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Tue, 03 Jan 2023 12:27:45 -0800 (PST) MIME-Version: 1.0 References: <20230101230042.244286-1-jthoughton@google.com> In-Reply-To: From: James Houghton Date: Tue, 3 Jan 2023 20:27:34 +0000 Message-ID: Subject: Re: [PATCH] hugetlb: unshare some PMDs when splitting VMAs To: Mike Kravetz Cc: Muchun Song , Peter Xu , Axel Rasmussen , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: B025BC000E X-Stat-Signature: wgazod7ffajcwq8kkn534bx7qqqwaoob X-HE-Tag: 1672778164-273636 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000031, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > I think I've come up with one... :) It only took many many hours of > staring at code to come up with: > > 1. Fault in PUD_SIZE-aligned hugetlb mapping > 2. fork() (to actually share the PMDs) Erm, I mean: mmap(), then fork(), then fault in both processes.