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Filename Latest commit message Latest commit date
Don Zickus b94f51183b kernel/watchdog: prevent false hardlockup on overloaded system
On an overloaded system, it is possible that a change in the watchdog
threshold can be delayed long enough to trigger a false positive.

This can easily be achieved by having a cpu spinning indefinitely on a
task, while another cpu updates watchdog threshold.

What happens is while trying to park the watchdog threads, the hrtimers
on the other cpus trigger and reprogram themselves with the new slower
watchdog threshold.  Meanwhile, the nmi watchdog is still programmed
with the old faster threshold.

Because the one cpu is blocked, it prevents the thread parking on the
other cpus from completing, which is needed to shutdown the nmi watchdog
and reprogram it correctly.  As a result, a false positive from the nmi
watchdog is reported.

Fix this by setting a park_in_progress flag to block all lockups until
the parking is complete.

Fix provided by Ulrich Obergfell.

[akpm@linux-foundation.org: s/park_in_progress/watchdog_park_in_progress/]
Link: http://lkml.kernel.org/r/1481041033-192236-1-git-send-email-dzickus@redhat.com
Signed-off-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-24 16:26:14 -08:00
arch Merge branch 'stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2017-01-23 13:51:59 -08:00
block blk-mq: Remove unused variable 2017-01-18 15:14:15 -07:00
certs
crypto
Documentation spi: Fixes for v4.10 2017-01-20 12:25:11 -08:00
drivers memory_hotplug: make zone_can_shift() return a boolean value 2017-01-24 16:26:14 -08:00
firmware
fs dax: fix build warnings with FS_DAX and !FS_IOMAP 2017-01-24 16:26:14 -08:00
include kernel/watchdog: prevent false hardlockup on overloaded system 2017-01-24 16:26:14 -08:00
init cgroup: move CONFIG_SOCK_CGROUP_DATA to init/Kconfig 2017-01-11 09:47:10 -05:00
ipc
kernel kernel/watchdog: prevent false hardlockup on overloaded system 2017-01-24 16:26:14 -08:00
lib Merge branch 'stable/for-linus-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb 2017-01-17 09:27:50 -08:00
mm mm/huge_memory.c: respect FOLL_FORCE/FOLL_COW for thp 2017-01-24 16:26:14 -08:00
net Three filesystem endianness fixes (one goes back to the 2.6 era, all 2017-01-20 12:15:48 -08:00
samples Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-01-15 11:37:43 -08:00
scripts
security
sound ASoC: Fixes for v4.10 2017-01-11 19:49:27 +01:00
tools virtio, vhost: fixes, cleanups 2017-01-22 12:40:09 -08:00
usr
virt KVM/ARM updates for 4.10-rc4 2017-01-17 15:04:59 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS drm fixes across the board 2017-01-23 13:10:50 -08:00
Makefile Linux 4.10-rc5 2017-01-22 12:54:15 -08:00
README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.