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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <1668172.1709764777@warthog.procyon.org.uk> To: Matthew Wilcox , Trond Myklebust Cc: dhowells@redhat.com, Christoph Hellwig , Andrew Morton , Alexander Viro , Christian Brauner , Jeff Layton , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, netfs@lists.linux.dev, v9fs@lists.linux.dev, linux-afs@lists.infradead.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, devel@lists.orangefs.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] mm: Replace ->launder_folio() with flush and wait MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1821329.1709800001.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 07 Mar 2024 08:26:41 +0000 Message-ID: <1821330.1709800001@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 5FAA540006 X-Stat-Signature: tjhsonm6c8mnei9qsh1ckm99a9rya8yu X-Rspam-User: X-HE-Tag: 1709800009-223448 X-HE-Meta: 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 Raw3HPI2 5tUoeDcZx6XJPLw0HfnDzklaQHZV1Sictl2s4tuvlOMWJ8JlQCPYzlVc8hemEm4cfshcB4pLZ3mQujkb9kyiyylk0k1FYJhX6sC2j34lskeG3wpgMnTCZK3q7nWF0XZalYElzZQEZImYVUsXxm0q4gt9NyQD2oLR7OS9tGnNQbduAD4OgAk6Rn4JrEwjAKMKYBYxRTfzKR7fKtB9k00W3nn6cVJHHUaz2qyaxZo6hRiTJkXhBEqxCikbxH2mPua6U6WElr38fCqt3KnxKUFFrYQG5P5omQNNp1mISUydVJJMQRCMfaZqxMFQx8atrdNi5JgZE 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: Matthew Wilcox wrote: > commit e3db7691e9f3dff3289f64e3d98583e28afe03db > Author: Trond Myklebust > Date: Wed Jan 10 23:15:39 2007 -0800 > = > [PATCH] NFS: Fix race in nfs_release_page() >... = > invalidate_inode_pages2() may find the dirty bit has been set on a= page > owing to the fact that the page may still be mapped after it was l= ocked. > Only after the call to unmap_mapping_range() are we sure that the = page > can no longer be dirtied. Is that last sentence even true? It evicts folios from the TLB and/or pagetables, but it doesn't actually trim any mmap made - in which case, userspace is perfectly at liberty to regenerate and dirty the folio the mo= ment the folio is removed from the page tables. Otherwise DIO-to/from-mmap wil= l deadlock. > but my belief is that we should be able to get rid of it. I think you're probably correct. The best we can do, I think, is to prefa= ce any call to invalidate_inode_pages2() with a flush-and-wait over the same range. David