[RFC PATCH 01/15] mm/vmalloc: add new 'alignment' field for vm_struct structure

[Roman Penyaev]

I need a new alignment field for vm area in order to reallocate
previously allocated area with the same alignment.

Patch for a new vrealloc() call will follow and this new call
I want to keep as simple as possible, thus not to provide dozens
of variants, like vrealloc_user(), which cares about alignment.

Current changes are just preparations.

Worth to mention, that on archs were unsigned long is 64 bit
this new field does not bloat vm_struct, because originally
there was a padding between nr_pages and phys_addr.

Signed-off-by: Roman Penyaev <rpenyaev@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 include/linux/vmalloc.h |  1 +
 mm/vmalloc.c            | 10 ++++++----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 398e9c95cd61..78210aa0bb43 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -38,6 +38,7 @@ struct vm_struct {
 	unsigned long		flags;
 	struct page		**pages;
 	unsigned int		nr_pages;
+	unsigned int		alignment;
 	phys_addr_t		phys_addr;
 	const void		*caller;
 };
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e83961767dc1..4851b4a67f55 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1347,12 +1347,14 @@ int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page **pages)
 EXPORT_SYMBOL_GPL(map_vm_area);
 
 static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
-			      unsigned long flags, const void *caller)
+			     unsigned int align, unsigned long flags,
+			     const void *caller)
 {
 	spin_lock(&vmap_area_lock);
 	vm->flags = flags;
 	vm->addr = (void *)va->va_start;
 	vm->size = va->va_end - va->va_start;
+	vm->alignment = align;
 	vm->caller = caller;
 	va->vm = vm;
 	va->flags |= VM_VM_AREA;
@@ -1399,7 +1401,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
 		return NULL;
 	}
 
-	setup_vmalloc_vm(area, va, flags, caller);
+	setup_vmalloc_vm(area, va, align, flags, caller);
 
 	return area;
 }
@@ -2601,8 +2603,8 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
 
 	/* insert all vm's */
 	for (area = 0; area < nr_vms; area++)
-		setup_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
-				 pcpu_get_vm_areas);
+		setup_vmalloc_vm(vms[area], vas[area], align,
+				 VM_ALLOC, pcpu_get_vm_areas);
 
 	kfree(vas);
 	return vms;
-- 
2.19.1