LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
To: Ferry Toth <ftoth@telfort.nl>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
	Mike Galbraith <efault@gmx.de>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: DOS by unprivileged user
Date: Mon, 30 Apr 2018 12:35:25 +0200	[thread overview]
Message-ID: <CANiq72kkGrn0fGVMB=ht48_wM4Fy=KotiHed+efB2Gf9heeM6Q@mail.gmail.com> (raw)
In-Reply-To: <12218300.6oQjICIiUq@ferry-quad>

On Mon, Apr 30, 2018 at 12:00 PM, Ferry Toth <ftoth@telfort.nl> wrote:
> Op woensdag 25 april 2018 16:54:59 CEST schreef Alan Cox:
>> > > I think memory allocation and io waits can't be decoupled from
>> > > scheduling as they are now.
>> >
>> > The scheduler is not decoupled from either, it is intimately involved
>> > in both.  However, none of the decision making smarts for either reside
>> > in the scheduler, nor should they.
>>
>> It belongs in both.
>>
>> Classical Unix systems never had this problem because they respond to
>> thrashing by ensuring that all processes consumed CPU and made some
>> progress. Linux handles it by thrashing itself to dealth while BSD always
>> handled it by moving from paging more towards swapping and behaving like
>> a swap bound batch machine.
>>
>> Linux thrashes itself to death, the classic BSD algorithn instead throws
>> fairness out of the window under extreme load to prevent it. It might take
>> a few seconds but at least you will get your prompt back.
>>
>> Alan
>>
> I haven t tried BSD.
>
> But when I was young I allocated 10MB on a HP9000 (UX) with 1MB of RAM. People wanted to launch me out of the window (18th floor).
>
> I did not want to say Unix was better, only with so much emphasis on security I' m surprised how easy it is for a regular user to bring linux to on it s knees.

While it is true that things can be improved/tweaked for typical
desktop/single user usage; this isn't really a security issue. For
shared systems, there are a few ways to soft/hard limit resources:
nice, *limit, cgroups, systemd limits, containers/VMs...

Cheers,
Miguel

      reply	other threads:[~2018-04-30 10:35 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 19:13 Ferry Toth
2018-04-20  4:46 ` Mike Galbraith
2018-04-20  8:39   ` Ferry Toth
2018-04-20 12:37     ` Mike Galbraith
2018-04-22 10:16 ` Pavel Machek
2018-04-22 17:43   ` vcaputo
2018-04-23  0:27     ` Michal Hocko
2018-04-23  7:13       ` Pavel Machek
     [not found] ` <4285098.DEWjdbWF2X@delfion>
     [not found]   ` <1524325275.8078.2.camel@gmx.de>
     [not found]     ` <6057755.ozdVOybsI6@delfion>
2018-04-23  8:04       ` Mike Galbraith
2018-04-25 14:54         ` Alan Cox
2018-04-25 16:21           ` Mike Galbraith
2018-04-25 16:50           ` Mike Galbraith
2018-04-30 10:00           ` Ferry Toth
2018-04-30 10:35             ` Miguel Ojeda [this message]

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='CANiq72kkGrn0fGVMB=ht48_wM4Fy=KotiHed+efB2Gf9heeM6Q@mail.gmail.com' \
    --to=miguel.ojeda.sandonis@gmail.com \
    --cc=efault@gmx.de \
    --cc=ftoth@telfort.nl \
    --cc=gnomes@lxorguk.ukuu.org.uk \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: DOS by unprivileged user' \
    /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

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).