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Sergey Senozhatsky 554755be08 printk: drop in_nmi check from printk_safe_flush_on_panic()
Drop the in_nmi() check from printk_safe_flush_on_panic()
and attempt to re-init (IOW unlock) locked logbuf spinlock
from panic CPU regardless of its context.

Otherwise, theoretically, we can deadlock on logbuf trying to flush
per-CPU buffers:

  a) Panic CPU is running in non-NMI context
  b) Panic CPU sends out shutdown IPI via reboot vector
  c) Panic CPU fails to stop all remote CPUs
  d) Panic CPU sends out shutdown IPI via NMI vector
     One of the CPUs that we bring down via NMI vector can hold
     logbuf spin lock (theoretically).

Link: http://lkml.kernel.org/r/20180530070350.10131-1-sergey.senozhatsky@gmail.com
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
2018-06-05 13:38:15 +02:00
arch SCSI for-linus on 20180404 2018-04-05 15:05:53 -07:00
block for-4.17/block-20180402 2018-04-05 14:27:02 -07:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-04-04 17:11:08 -07:00
Documentation Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2018-04-05 19:17:50 -07:00
drivers SCSI for-linus on 20180404 2018-04-05 15:05:53 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2018-04-05 19:17:50 -07:00
include Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 2018-04-05 19:53:30 -07:00
init This is the bulk of GPIO changes for the v4.17 kernel cycle: 2018-04-05 09:51:41 -07:00
ipc 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
kernel printk: drop in_nmi check from printk_safe_flush_on_panic() 2018-06-05 13:38:15 +02:00
lib Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 2018-04-05 19:53:30 -07:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm for-4.17/block-20180402 2018-04-05 14:27:02 -07:00
net Chuck Lever did a bunch of work on nfsd tracepoints, on RDMA, and on 2018-04-05 19:15:29 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-04-03 14:04:18 -07:00
scripts RISC-V changes for 4.17 2018-04-04 16:43:47 -07:00
security 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
sound Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2018-04-05 11:56:35 -07:00
tools Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2018-04-05 11:56:35 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt kvm/arm fixes for 4.16, take 2 2018-03-15 21:45:37 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: move include/config/ksym/* to include/ksym/* 2018-03-26 02:01:23 +09:00
.mailmap Merge remote-tracking branch 'spi/topic/samsung' into spi-next 2018-04-02 15:56:32 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild
Kconfig
MAINTAINERS SCSI for-linus on 20180404 2018-04-05 15:05:53 -07:00
Makefile Kconfig updates for v4.17 2018-04-03 16:28:01 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.