mm: userfaultfd: don't pass around both mm and vma

Quite a few userfaultfd functions took both mm and vma pointers as
arguments.  Since the mm is trivially accessible via vma->vm_mm, there's
no reason to pass both; it just needlessly extends the already long
argument list.

Get rid of the mm pointer, where possible, to shorten the argument list.

Link: https://lkml.kernel.org/r/20230314221250.682452-3-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 29 insertions, 32 deletions

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 874379ce271f..c3cc6cb04548 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -55,12 +55,13 @@ struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm,
  * This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem
  * and anon, and for both shared and private VMAs.
  */
-int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
+int mfill_atomic_install_pte(pmd_t *dst_pmd,
 			     struct vm_area_struct *dst_vma,
 			     unsigned long dst_addr, struct page *page,
 			     bool newly_allocated, bool wp_copy)
 {
 	int ret;
+	struct mm_struct *dst_mm = dst_vma->vm_mm;
 	pte_t _dst_pte, *dst_pte;
 	bool writable = dst_vma->vm_flags & VM_WRITE;
 	bool vm_shared = dst_vma->vm_flags & VM_SHARED;
@@ -127,8 +128,7 @@ out_unlock:
 	return ret;
 }
 
-static int mfill_atomic_pte_copy(struct mm_struct *dst_mm,
-				 pmd_t *dst_pmd,
+static int mfill_atomic_pte_copy(pmd_t *dst_pmd,
 				 struct vm_area_struct *dst_vma,
 				 unsigned long dst_addr,
 				 unsigned long src_addr,
@@ -190,10 +190,10 @@ static int mfill_atomic_pte_copy(struct mm_struct *dst_mm,
 	__SetPageUptodate(page);
 
 	ret = -ENOMEM;
-	if (mem_cgroup_charge(page_folio(page), dst_mm, GFP_KERNEL))
+	if (mem_cgroup_charge(page_folio(page), dst_vma->vm_mm, GFP_KERNEL))
 		goto out_release;
 
-	ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
+	ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
 				       page, true, wp_copy);
 	if (ret)
 		goto out_release;
@@ -204,8 +204,7 @@ out_release:
 	goto out;
 }
 
-static int mfill_atomic_pte_zeropage(struct mm_struct *dst_mm,
-				     pmd_t *dst_pmd,
+static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
 				     struct vm_area_struct *dst_vma,
 				     unsigned long dst_addr)
 {
@@ -217,7 +216,7 @@ static int mfill_atomic_pte_zeropage(struct mm_struct *dst_mm,
 
 	_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
 					 dst_vma->vm_page_prot));
-	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+	dst_pte = pte_offset_map_lock(dst_vma->vm_mm, dst_pmd, dst_addr, &ptl);
 	if (dst_vma->vm_file) {
 		/* the shmem MAP_PRIVATE case requires checking the i_size */
 		inode = dst_vma->vm_file->f_inode;
@@ -230,7 +229,7 @@ static int mfill_atomic_pte_zeropage(struct mm_struct *dst_mm,
 	ret = -EEXIST;
 	if (!pte_none(*dst_pte))
 		goto out_unlock;
-	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+	set_pte_at(dst_vma->vm_mm, dst_addr, dst_pte, _dst_pte);
 	/* No need to invalidate - it was non-present before */
 	update_mmu_cache(dst_vma, dst_addr, dst_pte);
 	ret = 0;
@@ -240,8 +239,7 @@ out_unlock:
 }
 
 /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */
-static int mfill_atomic_pte_continue(struct mm_struct *dst_mm,
-				     pmd_t *dst_pmd,
+static int mfill_atomic_pte_continue(pmd_t *dst_pmd,
 				     struct vm_area_struct *dst_vma,
 				     unsigned long dst_addr,
 				     bool wp_copy)
@@ -269,7 +267,7 @@ static int mfill_atomic_pte_continue(struct mm_struct *dst_mm,
 		goto out_release;
 	}
 
-	ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
+	ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
 				       page, false, wp_copy);
 	if (ret)
 		goto out_release;
@@ -310,7 +308,7 @@ static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
  * mfill_atomic processing for HUGETLB vmas.  Note that this routine is
  * called with mmap_lock held, it will release mmap_lock before returning.
  */
-static __always_inline ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm,
+static __always_inline ssize_t mfill_atomic_hugetlb(
 					      struct vm_area_struct *dst_vma,
 					      unsigned long dst_start,
 					      unsigned long src_start,
@@ -318,6 +316,7 @@ static __always_inline ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm,
 					      enum mcopy_atomic_mode mode,
 					      bool wp_copy)
 {
+	struct mm_struct *dst_mm = dst_vma->vm_mm;
 	int vm_shared = dst_vma->vm_flags & VM_SHARED;
 	ssize_t err;
 	pte_t *dst_pte;
@@ -411,7 +410,7 @@ retry:
 			goto out_unlock;
 		}
 
