From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2753128-1517969794-2-6896181094347454147 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='edu', MailFrom='org' X-Spam-charsets: plain='us-ascii' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1517969793; b=sjZhT613FKsd+YOTpPOlISJmeIH0TgUUqrCdKFR2/eyie9x 1GnUOCgxsWHBAxFv0UN2ojKqLlFGKEORa+akvucGKvJ0FQO8/vFmBYQUusIxUubV XLiYK/WA73v0mivt56p/QW4K1p+QpCjzwJ2623U2WRCGrNwpixRyhGaMs9QOb0AO qR4TPqIWfdv+wKd4WEVcv456umd6RzrV1sCClkBZjGCh3isRe0pjedTsEipR6GOT IaPQ9M4OXaFc4pyBDN/hAPLCz2s1g0DX3hlixonnIl7x+Fu4kq6mnpF3Fr8eRJbM q8aRHqulKqcWsYRJHScUqU5CuIqmbIRICXnKARw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to:sender :list-id; s=arctest; t=1517969793; bh=9IeOISo4AY+eTLTP8C07r0TokL dTx6TJoV/uHxhlREY=; b=foayYQlzynCefZu+P9p5ciVjWGTbevB0Ub0sMNO2gp ACnRqs1hBH7s/8c0IgvqppJ6ymYbHF2sexT9ALHv1IXWIivYJOhAQF1myK33F/C/ k0zqaUcB62jO4owLtfL2W1plMPY8lMhVOPl45cZQRZ+oPufumRivShSoAilkJHg/ ObMKnKSxgxf9Q/xBQ4N5GmpSe4gz0FT+D1rlWgwk2S8yPieqGEMAQNisfvGzFUg2 naJZ4NsoxEQt48bMy4QTxSZ06ObKZ/EuqV/Aati4RXA18s/0UXzfY7dYdy5Y95Ft rBCzikCBF0vaUhXQKoNNQPttu+du8HtpGUcH+8ShH/Gw== ARC-Authentication-Results: i=1; mx6.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 1024-bit rsa key sha256) header.d=thunk.org header.i=@thunk.org header.b=CvkzW0UT x-bits=1024 x-keytype=rsa x-algorithm=sha256 x-selector=ef5046eb; dmarc=none (p=none,has-list-id=yes,d=none) header.from=mit.edu; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=mit.edu header.result=pass header_is_org_domain=yes Authentication-Results: mx6.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 1024-bit rsa key sha256) header.d=thunk.org header.i=@thunk.org header.b=CvkzW0UT x-bits=1024 x-keytype=rsa x-algorithm=sha256 x-selector=ef5046eb; dmarc=none (p=none,has-list-id=yes,d=none) header.from=mit.edu; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=mit.edu header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752952AbeBGCQb (ORCPT ); Tue, 6 Feb 2018 21:16:31 -0500 Received: from imap.thunk.org ([74.207.234.97]:44660 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752786AbeBGCQ3 (ORCPT ); Tue, 6 Feb 2018 21:16:29 -0500 Date: Tue, 6 Feb 2018 21:16:17 -0500 From: Theodore Ts'o To: Eric Biggers Cc: Greg KH , Jin Qian , Andreas Dilger , Alexander Viro , Jeff Layton , "J. Bruce Fields" , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jin Qian , stable@vger.kernel.org Subject: Re: [PATCHv2 1/1] ext4: don't put symlink in pagecache into highmem Message-ID: <20180207021617.GD1977@thunk.org> Mail-Followup-To: Theodore Ts'o , Eric Biggers , Greg KH , Jin Qian , Andreas Dilger , Alexander Viro , Jeff Layton , "J. Bruce Fields" , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jin Qian , stable@vger.kernel.org References: <20180206190938.172792-1-jinqian@android.com> <20180206203953.GC18045@kroah.com> <20180206231149.GC1977@thunk.org> <20180206233809.GA159960@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180206233809.GA159960@gmail.com> User-Agent: Mutt/1.9.3 (2018-01-21) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, Feb 06, 2018 at 03:38:09PM -0800, Eric Biggers wrote: > I don't think backporting this change for other filesystems is particularly > important, since if I understand correctly, the reasons that Al made the change > originally were: > > - to allow following symlinks in RCU mode, but that's not implemented in old > kernels Yup. > - to prevent a process from using up all kmaps and deadlocking the system, which > I'm not sure is a real problem (someone would need to try to put together a > reproducer), but if so it would probably just be a local device of service. .. and *that's* only a problem on 32-bit systems. And aside from Android, it's unclear to me how much we need to support 32-bit systems on upstream LTS kernels. I suppose there might be Rasperry PI's which are 32-bits and which might want to use btrfs. Personally I'm not sure we should care all that much, but others who care more about LTS kernels and 32-bit systems might have a different opinion. > Also if we actually backported the full commit there are follow-on fixes such as > e8ecde25f5e that would be needed as well but might be missed. Good point. - Ted