mm: remove the vma linked list

Replace any vm_next use with vma_find().

Update free_pgtables(), unmap_vmas(), and zap_page_range() to use the
maple tree.

Use the new free_pgtables() and unmap_vmas() in do_mas_align_munmap().  At
the same time, alter the loop to be more compact.

Now that free_pgtables() and unmap_vmas() take a maple tree as an
argument, rearrange do_mas_align_munmap() to use the new tree to hold the
vmas to remove.

Remove __vma_link_list() and __vma_unlink_list() as they are exclusively
used to update the linked list

Drop linked list update from __insert_vm_struct().

Rework validation of tree as it was depending on the linked list.

Link: https://lkml.kernel.org/r/20220504011345.662299-52-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20220513141548.2019143-1-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mm.h

@@ -1873,8 +1873,9 @@ void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
 		  unsigned long size);
 void zap_page_range(struct vm_area_struct *vma, unsigned long address,
 		    unsigned long size);
-void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
-		unsigned long start, unsigned long end);
+void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
+		struct vm_area_struct *start_vma, unsigned long start,
+		unsigned long end);
 
 struct mmu_notifier_range;
 

include/linux/mm_types.h

@@ -403,8 +403,6 @@ struct vm_area_struct {
 	unsigned long vm_end;		/* The first byte after our end address
 					   within vm_mm. */
 
-	/* linked list of VM areas per task, sorted by address */
-	struct vm_area_struct *vm_next, *vm_prev;
 	struct mm_struct *vm_mm;	/* The address space we belong to. */
 
 	/*
@@ -468,7 +466,6 @@ struct vm_area_struct {
 struct kioctx_table;
 struct mm_struct {
 	struct {
-		struct vm_area_struct *mmap;		/* list of VMAs */
 		struct maple_tree mm_mt;
 #ifdef CONFIG_MMU
 		unsigned long (*get_unmapped_area) (struct file *filp,
@@ -483,7 +480,6 @@ struct mm_struct {
 		unsigned long mmap_compat_legacy_base;
 #endif
 		unsigned long task_size;	/* size of task vm space */
-		unsigned long highest_vm_end;	/* highest vma end address */
 		pgd_t * pgd;
 
 #ifdef CONFIG_MEMBARRIER

kernel/fork.c

@@ -474,7 +474,6 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
 		 */
 		*new = data_race(*orig);
 		INIT_LIST_HEAD(&new->anon_vma_chain);
-		new->vm_next = new->vm_prev = NULL;
 		dup_anon_vma_name(orig, new);
 	}
 	return new;
@@ -579,7 +578,7 @@ static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
 static __latent_entropy int dup_mmap(struct mm_struct *mm,
 					struct mm_struct *oldmm)
 {
-	struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
+	struct vm_area_struct *mpnt, *tmp;
 	int retval;
 	unsigned long charge = 0;
 	MA_STATE(old_mas, &oldmm->mm_mt, 0, 0);
@@ -606,18 +605,11 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 	mm->exec_vm = oldmm->exec_vm;
 	mm->stack_vm = oldmm->stack_vm;
 
-	pprev = &mm->mmap;
 	retval = ksm_fork(mm, oldmm);
 	if (retval)
 		goto out;
 	khugepaged_fork(mm, oldmm);
 
-	retval = mas_expected_entries(&mas, oldmm->map_count);
-	if (retval)
-		goto out;
-
-	prev = NULL;
-
 	retval = mas_expected_entries(&mas, oldmm->map_count);
 	if (retval)
 		goto out;
@@ -689,14 +681,6 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 		if (is_vm_hugetlb_page(tmp))
 			reset_vma_resv_huge_pages(tmp);
 
-		/*
-		 * Link in the new vma and copy the page table entries.
-		 */
-		*pprev = tmp;
-		pprev = &tmp->vm_next;
-		tmp->vm_prev = prev;
-		prev = tmp;
-
 		/* Link the vma into the MT */
 		mas.index = tmp->vm_start;
 		mas.last = tmp->vm_end - 1;
@@ -1119,7 +1103,6 @@ static void mm_init_uprobes_state(struct mm_struct *mm)
 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 	struct user_namespace *user_ns)
 {
-	mm->mmap = NULL;
 	mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
 	mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
 	atomic_set(&mm->mm_users, 1);

mm/debug.c

@@ -139,13 +139,11 @@ EXPORT_SYMBOL(dump_page);
 
 void dump_vma(const struct vm_area_struct *vma)
 {
-	pr_emerg("vma %px start %px end %px\n"
-		"next %px prev %px mm %px\n"
+	pr_emerg("vma %px start %px end %px mm %px\n"
 		"prot %lx anon_vma %px vm_ops %px\n"
 		"pgoff %lx file %px private_data %px\n"
 		"flags: %#lx(%pGv)\n",
-		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
-		vma->vm_prev, vma->vm_mm,
+		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_mm,
 		(unsigned long)pgprot_val(vma->vm_page_prot),
 		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 		vma->vm_file, vma->vm_private_data,
@@ -155,11 +153,11 @@ EXPORT_SYMBOL(dump_vma);
 
 void dump_mm(const struct mm_struct *mm)
 {
-	pr_emerg("mm %px mmap %px task_size %lu\n"
+	pr_emerg("mm %px task_size %lu\n"
 #ifdef CONFIG_MMU
 		"get_unmapped_area %px\n"
 #endif
-		"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
+		"mmap_base %lu mmap_legacy_base %lu\n"
 		"pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 		"hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 		"pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
@@ -183,11 +181,11 @@ void dump_mm(const struct mm_struct *mm)
 		"tlb_flush_pending %d\n"
 		"def_flags: %#lx(%pGv)\n",
 
