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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: 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>,
	Joel Fernandes <joel@joelfernandes.org>,
	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: Fri, 10 Jul 2020 13:05:26 -0700	[thread overview]
Message-ID: <CAHk-=whPrCRZpXYKois-0t8MibxH9KVXn=+-O1YVvOA016fqhw@mail.gmail.com> (raw)
In-Reply-To: <CA+G9fYudT63yZrkWG+mfKHTcn5mP+Ay6hraEQy3G_4jufztrrA@mail.gmail.com>

On Fri, Jul 10, 2020 at 10:48 AM Naresh Kamboju
<naresh.kamboju@linaro.org> wrote:
>
> I have applied your patch and test started in a loop for a million times
> but the test ran for 35 times. Seems like the test got a timeout after 1 hour.

That just means that my test-case was wrong (in the sense that what it
was testing wasn't what was triggering things).

It might be wrong because I got the stack usage calculations wrong,
but it might be wrong simply because the bug you've triggered with LTP
needs something else to trigger.

> Re-running test with long timeouts 4 hours and will share findings.

That test was more intended to trigger the issue reliably, if it was
just a "stack is special, needs that exact 2MB aligned case to be
problematic".

So re-running my "t.c" the test for long times with that kernel patch
that removes the stack randomization isn't going to matter. Either it
triggers the case, or not.

I don't actually see any case where we play with vm_start the way we
used to (it was basically removed with commit 1be7107fbe18: "mm:
larger stack guard gap, between vmas"). So it was kind of a log shot
anyway.

              Linus

  reply	other threads:[~2020-07-10 20:05 UTC|newest]

Thread overview: 25+ 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  8:25 ` Arnd Bergmann
2020-07-10  4:17   ` Naresh Kamboju
2020-07-09 19:12 ` Linus Torvalds
2020-07-10  4:28   ` Naresh Kamboju
2020-07-10  5:22     ` Linus Torvalds
2020-07-10 17:48       ` Naresh Kamboju
2020-07-10 20:05         ` Linus Torvalds [this message]
2020-07-11 17:27           ` Naresh Kamboju
2020-07-11 18:12             ` 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 21:50       ` Joel Fernandes
2020-07-12 22:58         ` Linus Torvalds
2020-07-13  2:53           ` Joel Fernandes
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 16:08             ` Joel Fernandes
2020-07-14 16:10               ` Linus Torvalds
2020-07-14 18:12                 ` Joel Fernandes
2020-07-14 18:49                   ` Linus Torvalds

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