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Filename Latest commit message Latest commit date
Sergey Senozhatsky f9e7a38d14 wq: handle VM suspension in stall detection
[ Upstream commit 940d71c6462e8151c78f28e4919aa8882ff2054e ]

If VCPU is suspended (VM suspend) in wq_watchdog_timer_fn() then
once this VCPU resumes it will see the new jiffies value, while it
may take a while before IRQ detects PVCLOCK_GUEST_STOPPED on this
VCPU and updates all the watchdogs via pvclock_touch_watchdogs().
There is a small chance of misreported WQ stalls in the meantime,
because new jiffies is time_after() old 'ts + thresh'.

wq_watchdog_timer_fn()
{
	for_each_pool(pool, pi) {
		if (time_after(jiffies, ts + thresh)) {
			pr_emerg("BUG: workqueue lockup - pool");
		}
	}
}

Save jiffies at the beginning of this function and use that value
for stall detection. If VM gets suspended then we continue using
"old" jiffies value and old WQ touch timestamps. If IRQ at some
point restarts the stall detection cycle (pvclock_touch_watchdogs())
then old jiffies will always be before new 'ts + thresh'.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-06-16 11:59:35 +02:00
arch x86/kvm: Disable all PV features on crash 2021-06-10 13:37:16 +02:00
block
certs
crypto
Documentation XArray: add xas_split 2021-06-10 13:37:14 +02:00
drivers net: mdiobus: get rid of a BUG_ON() 2021-06-16 11:59:34 +02:00
fs proc: Track /proc/$pid/attr/ opener mm_struct 2021-06-16 11:59:32 +02:00
include XArray: add xas_split 2021-06-10 13:37:14 +02:00
init pid: take a reference when initializing cad_pid 2021-06-10 13:37:11 +02:00
ipc
kernel wq: handle VM suspension in stall detection 2021-06-16 11:59:35 +02:00
lib lib/lz4: explicitly support in-place decompression 2021-06-10 13:37:16 +02:00
LICENSES
mm mm/filemap: fix storing to a THP shadow entry 2021-06-10 13:37:15 +02:00
net netlink: disable IRQs for netlink_lock_table() 2021-06-16 11:59:34 +02:00
samples samples: vfio-mdev: fix error handing in mdpy_fb_probe() 2021-06-10 13:37:03 +02:00
scripts scripts: switch explicitly to Python 3 2021-05-22 11:38:30 +02:00
security
sound ASoC: sti-sas: add missing MODULE_DEVICE_TABLE 2021-06-16 11:59:33 +02:00
tools perf jevents: Fix getting maximum number of fds 2021-06-03 08:59:08 +02:00
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Makefile Linux 5.4.125 2021-06-10 13:37:17 +02:00
README

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.

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.