-		mm, mm->mmap, mm->task_size,
+		mm, mm->task_size,
 #ifdef CONFIG_MMU
 		mm->get_unmapped_area,
 #endif
-		mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
+		mm->mmap_base, mm->mmap_legacy_base,
 		mm->pgd, atomic_read(&mm->mm_users),
 		atomic_read(&mm->mm_count),
 		mm_pgtables_bytes(mm),

mm/internal.h

@@ -84,8 +84,9 @@ void folio_rotate_reclaimable(struct folio *folio);
 bool __folio_end_writeback(struct folio *folio);
 void deactivate_file_folio(struct folio *folio);
 
-void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
-		unsigned long floor, unsigned long ceiling);
+void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
+		   struct vm_area_struct *start_vma, unsigned long floor,
+		   unsigned long ceiling);
 void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte);
 
 struct zap_details;
@@ -479,9 +480,6 @@ static inline bool is_data_mapping(vm_flags_t flags)
 }
 
 /* mm/util.c */
-void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
-		struct vm_area_struct *prev);
-void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma);
 struct anon_vma *folio_anon_vma(struct folio *folio);
 
 #ifdef CONFIG_MMU

mm/memory.c

@@ -402,12 +402,21 @@ void free_pgd_range(struct mmu_gather *tlb,
 	} while (pgd++, addr = next, addr != end);
 }
 
-void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
-		unsigned long floor, unsigned long ceiling)
+void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
+		   struct vm_area_struct *vma, unsigned long floor,
+		   unsigned long ceiling)
 {
-	while (vma) {
-		struct vm_area_struct *next = vma->vm_next;
+	MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
+
+	do {
 		unsigned long addr = vma->vm_start;
+		struct vm_area_struct *next;
+
+		/*
+		 * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
+		 * be 0.  This will underflow and is okay.
+		 */
+		next = mas_find(&mas, ceiling - 1);
 
 		/*
 		 * Hide vma from rmap and truncate_pagecache before freeing
@@ -426,15 +435,15 @@ void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 			       && !is_vm_hugetlb_page(next)) {
 				vma = next;
-				next = vma->vm_next;
+				next = mas_find(&mas, ceiling - 1);
 				unlink_anon_vmas(vma);
 				unlink_file_vma(vma);
 			}
 			free_pgd_range(tlb, addr, vma->vm_end,
 				floor, next ? next->vm_start : ceiling);
 		}
 		vma = next;
-	}
+	} while (vma);
 }
 
 void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
@@ -1705,7 +1714,7 @@ static void unmap_single_vma(struct mmu_gather *tlb,
  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
  * drops the lock and schedules.
  */
-void unmap_vmas(struct mmu_gather *tlb,
+void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
 		struct vm_area_struct *vma, unsigned long start_addr,
 		unsigned long end_addr)
 {
@@ -1715,12 +1724,14 @@ void unmap_vmas(struct mmu_gather *tlb,
 		/* Careful - we need to zap private pages too! */
 		.even_cows = true,
 	};
+	MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
 
 	mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
 				start_addr, end_addr);
 	mmu_notifier_invalidate_range_start(&range);
-	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
+	do {
 		unmap_single_vma(tlb, vma, start_addr, end_addr, &details);
+	} while ((vma = mas_find(&mas, end_addr - 1)) != NULL);
 	mmu_notifier_invalidate_range_end(&range);
 }
 
@@ -1735,17 +1746,21 @@ void unmap_vmas(struct mmu_gather *tlb,
 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
 		unsigned long size)
 {
+	struct maple_tree *mt = &vma->vm_mm->mm_mt;
+	unsigned long end = start + size;
 	struct mmu_notifier_range range;
 	struct mmu_gather tlb;
+	MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
 
 	lru_add_drain();
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
 				start, start + size);
 	tlb_gather_mmu(&tlb, vma->vm_mm);
 	update_hiwater_rss(vma->vm_mm);
 	mmu_notifier_invalidate_range_start(&range);
-	for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next)
+	do {
 		unmap_single_vma(&tlb, vma, start, range.end, NULL);
+	} while ((vma = mas_find(&mas, end - 1)) != NULL);
 	mmu_notifier_invalidate_range_end(&range);
 	tlb_finish_mmu(&tlb);
 }