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Thu, 01 Feb 2024 23:48:42 -0500 X-MC-Unique: Ua2OcVI-PcSJtTR88LE0oA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0EB0B38117FB; Fri, 2 Feb 2024 04:48:42 +0000 (UTC) Received: from fedora (unknown [10.72.116.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 41BD21121306; Fri, 2 Feb 2024 04:48:35 +0000 (UTC) Date: Fri, 2 Feb 2024 12:48:28 +0800 From: Ming Lei To: Matthew Wilcox Cc: Andrew Morton , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, David Hildenbrand , Alexander Viro , Christian Brauner , Don Dutile , Rafael Aquini , Dave Chinner , Mike Snitzer , ming.lei@redhat.com Subject: Re: [PATCH] mm/madvise: set ra_pages as device max request size during ADV_POPULATE_READ Message-ID: References: <20240202022029.1903629-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: D4A57C0019 X-Stat-Signature: 1zotskipb91na5pmfji8og5wbjnbae5q X-Rspam-User: X-HE-Tag: 1706849324-711544 X-HE-Meta: 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 8X75MXrQ ds8ioV3YC6Jbx59djZ+N6wZeSktUYxyfdudv4pCcPMOQQfAR/2rnVQUHoeq0p3JpBKfT/whEqBBhqomof2wwixnALRoao4fuIEG1TymWcxAmSqip5ELQiZUPQMG7wka674bAiCQxgj5sD4BteXW8ojX/iOhlj/uVqCJinDT2tKWkwXDwtRn0KzZU8q5iMI9k4KCOCM+I9s+9hBqY= 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, Feb 02, 2024 at 04:15:39AM +0000, Matthew Wilcox wrote: > On Fri, Feb 02, 2024 at 10:20:29AM +0800, Ming Lei wrote: > > +static struct file *madvise_override_ra_win(struct file *f, > > + unsigned long start, unsigned long end, > > + unsigned int *old_ra_pages) > > +{ > > + unsigned int io_pages; > > + > > + if (!f || !f->f_mapping || !f->f_mapping->host) > > + return NULL; > > How can ->f_mapping be NULL? How can f_mapping->host be NULL? You are right, the two checks can be removed because both two won't be NULL for opened file, and .f_ra is initialized with f->f_mapping->host->i_mapping directly too. I will drop the checks in next version. BTW, looks the same check in madvise_remove() can removed too. Thanks, Ming