Sergey Senozhatsky 8dcf2dbf65 printk: drop in_nmi check from printk_safe_flush_on_panic() ... [ Upstream commit 554755be08 ] 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> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-08-03 07:50:24 +02:00
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Makefile	printk: introduce per-cpu safe_print seq buffer	2017-02-08 11:07:11 +01:00
braille.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
braille.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
console_cmdline.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
internal.h	printk: Use the main logbuf in NMI when logbuf_lock is available	2017-05-19 14:42:19 +02:00
printk.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk	2017-09-07 21:00:52 -07:00
printk_safe.c	printk: drop in_nmi check from printk_safe_flush_on_panic()	2018-08-03 07:50:24 +02:00