linux/include
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
..
acpi More ACPI updates for v4.10-rc1 2016-12-22 10:19:32 -08:00
asm-generic asm-prototypes: Clear any CPP defines before declaring the functions 2017-01-05 12:57:42 +01:00
clocksource
crypto This pull contains one set of changes: a conversion of the crypto DocBook 2016-12-17 16:00:34 -08:00
drm drm/probe-helpers: Drop locking from poll_enable 2017-01-12 20:31:17 +01:00
dt-bindings dt-bindings: mfd: Remove TPS65217 interrupts 2016-12-27 10:06:00 -08:00
keys
kvm KVM: arm64: Access CNTHCTL_EL2 bit fields correctly on VHE systems 2017-01-13 11:19:25 +00:00
linux kernel/watchdog: prevent false hardlockup on overloaded system 2017-01-24 16:26:14 -08:00
math-emu
media [media] cec: pass parent device in register(), not allocate() 2016-11-29 12:07:17 -02:00
memory
misc
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-12-27 16:04:37 -08:00
pcmcia
ras
rdma Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
rxrpc
scsi Merge remote-tracking branch 'mkp-scsi/fixes' into fixes 2017-01-17 17:32:54 -05:00
soc powerpc updates for 4.10 2016-12-16 09:26:42 -08:00
sound Merge remote-tracking branches 'asoc/fix/arizona', 'asoc/fix/dpcm', 'asoc/fix/dwc', 'asoc/fix/fsl-ssi' and 'asoc/fix/hdmi-codec' into asoc-linus 2017-01-10 10:47:50 +00:00
target target: add XCOPY target/segment desc sense codes 2017-01-10 08:40:32 -08:00
trace Merge branch 'for-linus-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2017-01-13 17:40:22 -08:00
uapi bpf: rework prog_digest into prog_tag 2017-01-16 14:03:31 -05:00
video
xen xen: features and fixes for 4.10 rc0 2016-12-13 16:07:55 -08:00
Kbuild