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b=sYjp/pUCS09SsnpT8AOaExyGMF QCmE/suHcQz3RYLWJxkp65JDqIjmpSIl4QJx+Y5kr4hx2EqQ3E3yAPmu50OEkk5a5gQtYFbv4/Twe nXS93XBxj5ZhCtnwJF5X37TTA6soNY8nlyIg+docAg+qQBzH7pCqpHG3pM9oh5+kETJAreohIxyWM Ke2noX0qW7IjyxO4URPmFgctnH6cYRZHbzymwT1FenmnCG5p3kgcKQgwtWkCnjYNPxHiyRAgpTf5R 6ZCw7b6xNbbj3N7QlfQO3Z54K2Kwq9HqxPNphX/tagiUDaiLLHQ++slvD6+q0TyiPw+8c38eIK2kS SUL3YTrg==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1wFCFR-0000000AGpJ-1NHJ; Tue, 21 Apr 2026 14:38:45 +0000 Date: Tue, 21 Apr 2026 15:38:45 +0100 From: Matthew Wilcox To: Yibin Liu Cc: linux-mm@kvack.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, viro@zeniv.linux.org.uk, brauner@kernel.org, mjguzik@gmail.com, wujianyong@hygon.cn, huangsj@hygon.cn, zhongyuan@hygon.cn Subject: Re: [PATCH] mm: Add RWH_RMAP_EXCLUDE flag to exclude files from rmap sharing Message-ID: References: <20260421020932.3212532-1-liuyibin@hygon.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260421020932.3212532-1-liuyibin@hygon.cn> X-Rspamd-Server: rspam10 X-Stat-Signature: m87deirynst35okab8yd9jqh81np5ash X-Rspam-User: X-Rspamd-Queue-Id: A7F76C0002 X-HE-Tag: 1776782331-848529 X-HE-Meta: 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 mhy53jNm rI2AbU+cGPvIVO5NBNMoBCkzJFX/w6ZuZeisarUHGXyA1Feuz1/kRLFUueHnptMs8gSe3mdF+8dZnOeTDRmG+oO7IfmvUqt4fOtMOPJzV0Y47eQCVi7xKmXNqFlZ/5c6JaCeQKKxvdu97y2sdH0T71AYuNQvTZM5o5r89cY54fahPSqAZPuDhBEPE7zysbxutgAO2HMXGnHDXv3yTsrNsK52W0iJ9cDFpui7h4M29qW/v2N8ecdK396+gYpEVIugKU7A9hAHX860R09Ffr+cCOKIs2haG2XL7Zhe5jEvbzcdBXuYKUnO1wSo7NqmqNhN3/RNT/tqL+X4BnMU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Apr 21, 2026 at 10:09:32AM +0800, Yibin Liu wrote: > + /* Prevent truncate on files marked as RMAP_EXCLUDE (e.g., libc, ld.so) */ > + if (filp && (filp->f_mode & FMODE_RMAP_EXCLUDE)) > + return -EPERM; You can't do this. It means I can prevent anybody else from truncating a file which I can open.