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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 called
from the vm_operations_struct::fault() context during the page fault.
This context doesn't need the reclaim protection normally.

ceph and ocfs2 which call filemap_fault from their fault handlers seem
to be OK because they are not taking any fs lock before invoking generic
implementation.  xfs which takes XFS_MMAPLOCK_SHARED is safe from the
reclaim recursion POV because this lock serializes truncate and punch
hole with the page faults and it doesn't get involved in the reclaim.

There is simply no reason to deliberately use a weaker allocation
context when a __GFP_FS | __GFP_IO can be used.  The GFP_NOFS protection
might be even harmful.  There is a push to fail GFP_NO...