linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Borislav Petkov <bp@suse.de>,
	Tadeusz Struk <tadeusz.struk@linaro.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: x86-ml <x86@kernel.org>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: [GIT PULL] sched/urgent for 5.17-rc4
Date: Sun, 13 Feb 2022 10:02:22 -0800	[thread overview]
Message-ID: <CAHk-=wiHUWHHcPLCvyXQKf2wbL3L1SOQSGVuCdf-py6QZGnuqQ@mail.gmail.com> (raw)
In-Reply-To: <Ygj7feK+vdtPw6zj@zn.tnic>

On Sun, Feb 13, 2022 at 4:37 AM Borislav Petkov <bp@suse.de> wrote:
>
> Tadeusz Struk (1):
>       sched/fair: Fix fault in reweight_entity

I've pulled this, but this really smells bad to me.

If set_load_weight() can see a process that hasn't even had the
runqueue pointer set yet, then what keeps *others* from the same
thing?

Adding a test like this in set_load_weight() just makes me go "what
makes this function so special"? IOW, why could only that function see
this situation with a missing cfs_rq pointer?

I really get the feeling that this is papering over a serious mistake
in how commit 4ef0c5c6b5ba ("kernel/sched: Fix sched_fork() access an
invalid sched_task_group") now causes fundamental process state to be
initialized too late - when the process is already visible to others.

The setpriority() -> dequeue_load_avg() chain just seems to be one
possible case.

*ANYBODY* that does find_task_by_vpid(who) would seem to be able to
find a task that hasn't actually been fully set up yet, and

Somebody tell me why I'm wrong, and what makes that setpriority thing
so magically special. Please.

                    Linus

  reply	other threads:[~2022-02-13 18:02 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-13 12:37 [GIT PULL] sched/urgent for 5.17-rc4 Borislav Petkov
2022-02-13 18:02 ` Linus Torvalds [this message]
2022-02-14  8:45   ` Peter Zijlstra
2022-02-14  9:16     ` Peter Zijlstra
2022-02-14 19:17       ` Tejun Heo
2022-02-14 19:35         ` Peter Zijlstra
2022-02-14 19:46           ` Tejun Heo
2022-02-17  8:51       ` [PATCH] sched: Fix yet more sched_fork() races Peter Zijlstra
2022-02-17 10:50         ` Dietmar Eggemann
2022-02-17 12:08         ` Zhang Qiao
2022-02-17 17:33         ` Tadeusz Struk
2022-02-18  6:18         ` Zhang Qiao
2022-02-19 10:14       ` [tip: sched/urgent] " tip-bot2 for Peter Zijlstra
2022-02-13 18:04 ` [GIT PULL] sched/urgent for 5.17-rc4 pr-tracker-bot

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAHk-=wiHUWHHcPLCvyXQKf2wbL3L1SOQSGVuCdf-py6QZGnuqQ@mail.gmail.com' \
    --to=torvalds@linux-foundation.org \
    --cc=bp@suse.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=peterz@infradead.org \
    --cc=tadeusz.struk@linaro.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).