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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Brian Geffon <bgeffon@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	linux-api@vger.kernel.org, Andy Lutomirski <luto@amacapital.net>,
	Will Deacon <will@kernel.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Sonny Rao <sonnyrao@google.com>, Minchan Kim <minchan@kernel.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Yu Zhao <yuzhao@google.com>, Jesse Barnes <jsbarnes@google.com>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH v4] mm: Add MREMAP_DONTUNMAP to mremap().
Date: Thu, 13 Feb 2020 15:08:13 +0300	[thread overview]
Message-ID: <20200213120813.myanzyjmpyzixghf@box> (raw)
In-Reply-To: <CADyq12wcwvRLwueucHFV2ErL67etOJdFGYQdqVFM2WAeOkMGQA@mail.gmail.com>

On Mon, Feb 10, 2020 at 06:12:39AM -0800, Brian Geffon wrote:
> Hi Kirill,
> If the old_len == new_len then there is no change in the number of
> locked pages they just moved, if the new_len < old_len then the
> process of unmapping (new_len - old_len) bytes from the old mapping
> will handle the locked page accounting. So in this special case where
> we're growing the VMA, vma_to_resize() will enforce that growing the
> vma doesn't exceed RLIMIT_MEMLOCK, but vma_to_resize() doesn't handle
> incrementing mm->locked_bytes which is why we have that special case
> incrementing it here.

But if you do the operation for the VM_LOCKED vma, you'll have two locked
VMA's now, right? Where do you account the old locked vma you left behind?

-- 
 Kirill A. Shutemov

  reply	other threads:[~2020-02-13 12:07 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07 20:18 [PATCH v4] mm: Add MREMAP_DONTUNMAP to mremap() Brian Geffon
2020-02-07 20:18 ` Brian Geffon
2020-02-07 20:21 ` [PATCH] mremap.2: Add information for MREMAP_DONTUNMAP Brian Geffon
2020-02-07 20:21   ` Brian Geffon
2020-02-13 12:55   ` Christian Brauner
2020-02-10  1:21 ` [PATCH v4] mm: Add MREMAP_DONTUNMAP to mremap() Andrew Morton
2020-02-10  1:21   ` Andrew Morton
2020-02-10 18:38   ` Brian Geffon
2020-02-10 18:38     ` Brian Geffon
2020-02-10 18:38     ` Brian Geffon
2020-02-10 10:45 ` Kirill A. Shutemov
2020-02-10 14:12   ` Brian Geffon
2020-02-10 14:12     ` Brian Geffon
2020-02-13 12:08     ` Kirill A. Shutemov [this message]
2020-02-13 18:20       ` Brian Geffon
2020-02-13 18:20         ` Brian Geffon
2020-02-14  0:36         ` Kirill A. Shutemov
2020-02-11 23:13 ` Daniel Colascione
2020-02-11 23:13   ` Daniel Colascione
2020-02-11 23:32   ` Brian Geffon
2020-02-11 23:32     ` Brian Geffon
2020-02-11 23:32     ` Brian Geffon
2020-02-11 23:53     ` Daniel Colascione
2020-02-11 23:53       ` Daniel Colascione
2020-02-11 23:53       ` Daniel Colascione
2020-02-14  4:09 ` [PATCH v5 1/2] " Brian Geffon
2020-02-14  4:09   ` Brian Geffon
2020-02-14  4:09   ` [PATCH v5 2/2] selftest: Add MREMAP_DONTUNMAP selftest Brian Geffon
2020-02-14  4:09     ` Brian Geffon
2020-02-14 14:28   ` [PATCH v5 1/2] mm: Add MREMAP_DONTUNMAP to mremap() Kirill A. Shutemov
2020-02-14 18:46     ` Brian Geffon
2020-02-14 18:46       ` Brian Geffon

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