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From: Joel Fernandes <joel@joelfernandes.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	 linux-mm@kvack.org, Shuah Khan <shuah@kernel.org>,
	Vlastimil Babka <vbabka@suse.cz>,  Michal Hocko <mhocko@suse.com>,
	Lorenzo Stoakes <lstoakes@gmail.com>,
	 Kirill A Shutemov <kirill@shutemov.name>,
	"Liam R. Howlett" <liam.howlett@oracle.com>,
	 "Paul E. McKenney" <paulmck@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>
Subject: Re: [PATCH v2 1/4] mm/mremap: Optimize the start addresses in move_page_tables()
Date: Sat, 20 May 2023 00:14:23 -0400	[thread overview]
Message-ID: <CAEXW_YS-ScBYeTtj7PTZSSYXeApsZ1vhTpBFtq5jNA_R9055=Q@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wh3tjw+MNxe6zuixtD=D8bXYHWs9h3Y++r5ObTcSvz6+A@mail.gmail.com>

On Sat, May 20, 2023 at 12:01 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Fri, May 19, 2023 at 8:57 PM Joel Fernandes <joel@joelfernandes.org> wrote:
> >
> > I also realize that I don't really need to check whether the masked
> > source address falls under a VMA neighboring to that of the source's.
>
> I don't think that's true.
>
> You can't start randomly moving other source vma's that may have other contents.

If the beginning part of the PMD is not mapped at the destination, I
thought maybe a whole PMD could be moved to it. But I guess not
because we don't want those contents to be accessible. So then in that
case we have to forbid the optimization for all intra-VMA moves except
those involving the stack. I will think more about it.

Thanks,

 - Joel


  reply	other threads:[~2023-05-20  4:14 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-19 19:09 [PATCH v2 0/4] Optimize mremap during mutual alignment within PMD Joel Fernandes (Google)
2023-05-19 19:09 ` [PATCH v2 1/4] mm/mremap: Optimize the start addresses in move_page_tables() Joel Fernandes (Google)
2023-05-19 19:21   ` Linus Torvalds
2023-05-19 22:52     ` Joel Fernandes
2023-05-20  2:34       ` Linus Torvalds
2023-05-20  3:17         ` Joel Fernandes
2023-05-20  3:56           ` Joel Fernandes
2023-05-20  4:01             ` Linus Torvalds
2023-05-20  4:14               ` Joel Fernandes [this message]
2023-05-20  4:22                 ` Joel Fernandes
2023-05-20  5:04               ` Joel Fernandes
2023-05-19 19:09 ` [PATCH v2 2/4] selftests: mm: Fix failure case when new remap region was not found Joel Fernandes (Google)
2023-05-19 19:09 ` [PATCH v2 3/4] selftests: mm: Add a test for mutually aligned moves > PMD size Joel Fernandes (Google)
2023-05-19 19:09 ` [PATCH v2 4/4] selftests: mm: Add a test for remapping to area immediately after existing mapping Joel Fernandes (Google)

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