ipc/shm, mm: drop do_vma_munmap()

The do_vma_munmap() wrapper existed for callers that didn't have a vma
iterator and needed to check the vma mseal status prior to calling the
underlying munmap().  All callers now use a vma iterator and since the
mseal check has been moved to do_vmi_align_munmap() and the vmas are
aligned, this function can just be called instead.

do_vmi_align_munmap() can no longer be static as ipc/shm is using it and
it is exported via the mm.h header.

Link: https://lkml.kernel.org/r/20240830040101.822209-19-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Bert Karwatzki <spasswolf@web.de>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mm.h

@@ -3287,14 +3287,14 @@ extern unsigned long do_mmap(struct file *file, unsigned long addr,
 extern int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
 			 unsigned long start, size_t len, struct list_head *uf,
 			 bool unlock);
+int do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
+		    struct mm_struct *mm, unsigned long start,
+		    unsigned long end, struct list_head *uf, bool unlock);
 extern int do_munmap(struct mm_struct *, unsigned long, size_t,
 		     struct list_head *uf);
 extern int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior);
 
 #ifdef CONFIG_MMU
-extern int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
-			 unsigned long start, unsigned long end,
-			 struct list_head *uf, bool unlock);
 extern int __mm_populate(unsigned long addr, unsigned long len,
 			 int ignore_errors);
 static inline void mm_populate(unsigned long addr, unsigned long len)

ipc/shm.c

@@ -1778,8 +1778,8 @@ long ksys_shmdt(char __user *shmaddr)
 			 */
 			file = vma->vm_file;
 			size = i_size_read(file_inode(vma->vm_file));
-			do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
+			do_vmi_align_munmap(&vmi, vma, mm, vma->vm_start,
-				      NULL, false);
+					    vma->vm_end, NULL, false);
 			/*
 			 * We discovered the size of the shm segment, so
 			 * break out of here and fall through to the next
@@ -1803,8 +1803,8 @@ long ksys_shmdt(char __user *shmaddr)
 		if ((vma->vm_ops == &shm_vm_ops) &&
 		    ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
 		    (vma->vm_file == file)) {
-			do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
+			do_vmi_align_munmap(&vmi, vma, mm, vma->vm_start,
-				      NULL, false);
+					    vma->vm_end, NULL, false);
 		}
 
 		vma = vma_next(&vmi);

mm/mmap.c

@@ -169,11 +169,12 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 			goto out; /* mapping intersects with an existing non-brk vma. */
 		/*
 		 * mm->brk must be protected by write mmap_lock.
-		 * do_vma_munmap() will drop the lock on success,  so update it
+		 * do_vmi_align_munmap() will drop the lock on success,  so
-		 * before calling do_vma_munmap().
+		 * update it before calling do_vma_munmap().
 		 */
 		mm->brk = brk;
-		if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true))
+		if (do_vmi_align_munmap(&vmi, brkvma, mm, newbrk, oldbrk, &uf,
+					/* unlock = */ true))
 			goto out;
 
 		goto success_unlocked;
@@ -1479,9 +1480,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		vma->vm_file = get_file(file);
 		/*
 		 * call_mmap() may map PTE, so ensure there are no existing PTEs
-		 * call the vm_ops close function if one exists.
+		 * and call the vm_ops close function if one exists.
 		 */
-		vms_clean_up_area(&vms, &mas_detach, true);
+		vms_clean_up_area(&vms, &mas_detach);
 		error = call_mmap(file, vma);
 		if (error)
 			goto unmap_and_free_vma;
@@ -1744,28 +1745,6 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 	return ret;
 }
 
