[PATCHv2, RFC 21/30] x86-64, mm: proper alignment mappings with hugepages

[Kirill A. Shutemov]

From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>

Make arch_get_unmapped_area() return unmapped area aligned to HPAGE_MASK
if the file mapping can have huge pages.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/sys_x86_64.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index dbded5a..4e20cd5 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -15,6 +15,7 @@
 #include <linux/random.h>
 #include <linux/uaccess.h>
 #include <linux/elf.h>
+#include <linux/pagemap.h>
 
 #include <asm/ia32.h>
 #include <asm/syscalls.h>
@@ -135,7 +136,11 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.length = len;
 	info.low_limit = begin;
 	info.high_limit = end;
-	info.align_mask = filp ? get_align_mask() : 0;
+	if (filp)
+		info.align_mask = mapping_can_have_hugepages(filp->f_mapping) ?
+			PAGE_MASK & ~HPAGE_MASK : get_align_mask();
+	else
+		info.align_mask = 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
 	return vm_unmapped_area(&info);
 }
@@ -174,7 +179,11 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.length = len;
 	info.low_limit = PAGE_SIZE;
 	info.high_limit = mm->mmap_base;
-	info.align_mask = filp ? get_align_mask() : 0;
+	if (filp)
+		info.align_mask = mapping_can_have_hugepages(filp->f_mapping) ?
+			PAGE_MASK & ~HPAGE_MASK : get_align_mask();
+	else
+		info.align_mask = 0;
 	info.align_offset = pgoff << PAGE_SHIFT;
 	addr = vm_unmapped_area(&info);
 	if (!(addr & ~PAGE_MASK))
-- 
1.7.10.4

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