mm: Add an apply_to_pfn_range interface

This is basically apply_to_page_range with added functionality:
Allocating missing parts of the page table becomes optional, which
means that the function can be guaranteed not to error if allocation
is disabled. Also passing of the closure struct and callback function
becomes different and more in line with how things are done elsewhere.

Finally we keep apply_to_page_range as a wrapper around apply_to_pfn_range

The reason for not using the page-walk code is that we want to perform
the page-walk on vmas pointing to an address space without requiring the
mmap_sem to be held rather than on vmas belonging to a process with the
mmap_sem held.

Notable changes since RFC:
Don't export apply_to_pfn range.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> #v1

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e8834ac32b7..3d06ce2a64af 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2675,6 +2675,16 @@ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
 extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
 			       unsigned long size, pte_fn_t fn, void *data);
 
+struct pfn_range_apply;
+typedef int (*pter_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
+			 struct pfn_range_apply *closure);
+struct pfn_range_apply {
+	struct mm_struct *mm;
+	pter_fn_t ptefn;
+	unsigned int alloc;
+};
+extern int apply_to_pfn_range(struct pfn_range_apply *closure,
+			      unsigned long address, unsigned long size);
 
 #ifdef CONFIG_PAGE_POISONING
 extern bool page_poisoning_enabled(void);