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[209.132.180.67]) by mx.google.com with ESMTP id k18-v6si21001020pfd.163.2018.11.12.03.42.01; Mon, 12 Nov 2018 03:42:16 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=virtuozzo.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729239AbeKLVdG (ORCPT + 99 others); Mon, 12 Nov 2018 16:33:06 -0500 Received: from relay.sw.ru ([185.231.240.75]:42294 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728302AbeKLVdG (ORCPT ); Mon, 12 Nov 2018 16:33:06 -0500 Received: from [172.16.25.12] by relay.sw.ru with esmtp (Exim 4.90_1) (envelope-from ) id 1gMAZZ-00069c-K3; Mon, 12 Nov 2018 14:40:05 +0300 Subject: Re: [PATCH] mm: cleancache: fix corruption on missed inode invalidation To: Jan Kara , Pavel Tikhomirov Cc: Andrew Morton , Vasily Averin , Konstantin Khorenko , Johannes Weiner , Mel Gorman , Matthew Wilcox , Andi Kleen , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20181112095734.17979-1-ptikhomirov@virtuozzo.com> <20181112113153.GC7175@quack2.suse.cz> From: Andrey Ryabinin Message-ID: <2abdb97e-0fed-0fb5-6941-e7afcc9e0209@virtuozzo.com> Date: Mon, 12 Nov 2018 14:40:06 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181112113153.GC7175@quack2.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/12/18 2:31 PM, Jan Kara wrote: > On Mon 12-11-18 12:57:34, Pavel Tikhomirov wrote: >> If all pages are deleted from the mapping by memory reclaim and also >> moved to the cleancache: >> >> __delete_from_page_cache >> (no shadow case) >> unaccount_page_cache_page >> cleancache_put_page >> page_cache_delete >> mapping->nrpages -= nr >> (nrpages becomes 0) >> >> We don't clean the cleancache for an inode after final file truncation >> (removal). >> >> truncate_inode_pages_final >> check (nrpages || nrexceptional) is false >> no truncate_inode_pages >> no cleancache_invalidate_inode(mapping) >> >> These way when reading the new file created with same inode we may get >> these trash leftover pages from cleancache and see wrong data instead of >> the contents of the new file. >> >> Fix it by always doing truncate_inode_pages which is already ready for >> nrpages == 0 && nrexceptional == 0 case and just invalidates inode. >> >> Fixes: commit 91b0abe36a7b ("mm + fs: store shadow entries in page cache") >> To: Andrew Morton >> Cc: Johannes Weiner >> Cc: Mel Gorman >> Cc: Jan Kara >> Cc: Matthew Wilcox >> Cc: Andi Kleen >> Cc: linux-mm@kvack.org >> Cc: linux-kernel@vger.kernel.org >> Reviewed-by: Vasily Averin >> Reviewed-by: Andrey Ryabinin >> Signed-off-by: Pavel Tikhomirov >> --- >> mm/truncate.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) > > The patch looks good but can you add a short comment before the > truncate_inode_pages() call explaining why it needs to be called always? > Something like: > > /* > * Cleancache needs notification even if there are no pages or > * shadow entries... > */ Or we can just call cleancache_invalidate_inode(mapping) on else branch, so the code would be more self-explanatory, and also avoid function call in no-cleancache setups, which should the most of setups.