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 <global> 831 .fault = filemap_fault, 1 9p/vfs_file.c <global> 838 .fault = filemap_fault, 2 btrfs/file.c <global> 2081 .fault = filemap_fault, 3 cifs/file.c <global> 3242 .fault = filemap_fault, 4 ext4/file.c <global> 215 .fault = filemap_fault, 5 f2fs/file.c <global> 93 .fault = filemap_fault, 6 fuse/file.c <global> 2062 .fault = filemap_fault, 7 gfs2/file.c <global> 498 .fault = filemap_fault, 8 nfs/file.c <global> 653 .fault = filemap_fault, 9 nilfs2/file.c <global> 128 .fault = filemap_fault, a ubifs/file.c <global> 1536 .fault = filemap_fault, b xfs/xfs_file.c <global> 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@xxxxxxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>