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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1r1VyO-00EqYU-IO; Fri, 10 Nov 2023 18:11:16 +0000 Date: Fri, 10 Nov 2023 18:11:16 +0000 From: Matthew Wilcox To: Kefeng Wang Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Gregory Price Subject: Re: [PATCH v2 1/7] fs/proc/page: remove unneeded PageTail && PageSlab check Message-ID: References: <20231110033324.2455523-1-wangkefeng.wang@huawei.com> <20231110033324.2455523-2-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231110033324.2455523-2-wangkefeng.wang@huawei.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B53F3C000E X-Stat-Signature: 9uk5dhsuarbrxud16qt8gk7ih891yd5q X-Rspam-User: X-HE-Tag: 1699639896-593683 X-HE-Meta: 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 kum72aq4 HSJG/3WgxiuHK3V4Bz+67/b5pZJ27fsD/p0paAZA8MpsE6NLq0GQ+IQHv209Nm216NmG//CkXOqYJm+rlyRQ/LI5ILarCa2kNT7WHkc9VP9iZ/1Q8BCRaVMBtowbSGlIrONezHJ2az2fz7wn63bvdJgMltdykIRXq4cDr 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: List-Subscribe: List-Unsubscribe: On Fri, Nov 10, 2023 at 11:33:18AM +0800, Kefeng Wang wrote: > After commit dcb351cd095a ("page-flags: define behavior SL*B-related > flags on compound pages"), the slab could not be a tail, remove unneeded > PageTail && PageSlab check. No, that's completely wrong. * PF_NO_TAIL: * modifications of the page flag must be done on small or head pages, * checks can be done on tail pages too. That's backed up by the code: #define PF_NO_TAIL(page, enforce) ({ \ VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \ PF_POISONED_CHECK(compound_head(page)); }) (enforce is set to 0 for the 'test') > Signed-off-by: Kefeng Wang NAK