-/*
- * do_vma_munmap() - Unmap a full or partial vma.
- * @vmi: The vma iterator pointing at the vma
- * @vma: The first vma to be munmapped
- * @start: the start of the address to unmap
- * @end: The end of the address to unmap
- * @uf: The userfaultfd list_head
- * @unlock: Drop the lock on success
- *
- * unmaps a VMA mapping when the vma iterator is already in position.
- * Does not handle alignment.
- *
- * Return: 0 on success drops the lock of so directed, error on failure and will
- * still hold the lock.
- */
-int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		unsigned long start, unsigned long end, struct list_head *uf,
-		bool unlock)
-{
-	return do_vmi_align_munmap(vmi, vma, vma->vm_mm, start, end, uf, unlock);
-}
-
 /*
  * do_brk_flags() - Increase the brk vma if the flags match.
  * @vmi: The vma iterator

mm/vma.c

@@ -658,8 +658,8 @@ static inline void vms_clear_ptes(struct vma_munmap_struct *vms,
 	 */
 	mas_set(mas_detach, 1);
 	lru_add_drain();
-	tlb_gather_mmu(&tlb, vms->mm);
+	tlb_gather_mmu(&tlb, vms->vma->vm_mm);
-	update_hiwater_rss(vms->mm);
+	update_hiwater_rss(vms->vma->vm_mm);
 	unmap_vmas(&tlb, mas_detach, vms->vma, vms->start, vms->end,
 		   vms->vma_count, mm_wr_locked);
 
@@ -672,14 +672,14 @@ static inline void vms_clear_ptes(struct vma_munmap_struct *vms,
 }
 
 void vms_clean_up_area(struct vma_munmap_struct *vms,
-		struct ma_state *mas_detach, bool mm_wr_locked)
+		struct ma_state *mas_detach)
 {
 	struct vm_area_struct *vma;
 
 	if (!vms->nr_pages)
 		return;
 
-	vms_clear_ptes(vms, mas_detach, mm_wr_locked);
+	vms_clear_ptes(vms, mas_detach, true);
 	mas_set(mas_detach, 0);
 	mas_for_each(mas_detach, vma, ULONG_MAX)
 		if (vma->vm_ops && vma->vm_ops->close)
@@ -702,7 +702,7 @@ void vms_complete_munmap_vmas(struct vma_munmap_struct *vms,
 	struct vm_area_struct *vma;
 	struct mm_struct *mm;
 
-	mm = vms->mm;
+	mm = current->mm;
 	mm->map_count -= vms->vma_count;
 	mm->locked_vm -= vms->locked_vm;
 	if (vms->unlock)
@@ -770,7 +770,7 @@ int vms_gather_munmap_vmas(struct vma_munmap_struct *vms,
 		 * its limit temporarily, to help free resources as expected.
 		 */
 		if (vms->end < vms->vma->vm_end &&
-		    vms->mm->map_count >= sysctl_max_map_count)
+		    vms->vma->vm_mm->map_count >= sysctl_max_map_count)
 			goto map_count_exceeded;
 
 		/* Don't bother splitting the VMA if we can't unmap it anyway */

mm/vma.h

@@ -31,7 +31,6 @@ struct unlink_vma_file_batch {
  */
 struct vma_munmap_struct {
 	struct vma_iterator *vmi;
-	struct mm_struct *mm;
 	struct vm_area_struct *vma;     /* The first vma to munmap */
 	struct vm_area_struct *prev;    /* vma before the munmap area */
 	struct vm_area_struct *next;    /* vma after the munmap area */
@@ -114,7 +113,6 @@ static inline void init_vma_munmap(struct vma_munmap_struct *vms,
 		unsigned long start, unsigned long end, struct list_head *uf,
 		bool unlock)
 {
-	vms->mm = current->mm;
 	vms->vmi = vmi;
 	vms->vma = vma;
 	if (vma) {
@@ -142,7 +140,7 @@ void vms_complete_munmap_vmas(struct vma_munmap_struct *vms,
 		struct ma_state *mas_detach);
 
 void vms_clean_up_area(struct vma_munmap_struct *vms,
-		struct ma_state *mas_detach, bool mm_wr_locked);
+		struct ma_state *mas_detach);
 
 /*
  * reattach_vmas() - Undo any munmap work and free resources