From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by kanga.kvack.org (Postfix) with ESMTP id 4BA4F6B0038 for ; Thu, 19 Mar 2015 03:15:13 -0400 (EDT) Received: by pabxg6 with SMTP id xg6so54400052pab.0 for ; Thu, 19 Mar 2015 00:15:13 -0700 (PDT) Received: from ipmail07.adl2.internode.on.net (ipmail07.adl2.internode.on.net. [150.101.137.131]) by mx.google.com with ESMTP id b1si831715pat.205.2015.03.19.00.15.11 for ; Thu, 19 Mar 2015 00:15:12 -0700 (PDT) Date: Thu, 19 Mar 2015 18:14:39 +1100 From: Dave Chinner Subject: Re: [PATCH] mm: Use GFP_KERNEL allocation for the page cache in page_cache_read Message-ID: <20150319071439.GE28621@dastard> References: <1426687766-518-1-git-send-email-mhocko@suse.cz> <55098F3B.7070000@redhat.com> <20150318145528.GK17241@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150318145528.GK17241@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Rik van Riel , Andrew Morton , Al Viro , Johannes Weiner , Mel Gorman , Neil Brown , Tetsuo Handa , Sage Weil , Mark Fasheh , linux-mm@kvack.org, LKML On Wed, Mar 18, 2015 at 03:55:28PM +0100, Michal Hocko wrote: > On Wed 18-03-15 10:44:11, Rik van Riel wrote: > > On 03/18/2015 10:09 AM, Michal Hocko wrote: > > > page_cache_read has been historically using page_cache_alloc_cold to > > > allocate a new page. This means that mapping_gfp_mask is used as the > > > base for the gfp_mask. Many filesystems are setting this mask to > > > GFP_NOFS to prevent from fs recursion issues. page_cache_read is, > > > however, not called from the fs layer > > > > Is that true for filesystems that have directories in > > the page cache? > > I haven't found any explicit callers of filemap_fault except for ocfs2 > and ceph and those seem OK to me. Which filesystems you have in mind? Just about every major filesystem calls filemap_fault through the .fault callout. C symbol: filemap_fault File Function Line 0 9p/vfs_file.c 831 .fault = filemap_fault, 1 9p/vfs_file.c 838 .fault = filemap_fault, 2 btrfs/file.c 2081 .fault = filemap_fault, 3 cifs/file.c 3242 .fault = filemap_fault, 4 ext4/file.c 215 .fault = filemap_fault, 5 f2fs/file.c 93 .fault = filemap_fault, 6 fuse/file.c 2062 .fault = filemap_fault, 7 gfs2/file.c 498 .fault = filemap_fault, 8 nfs/file.c 653 .fault = filemap_fault, 9 nilfs2/file.c 128 .fault = filemap_fault, a ubifs/file.c 1536 .fault = filemap_fault, b xfs/xfs_file.c 1420 .fault = filemap_fault, > Btw. how would that work as we already have GFP_KERNEL allocation few > lines below? GFP_KERNEL allocation for mappings is simply wrong. All mapping allocations where the caller cannot pass a gfp_mask need to obey the mapping_gfp_mask that is set by the mapping owner.... Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org