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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
	Naresh Kamboju <naresh.kamboju@linaro.org>,
	linux- stable <stable@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>, Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>, Michal Hocko <mhocko@kernel.org>,
	lkft-triage@lists.linaro.org, Chris Down <chris@chrisdown.name>,
	Michel Lespinasse <walken@google.com>,
	Fan Yang <Fan_Yang@sjtu.edu.cn>,
	Brian Geffon <bgeffon@google.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	pugaowei@gmail.com, Jerome Glisse <jglisse@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	Hugh Dickins <hughd@google.com>,
	Al Viro <viro@zeniv.linux.org.uk>, Tejun Heo <tj@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: Re: WARNING: at mm/mremap.c:211 move_page_tables in i386
Date: Tue, 14 Jul 2020 11:49:20 -0700	[thread overview]
Message-ID: <CAHk-=wgRS_WpRdC9nyXzVZ7aWNQt0HKMbyFjhrgrNo49AFNWzg@mail.gmail.com> (raw)
In-Reply-To: <CAEXW_YRTnCb-z6TeboA3OCYv8eoX8UiCNn7K1hGMX+41Zdz8Og@mail.gmail.com>

On Tue, Jul 14, 2020 at 11:12 AM Joel Fernandes <joel@joelfernandes.org> wrote:
>
> I think you misunderstood me. I was not advocating breaking the stack
> movement code or breaking stack randomization, I was going to try to
> see if I could keep that working while not having to do an overlapping
> move.

I'm not really seeing how you'd do that with a big stack that gets
close to the stack ulimit.

Except by avoiding randomization.

But the existing randomization may be so bad that it doesn't much
matter. And I do think we limit the execve stack to a reasonably small
fraction of the whole ulimit. So worth exploring, I guess.

The current code with "align_stack" doing randomization could also do
with a lot of clarifications. The code is odd.

            Linus

  reply	other threads:[~2020-07-14 18:49 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-09  5:28 WARNING: at mm/mremap.c:211 move_page_tables in i386 Naresh Kamboju
2020-07-09  5:28 ` Naresh Kamboju
2020-07-09  8:25 ` Arnd Bergmann
2020-07-10  4:17   ` Naresh Kamboju
2020-07-09 19:12 ` Linus Torvalds
2020-07-09 19:12   ` Linus Torvalds
2020-07-10  4:28   ` Naresh Kamboju
2020-07-10  4:28     ` Naresh Kamboju
2020-07-10  5:22     ` Linus Torvalds
2020-07-10  5:22       ` Linus Torvalds
2020-07-10 17:48       ` Naresh Kamboju
2020-07-10 17:48         ` Naresh Kamboju
2020-07-10 20:05         ` Linus Torvalds
2020-07-10 20:05           ` Linus Torvalds
2020-07-11 17:27           ` Naresh Kamboju
2020-07-11 17:27             ` Naresh Kamboju
2020-07-11 18:12             ` Linus Torvalds
2020-07-11 18:12               ` Linus Torvalds
2020-07-11 18:21               ` Linus Torvalds
2020-07-11 18:21                 ` Linus Torvalds
2020-07-11 23:33               ` Joel Fernandes
2020-07-12 17:30               ` Matthew Wilcox
2020-07-12 20:38                 ` Linus Torvalds
2020-07-12 20:38                   ` Linus Torvalds
2020-07-12 21:50       ` Joel Fernandes
2020-07-12 22:58         ` Linus Torvalds
2020-07-12 22:58           ` Linus Torvalds
2020-07-13  2:53           ` Joel Fernandes
2020-07-13  3:51             ` Linus Torvalds
2020-07-13  3:51               ` Linus Torvalds
2020-07-13 12:12               ` Joel Fernandes
2020-07-14  7:33           ` Kirill A. Shutemov
2020-07-14 11:27             ` Naresh Kamboju
2020-07-14 11:27               ` Naresh Kamboju
2020-07-14 16:08             ` Joel Fernandes
2020-07-14 16:10               ` Linus Torvalds
2020-07-14 16:10                 ` Linus Torvalds
2020-07-14 18:12                 ` Joel Fernandes
2020-07-14 18:12                   ` Joel Fernandes
2020-07-14 18:49                   ` Linus Torvalds [this message]
2020-07-14 18:49                     ` Linus Torvalds

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