mm: allow THP orders for PFNMAPs

This enables PFNMAPs to be mapped at either pmd/pud layers.  Generalize the
dax case into vma_is_special_huge() so as to cover both.  Meanwhile, rename
the macro to THP_ORDERS_ALL_SPECIAL.

Link: https://lkml.kernel.org/r/20240826204353.2228736-5-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Gavin Shan <gshan@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/huge_mm.h

@@ -76,9 +76,9 @@ extern struct kobj_attribute thpsize_shmem_enabled_attr;
 /*
  * Mask of all large folio orders supported for file THP. Folios in a DAX
  * file is never split and the MAX_PAGECACHE_ORDER limit does not apply to
- * it.
+ * it.  Same to PFNMAPs where there's neither page* nor pagecache.
  */
-#define THP_ORDERS_ALL_FILE_DAX		\
+#define THP_ORDERS_ALL_SPECIAL		\
 	(BIT(PMD_ORDER) | BIT(PUD_ORDER))
 #define THP_ORDERS_ALL_FILE_DEFAULT	\
 	((BIT(MAX_PAGECACHE_ORDER + 1) - 1) & ~BIT(0))
@@ -87,7 +87,7 @@ extern struct kobj_attribute thpsize_shmem_enabled_attr;
  * Mask of all large folio orders supported for THP.
  */
 #define THP_ORDERS_ALL	\
-	(THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE_DAX | THP_ORDERS_ALL_FILE_DEFAULT)
+	(THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_SPECIAL | THP_ORDERS_ALL_FILE_DEFAULT)
 
 #define TVA_SMAPS		(1 << 0)	/* Will be used for procfs */
 #define TVA_IN_PF		(1 << 1)	/* Page fault handler */

mm/huge_memory.c

@@ -97,8 +97,8 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
 	/* Check the intersection of requested and supported orders. */
 	if (vma_is_anonymous(vma))
 		supported_orders = THP_ORDERS_ALL_ANON;
-	else if (vma_is_dax(vma))
-		supported_orders = THP_ORDERS_ALL_FILE_DAX;
+	else if (vma_is_special_huge(vma))
+		supported_orders = THP_ORDERS_ALL_SPECIAL;
 	else
 		supported_orders = THP_ORDERS_ALL_FILE_DEFAULT;