Messages in this thread | | | 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 |
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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@fromorbit.com
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