hugetlb: use vmf_anon_prepare() instead of anon_vma_prepare()

hugetlb_no_page() and hugetlb_wp() call anon_vma_prepare().  In
preparation for hugetlb to safely handle faults under the VMA lock, use
vmf_anon_prepare() here instead.

Additionally, passing hugetlb_wp() the vm_fault struct from
hugetlb_fault() works toward cleaning up the hugetlb code and function
stack.

Link: https://lkml.kernel.org/r/20240221234732.187629-5-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index fa695e71152cdd4579257d0e600f8bcf02e4cd70..5e2e4612d458fcf4ddd9807e952a7db4b2c29477 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5851,7 +5851,8 @@ static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
  */
 static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
                       unsigned long address, pte_t *ptep, unsigned int flags,
-                      struct folio *pagecache_folio, spinlock_t *ptl)
+                      struct folio *pagecache_folio, spinlock_t *ptl,
+                      struct vm_fault *vmf)
 {
        const bool unshare = flags & FAULT_FLAG_UNSHARE;
        pte_t pte = huge_ptep_get(ptep);
@@ -5985,10 +5986,9 @@ retry_avoidcopy:
         * When the original hugepage is shared one, it does not have
         * anon_vma prepared.
         */
-       if (unlikely(anon_vma_prepare(vma))) {
-               ret = VM_FAULT_OOM;
+       ret = vmf_anon_prepare(vmf);
+       if (unlikely(ret))
                goto out_release_all;
-       }
 
        if (copy_user_large_folio(new_folio, old_folio, address, vma)) {
                ret = VM_FAULT_HWPOISON_LARGE;
@@ -6228,10 +6228,10 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
                        new_pagecache_folio = true;
                } else {
                        folio_lock(folio);
-                       if (unlikely(anon_vma_prepare(vma))) {
-                               ret = VM_FAULT_OOM;
+
+                       ret = vmf_anon_prepare(vmf);
+                       if (unlikely(ret))
                                goto backout_unlocked;
-                       }
                        anon_rmap = 1;
                }
        } else {
@@ -6298,7 +6298,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
        hugetlb_count_add(pages_per_huge_page(h), mm);
        if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
                /* Optimization, do the COW without a second fault */
-               ret = hugetlb_wp(mm, vma, address, ptep, flags, folio, ptl);
+               ret = hugetlb_wp(mm, vma, address, ptep, flags, folio, ptl, vmf);
        }
 
        spin_unlock(ptl);
@@ -6521,7 +6521,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        if (flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
                if (!huge_pte_write(entry)) {
                        ret = hugetlb_wp(mm, vma, address, ptep, flags,
-                                        pagecache_folio, ptl);
+                                        pagecache_folio, ptl, &vmf);
                        goto out_put_page;
                } else if (likely(flags & FAULT_FLAG_WRITE)) {
                        entry = huge_pte_mkdirty(entry);