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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rWha5-00000007KJG-2Fgk; Sun, 04 Feb 2024 18:51:05 +0000 Date: Sun, 4 Feb 2024 18:51:05 +0000 From: Matthew Wilcox To: Qi Zheng Cc: akpm@linux-foundation.org, arnd@arndb.de, muchun.song@linux.dev, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH 1/2] mm: pgtable: add missing flag and statistics for kernel PTE page Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 985A78000F X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: g6kacec3753tkuz8ec99tcxkz6aadnxt X-HE-Tag: 1707072671-128849 X-HE-Meta: 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 zY4q0cob mNBGBZzUC4IS2CDRwY99DHifwuyDpAPk7DA81SrwKS15ZXGd77uuqALyj0asE+5kQ8gIOQADPaSDc6+FB6gn5fHpKhMfcTl/ST8Qtb3wkUJFGVoZU0Jle1A9mOma/wrrQQ2tZjL+u17i4LLweRIpOdPPd3MP9J2Syh3PF 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 Thu, Feb 01, 2024 at 04:05:40PM +0800, Qi Zheng wrote: > For kernel PTE page, we do not need to allocate and initialize its split > ptlock, but as a page table page, it's still necessary to add PG_table > flag and NR_PAGETABLE statistics for it. No, this is wrong. We do not account _kernel_ page tables to the _user_. Just because the kernel, say, called vmalloc() doesn't mean we should charge the task for it. Moreover, one task may call vmalloc() and a different task would then call vfree(). This is a can of worms you don't want to open. Why did you want to do this?