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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sHlsF-0000000FsPE-0xXi; Thu, 13 Jun 2024 14:56:23 +0000 Date: Thu, 13 Jun 2024 15:56:23 +0100 From: Matthew Wilcox To: Dan Carpenter Cc: David Howells , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [bug report] mm: Provide a means of invalidation without using launder_folio Message-ID: References: <8b6bd8e0-04a2-4b51-9b29-74804ba11564@moroto.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8b6bd8e0-04a2-4b51-9b29-74804ba11564@moroto.mountain> X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 8C11C40011 X-Stat-Signature: jgeuq7ptb9wqeuxcpseiocbxrioiaoy1 X-HE-Tag: 1718290585-914006 X-HE-Meta: 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 Pd//CzUl H1B4LKurkv/OwQvvat57Kag8qPcxiNxa8MuEFFXNm3zgtyza6wFJXNJrui1yQ711O+vvqqsF99IQdLgiF/WjYbWMnBb26tfv61F6MPf0NSz7Yu2DfvHI5jAhNfrNbRXs+Yz1CV5Jw28+doRU8zangwDc+iKVxD57ahtFlJ3pfKC3JETDhqLw5Z7bVAKPzOFLRuz6P0Wr8yoLR4/S9r/VAuWI/4FPJdCkiYhI2CXcKps3KWG5zagZS+vo3M2kVm6KFZmSyDcPXQinFt7aZ049dmW8mpQ== 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, Jun 13, 2024 at 04:55:30PM +0300, Dan Carpenter wrote: > Hello David Howells, > > Commit 74e797d79cf1 ("mm: Provide a means of invalidation without > using launder_folio") from Mar 27, 2024 (linux-next), leads to the > following Smatch static checker warning: > > mm/filemap.c:4229 filemap_invalidate_inode() > error: we previously assumed 'mapping' could be null (see line 4200) I think David has been overly cautious here. I don't think i_mapping can ever be NULL. inode_init_always() sets i_mapping to be &inode->i_data and I don't see anywhere that changes i_mapping to be NULL. > mm/filemap.c > 4192 int filemap_invalidate_inode(struct inode *inode, bool flush, > 4193 loff_t start, loff_t end) > 4194 { > 4195 struct address_space *mapping = inode->i_mapping; > 4196 pgoff_t first = start >> PAGE_SHIFT; > 4197 pgoff_t last = end >> PAGE_SHIFT; > 4198 pgoff_t nr = end == LLONG_MAX ? ULONG_MAX : last - first + 1; > 4199 > 4200 if (!mapping || !mapping->nrpages || end < start) > ^^^^^^^^ > If mapping is NULL