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[18.9.28.11]) by mx.google.com with ESMTPS id t8si2467655wrv.130.2019.05.24.09.52.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 May 2019 09:52:28 -0700 (PDT) Received-SPF: pass (google.com: domain of tytso@mit.edu designates 18.9.28.11 as permitted sender) client-ip=18.9.28.11; Authentication-Results: mx.google.com; spf=pass (google.com: domain of tytso@mit.edu designates 18.9.28.11 as permitted sender) smtp.mailfrom=tytso@mit.edu Received: from callcc.thunk.org (guestnat-104-133-0-109.corp.google.com [104.133.0.109] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x4OGqDtZ028397 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 24 May 2019 12:52:16 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 421D9420481; Fri, 24 May 2019 12:52:13 -0400 (EDT) Date: Fri, 24 May 2019 12:52:13 -0400 From: "Theodore Ts'o" To: Sahitya Tummala Cc: Andrew Morton , Kirill Tkhai , Michal Hocko , Johannes Weiner , Vladimir Davydov , Yafang Shao , Roman Gushchin , Mel Gorman , linux-mm@kvack.org, Jaegeuk Kim , Eric Biggers , linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/vmscan.c: drop all inode/dentry cache from LRU Message-ID: <20190524165213.GB2765@mit.edu> Mail-Followup-To: Theodore Ts'o , Sahitya Tummala , Andrew Morton , Kirill Tkhai , Michal Hocko , Johannes Weiner , Vladimir Davydov , Yafang Shao , Roman Gushchin , Mel Gorman , linux-mm@kvack.org, Jaegeuk Kim , Eric Biggers , linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org References: <1558685161-860-1-git-send-email-stummala@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1558685161-860-1-git-send-email-stummala@codeaurora.org> User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Fri, May 24, 2019 at 01:36:01PM +0530, Sahitya Tummala wrote: > This is important for the scenario where FBE (file based encryption) > is enabled. With FBE, the encryption context needed to en/decrypt a file > will be stored in inode and any inode that is left in the cache after > drop_caches is done will be a problem. For ex, in Android, drop_caches > will be used when switching work profiles. > > Signed-off-by: Sahitya Tummala Instead of making a change to vmscan.c, it's probably better to migrate to the new fscrypt key-management framework, which solves this problem with an explicit FS_IOC_REMOVE_ENCRYPTION_KEY ioctl. This allows the system to remove all inodes that were made available via a single key without having nuking all other inodes --- this would make it much faster after a user logs out of ChromeOS, for example: See: https://patchwork.kernel.org/patch/10952019/ - Ted