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Valentin Schneider 7ea98dfa44 sched/deadline: Add more reschedule cases to prio_changed_dl()
I've been tracking down an issue on a ~5.17ish kernel where:

  CPUx                           CPUy

  <DL task p0 owns an rtmutex M>
  <p0 depletes its runtime, gets throttled>
  <rq switches to the idle task>
				 <DL task p1 blocks on M, boost/replenish p0>
				 <No call to resched_curr() happens here>

  [idle task keeps running here until *something*
   accidentally sets TIF_NEED_RESCHED]

On that kernel, it is quite easy to trigger using rt-tests's deadline_test
[1] with the test running on isolated CPUs (this reduces the chance of
something unrelated setting TIF_NEED_RESCHED on the idle tasks, making the
issue even more obvious as the hung task detector chimes in).

I haven't been able to reproduce this using a mainline kernel, even if I
revert

  2972e3050e ("tracing: Make trace_marker{,_raw} stream-like")

which gets rid of the lock involved in the above test, *but* I cannot
convince myself the issue isn't there from looking at the code.

Make prio_changed_dl() issue a reschedule if the current task isn't a
deadline one. While at it, ensure a reschedule is emitted when a
queued-but-not-current task gets boosted with an earlier deadline that
current's.

[1]: https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20230206140612.701871-1-vschneid@redhat.com
2023-02-11 11:18:10 +01:00
arch sched/clock/x86: Mark sched_clock() noinstr 2023-01-31 15:01:47 +01:00
block block-6.2-2023-01-20 2023-01-20 12:44:41 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto This update includes the following changes: 2022-12-14 12:31:09 -08:00
Documentation Linux 6.2-rc6 2023-01-31 15:01:20 +01:00
drivers cpuidle: Fix poll_idle() noinstr annotation 2023-01-31 15:01:47 +01:00
fs Linux 6.2-rc6 2023-01-31 15:01:20 +01:00
include sched/clock: Make local_clock() noinstr 2023-01-31 15:01:47 +01:00
init Linux 6.2-rc6 2023-01-31 15:01:20 +01:00
io_uring io_uring: always prep_async for drain requests 2023-01-27 06:29:29 -07:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel sched/deadline: Add more reschedule cases to prio_changed_dl() 2023-02-11 11:18:10 +01:00
lib cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG 2023-01-31 15:01:45 +01:00
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mm Linux 6.2-rc6 2023-01-31 15:01:20 +01:00
net net: mctp: mark socks as dead on unhash, prevent re-add 2023-01-25 13:07:37 +00:00
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scripts Fix up more non-executable files marked executable 2023-01-28 11:17:57 -08:00
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usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
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Makefile Linux 6.2-rc6 2023-01-29 13:59:43 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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.

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.