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Tue, 08 Nov 2022 13:05:41 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Re: [PATCH 4/4] mm: delay page_remove_rmap() until after the TLB has been flushed From: Nadav Amit In-Reply-To: <20221108194139.57604-4-torvalds@linux-foundation.org> Date: Tue, 8 Nov 2022 13:05:39 -0800 Cc: Hugh Dickins , Johannes Weiner , Andrew Morton , kernel list , Linux-MM , Will Deacon , Aneesh Kumar , Nick Piggin , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Peter Zijlstra , Gerald Schaefer , David Hildenbrand Content-Transfer-Encoding: quoted-printable Message-Id: <519E803D-4D58-4252-B596-A40D7C156BC1@gmail.com> References: <20221108194139.57604-4-torvalds@linux-foundation.org> To: Linus Torvalds X-Mailer: Apple Mail (2.3696.120.41.1.1) ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=mcJaYuu2; spf=pass (imf14.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.214.174 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com; 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dkim=pass header.d=gmail.com header.s=20210112 header.b=mcJaYuu2; spf=pass (imf14.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.214.174 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Stat-Signature: nik9inicnr44us6994tu8fyj5w7pfck4 X-HE-Tag: 1667941555-888797 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Nov 8, 2022, at 11:41 AM, Linus Torvalds = wrote: > When we remove a page table entry, we are very careful to only free = the > page after we have flushed the TLB, because other CPUs could still be > using the page through stale TLB entries until after the flush. The patches (all 4) look fine to me. I mean there are minor issues here and there, like s390=E2=80=99s = tlb_flush_rmaps() that can have VM_WARN_ON(1);the generic tlb_flush_rmaps() that is = missing an empty line after the =E2=80=98page' variable definition; or perhaps = using __bitwise for sparse (as David pointed) =E2=80=94 but it can all be addressed = later.