-		err = hugetlb_mfill_atomic_pte(dst_mm, dst_pte, dst_vma,
+		err = hugetlb_mfill_atomic_pte(dst_pte, dst_vma,
 					       dst_addr, src_addr, mode, &page,
 					       wp_copy);
 
@@ -463,17 +462,15 @@ out:
 }
 #else /* !CONFIG_HUGETLB_PAGE */
 /* fail at build time if gcc attempts to use this */
-extern ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm,
-				      struct vm_area_struct *dst_vma,
-				      unsigned long dst_start,
-				      unsigned long src_start,
-				      unsigned long len,
-				      enum mcopy_atomic_mode mode,
-				      bool wp_copy);
+extern ssize_t mfill_atomic_hugetlb(struct vm_area_struct *dst_vma,
+				    unsigned long dst_start,
+				    unsigned long src_start,
+				    unsigned long len,
+				    enum mcopy_atomic_mode mode,
+				    bool wp_copy);
 #endif /* CONFIG_HUGETLB_PAGE */
 
-static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
-						pmd_t *dst_pmd,
+static __always_inline ssize_t mfill_atomic_pte(pmd_t *dst_pmd,
 						struct vm_area_struct *dst_vma,
 						unsigned long dst_addr,
 						unsigned long src_addr,
@@ -484,7 +481,7 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
 	ssize_t err;
 
 	if (mode == MCOPY_ATOMIC_CONTINUE) {
-		return mfill_atomic_pte_continue(dst_mm, dst_pmd, dst_vma,
+		return mfill_atomic_pte_continue(dst_pmd, dst_vma,
 						 dst_addr, wp_copy);
 	}
 
@@ -500,14 +497,14 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
 	 */
 	if (!(dst_vma->vm_flags & VM_SHARED)) {
 		if (mode == MCOPY_ATOMIC_NORMAL)
-			err = mfill_atomic_pte_copy(dst_mm, dst_pmd, dst_vma,
+			err = mfill_atomic_pte_copy(dst_pmd, dst_vma,
 						    dst_addr, src_addr, page,
 						    wp_copy);
 		else
-			err = mfill_atomic_pte_zeropage(dst_mm, dst_pmd,
+			err = mfill_atomic_pte_zeropage(dst_pmd,
 						 dst_vma, dst_addr);
 	} else {
-		err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
+		err = shmem_mfill_atomic_pte(dst_pmd, dst_vma,
 					     dst_addr, src_addr,
 					     mode != MCOPY_ATOMIC_NORMAL,
 					     wp_copy, page);
@@ -588,7 +585,7 @@ retry:
 	 * If this is a HUGETLB vma, pass off to appropriate routine
 	 */
 	if (is_vm_hugetlb_page(dst_vma))
-		return  mfill_atomic_hugetlb(dst_mm, dst_vma, dst_start,
+		return  mfill_atomic_hugetlb(dst_vma, dst_start,
 					     src_start, len, mcopy_mode,
 					     wp_copy);
 
@@ -641,7 +638,7 @@ retry:
 		BUG_ON(pmd_none(*dst_pmd));
 		BUG_ON(pmd_trans_huge(*dst_pmd));
 
-		err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
+		err = mfill_atomic_pte(dst_pmd, dst_vma, dst_addr,
 				       src_addr, &page, mcopy_mode, wp_copy);
 		cond_resched();
 
@@ -710,7 +707,7 @@ ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start,
 			    mmap_changing, 0);
 }
 
-long uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma,
+long uffd_wp_range(struct vm_area_struct *dst_vma,
 		   unsigned long start, unsigned long len, bool enable_wp)
 {
 	unsigned int mm_cp_flags;
@@ -732,7 +729,7 @@ long uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma,
 	 */
 	if (!enable_wp && vma_wants_manual_pte_write_upgrade(dst_vma))
 		mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
-	tlb_gather_mmu(&tlb, dst_mm);
+	tlb_gather_mmu(&tlb, dst_vma->vm_mm);
 	ret = change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags);
 	tlb_finish_mmu(&tlb);
 
@@ -788,7 +785,7 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
 		_start = max(dst_vma->vm_start, start);
 		_end = min(dst_vma->vm_end, end);
 
-		err = uffd_wp_range(dst_mm, dst_vma, _start, _end - _start, enable_wp);
+		err = uffd_wp_range(dst_vma, _start, _end - _start, enable_wp);
 
 		/* Return 0 on success, <0 on failures */
 		if (err < 0)