup prune_tree_thread 2016-04-04 09:46:47 -04:00
audit_watch.c don't bother with ->d_inode->i_sb - it's always equal to ->d_sb 2016-04-10 17:11:51 -04:00
auditfilter.c audit: Fix typo in comment 2016-02-08 11:25:39 -05:00
auditsc.c Merge branch 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit 2016-05-18 18:46:55 -07:00
backtracetest.c
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bounds.c
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capability.c kernel: conditionally support non-root users, groups and capabilities 2015-04-15 16:35:22 -07:00
cgroup.c cgroup: fix compile warning 2016-05-12 11:05:27 -04:00
cgroup_freezer.c cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends 2015-12-03 10:24:08 -05:00
cgroup_pids.c cgroup_pids: fix a typo. 2015-12-14 14:54:37 -05:00
compat.c compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap() 2015-06-04 23:57:18 +02:00
configs.c
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context_tracking.c context_tracking: Switch to new static_branch API 2015-11-24 09:56:43 +01:00
cpu.c sched/hotplug: Make activate() the last hotplug step 2016-05-06 14:58:25 +02:00
cpu_pm.c kernel/cpu_pm: fix cpu_cluster_pm_exit comment 2015-09-03 02:42:20 +02:00
cpuset.c cpuset: use static key better and convert to new API 2016-05-19 19:12:14 -07:00
crash_dump.c
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cred.c kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
delayacct.c kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
dma.c
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elfcore.c
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exec_domain.c Remove rest of exec domains. 2015-04-12 21:03:31 +02:00
exit.c exit_thread: accept a task parameter to be exited 2016-05-20 17:58:30 -07:00
extable.c kernel/extable.c: remove duplicated include 2015-09-10 13:29:01 -07:00
fork.c fork: free thread in copy_process on failure 2016-05-20 17:58:30 -07:00
freezer.c
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futex.c futex: Acknowledge a new waiter in counter before plist 2016-04-21 11:06:09 +02:00
futex_compat.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-01-20 17:09:18 -08:00
groups.c kernel: conditionally support non-root users, groups and capabilities 2015-04-15 16:35:22 -07:00
hung_task.c kernel/hung_task.c: use timeout diff when timeout is updated 2016-03-22 15:36:02 -07:00
irq_work.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
jump_label.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
kallsyms.c kallsyms: add support for relative offsets in kallsyms address table 2016-03-15 16:55:16 -07:00
kcmp.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-01-20 17:09:18 -08:00
kcov.c kcov: don't profile branches in kcov 2016-04-28 19:34:04 -07:00
kexec.c kexec: set KEXEC_TYPE_CRASH before sanity_check_segment_list() 2016-01-20 17:09:18 -08:00
kexec_core.c printk/nmi: flush NMI messages on the system panic 2016-05-20 17:58:30 -07:00
kexec_file.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-03-17 11:33:45 -07:00
kexec_internal.h kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE 2016-01-20 17:09:18 -08:00
kmod.c kmod: don't run async usermode helper as a child of kworker thread 2015-10-23 17:55:10 +09:00
kprobes.c perf/x86/hw_breakpoints: Disallow kernel breakpoints unless kprobe-safe 2015-08-04 10:16:54 +02:00
ksysfs.c rcu: Remove TINY_RCU bloat from pointless boot parameters 2015-12-07 16:59:37 -08:00
kthread.c kernel/kthread.c:kthread_create_on_node(): clarify documentation 2015-09-04 16:54:41 -07:00
latencytop.c sched/debug: Make schedstats a runtime tunable that is disabled by default 2016-02-09 11:54:23 +01:00
membarrier.c sys_membarrier(): system-wide memory barrier (generic, x86) 2015-09-11 15:21:34 -07:00
memremap.c memremap: add arch specific hook for MEMREMAP_WB mappings 2016-04-04 10:26:41 +02:00
module-internal.h
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module.c module: preserve Elf information for livepatch modules 2016-04-01 15:00:10 +02:00
module_signing.c KEYS: Move the point of trust determination to __key_link() 2016-04-11 22:43:43 +01:00
notifier.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 08:40:25 -07:00
nsproxy.c cgroup: introduce cgroup namespaces 2016-02-16 13:04:58 -05:00
padata.c kernel/padata.c: hide unused functions 2016-05-19 19:12:14 -07:00
panic.c printk/nmi: flush NMI messages on the system panic 2016-05-20 17:58:30 -07:00
params.c Nothing exciting, minor tweaks and cleanups. 2015-11-09 15:53:39 -08:00
pid.c Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-31 15:44:04 -08:00
pid_namespace.c
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profile.c profile: hide unused functions when !CONFIG_PROC_FS 2016-03-22 15:36:02 -07:00
ptrace.c ptrace: change __ptrace_unlink() to clear ->ptrace under ->siglock 2016-03-22 15:36:02 -07:00
range.c
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reboot.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
relay.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
resource.c /proc/iomem: only expose physical resource addresses to privileged users 2016-04-14 12:56:09 -07:00
seccomp.c Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2016-05-19 10:02:26 -07:00
signal.c signals/sigaltstack: Report current flag bits in sigaltstack() 2016-05-04 08:34:14 +02:00
smp.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 13:50:29 -07:00
smpboot.c cpu/hotplug: Unpark smpboot threads from the state machine 2016-03-01 20:36:56 +01:00
smpboot.h cpu/hotplug: Create hotplug threads 2016-03-01 20:36:56 +01:00
softirq.c arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections 2016-03-25 16:37:42 -07:00
stacktrace.c
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stop_machine.c kernel/stop_machine.c: remove CONFIG_SMP dependencies 2016-01-16 11:17:24 -08:00
sys.c timer: convert timer_slack_ns from unsigned long to u64 2016-03-17 15:09:34 -07:00
sys_ni.c vfs: add copy_file_range syscall and vfs helper 2015-12-01 14:00:53 -05:00
sysctl.c mm: /proc/sys/vm/stat_refresh to force vmstat update 2016-05-19 19:12:14 -07:00
sysctl_binary.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-03-22 15:36:02 -07:00
task_work.c task_work: remove fifo ordering guarantee 2015-09-05 13:46:58 -07:00
taskstats.c taskstats: use the libnl API to align nlattr on 64-bit 2016-04-23 20:13:25 -04:00
test_kprobes.c
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torture.c rcutorture: Dump trace buffer upon shutdown 2016-04-21 13:47:04 -07:00
tracepoint.c kernel/...: convert pr_warning to pr_warn 2016-03-22 15:36:02 -07:00
tsacct.c time, acct: Drop irq save & restore from __acct_update_integrals() 2016-02-29 09:53:09 +01:00
uid16.c
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up.c
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user-return-notifier.c
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user.c
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user_namespace.c kernel/*: switch to memdup_user_nul() 2016-01-04 10:27:55 -05:00
utsname.c
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utsname_sysctl.c
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watchdog.c watchdog: don't run proc_watchdog_update if new value is same as old 2016-03-17 15:09:34 -07:00
workqueue.c debugobjects: insulate non-fixup logic related to static obj from fixup callbacks 2016-05-19 19:12:14 -07:00
workqueue_internal.h sched/core: Get rid of 'cpu' argument in wq_worker_sleeping() 2016-03-02 10:28:47 -05:00