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[24.6.216.183]) by smtp.gmail.com with ESMTPSA id g8sm16583032pfv.51.2021.09.27.05.59.51 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Sep 2021 05:59:52 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Subject: Re: [RFC PATCH 1/8] mm/madvise: propagate vma->vm_end changes From: Nadav Amit In-Reply-To: <20210927124518.gjas4itro5c3park@box.shutemov.name> Date: Mon, 27 Sep 2021 05:59:50 -0700 Cc: Andrew Morton , Linux-MM , Linux Kernel Mailing List , Peter Xu , Andrea Arcangeli , Minchan Kim , Colin Cross , Suren Baghdasarya , Mike Rapoport Content-Transfer-Encoding: quoted-printable Message-Id: <6496185C-6792-4D67-AF5D-E049A8DC65B8@gmail.com> References: <20210926161259.238054-1-namit@vmware.com> <20210926161259.238054-2-namit@vmware.com> <20210927090852.sc5u65ufwvfx57rl@box.shutemov.name> <20210927115507.6xfpugeg3swookbh@box> <4211F6D4-A282-4AB4-8D96-E273C5ABE0DF@gmail.com> <20210927124518.gjas4itro5c3park@box.shutemov.name> To: "Kirill A. Shutemov" X-Mailer: Apple Mail (2.3654.120.0.1.13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Sep 27, 2021, at 5:45 AM, Kirill A. Shutemov = wrote: >=20 > On Mon, Sep 27, 2021 at 05:33:39AM -0700, Nadav Amit wrote: >>=20 >>=20 >>> On Sep 27, 2021, at 4:55 AM, Kirill A. Shutemov = wrote: >>>=20 >>> On Mon, Sep 27, 2021 at 03:11:20AM -0700, Nadav Amit wrote: >>>>=20 >>>>> On Sep 27, 2021, at 2:08 AM, Kirill A. Shutemov = wrote: >>>>>=20 >>>>> On Sun, Sep 26, 2021 at 09:12:52AM -0700, Nadav Amit wrote: >>>>>> From: Nadav Amit >>>>>>=20 >>>>>> The comment in madvise_dontneed_free() says that vma splits that = occur >>>>>> while the mmap-lock is dropped, during userfaultfd_remove(), = should be >>>>>> handled correctly, but nothing in the code indicates that it is = so: prev >>>>>> is invalidated, and do_madvise() will therefore continue to = update VMAs >>>>>> from the "obsolete" end (i.e., the one before the split). >>>>>>=20 >>=20 [snip] >> Perhaps adding this one on top of yours? I can test it when I wake = up. >> It is cleaner, but I am not sure if I am missing something. >=20 > It should work. >=20 > BTW, shouldn't we bring madvise_willneed() and madvise_remove() to the > same scheme? Even for consistency you are right. My only problem is that I am afraid to backport such a change. For MADV_DONTNEED, I saw an explicit = assumption. I can do it all in one patch if we agree that none of it goes into = stable (which I clumsily forgot to cc, but might find the patch and backport = it).=