mm: make hugetlb mappings go through mm_get_unmapped_area_vmflags

Hugetlb mappings will no longer be special cased but rather go through the
generic mm_get_unmapped_area_vmflags function.  For that to happen, let us
remove the .get_unmapped_area from hugetlbfs_file_operations struct, and
hint __get_unmapped_area that it should not send hugetlb mappings through
thp_get_unmapped_area_vmflags but through mm_get_unmapped_area_vmflags.

Create also a function called hugetlb_mmap_check_and_align() where a
couple of safety checks are being done and the addr is aligned to the huge
page size.  Otherwise we will have to do this in every single function,
which duplicates quite a lot of code.

Link: https://lkml.kernel.org/r/20241007075037.267650-7-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 5cf3273..2c5f34e 100644 (file)
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -258,15 +258,23 @@ generic_hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
                        pgoff, flags);
 }
 
-#ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
-static unsigned long
-hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
-                         unsigned long len, unsigned long pgoff,
-                         unsigned long flags)
+unsigned long
+__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
+                           unsigned long len, unsigned long flags)
 {
-       return generic_hugetlb_get_unmapped_area(file, addr, len, pgoff, flags);
+       unsigned long addr0 = 0;
+       struct hstate *h = hstate_file(file);
+
+       if (len & ~huge_page_mask(h))
+               return -EINVAL;
+       if ((flags & MAP_FIXED) && prepare_hugepage_range(file, addr, len))
+               return -EINVAL;
+       if (addr)
+               addr0 = ALIGN(addr, huge_page_size(h));
+
+       return mm_get_unmapped_area_vmflags(current->mm, file, addr, len, pgoff,
+                                           flags, 0);
 }
-#endif
 
 /*
  * Someone wants to read @bytes from a HWPOISON hugetlb @page from @offset.
@@ -1300,7 +1308,7 @@ static const struct file_operations hugetlbfs_file_operations = {
        .read_iter              = hugetlbfs_read_iter,
        .mmap                   = hugetlbfs_file_mmap,
        .fsync                  = noop_fsync,
-       .get_unmapped_area      = hugetlb_get_unmapped_area,
+       .get_unmapped_area      = __hugetlb_get_unmapped_area,
        .llseek                 = default_llseek,
        .fallocate              = hugetlbfs_fallocate,
        .fop_flags              = FOP_HUGE_PAGES,

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 368d552..3a81b61 100644 (file)
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -546,11 +546,10 @@ static inline struct hstate *hstate_inode(struct inode *i)
 }
 #endif /* !CONFIG_HUGETLBFS */
 
-#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
-unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
-                                       unsigned long len, unsigned long pgoff,
-                                       unsigned long flags);
-#endif /* HAVE_ARCH_HUGETLB_UNMAPPED_AREA */
+unsigned long
+__generic_hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
+                                   unsigned long len, unsigned long pgoff,
+                                   unsigned long flags);
 
 unsigned long
 generic_hugetlb_get_unmapped_area(struct file *file, unsigned long addr,