Re: [PATCH 09/13] fs/proc/task_mmu: convert VMA flag tests to use vma_flags_t

[Lance Yang]

On Thu, Nov 05, 2026 at 09:31:00PM +0000, Lorenzo Stoakes (ARM) wrote:
>Replace use of the legacy vm_flags_t flags with vma_flags_t values where
>VMA flags are tested directly in /proc/$pid/[s]maps, pagemap, clear_refs
>and PROCMAP_QUERY.
>
>In replacing vm_flags_clear() (which takes the VMA write lock) with
>vma_clear_flags() (which does not) in clear_refs_write(), we explicitly
>write lock the VMA. The mmap write lock is already held at this point.
>
>The show_vma_header_prefix() and show_smap_vma_flags() output functions and
>the thp_vma_allowable_orders() call continue to use legacy flags for the
>time being.
>
>No functional change intended.
>
>Signed-off-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>
>---
> fs/proc/task_mmu.c | 43 ++++++++++++++++++++++---------------------
> 1 file changed, 22 insertions(+), 21 deletions(-)
>
>diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
>index 22361607020d..b6e8ef15e40e 100644
>--- a/fs/proc/task_mmu.c
>+++ b/fs/proc/task_mmu.c
>@@ -569,18 +569,18 @@ static struct vm_area_struct *query_matching_vma(struct proc_maps_locking_ctx *l
> 
> 	/* VMA permissions should satisfy query flags */
> 	if (flags & PROCMAP_QUERY_VMA_FLAGS) {
>-		u32 perm = 0;
>+		vma_flags_t perm = EMPTY_VMA_FLAGS;
> 
> 		if (flags & PROCMAP_QUERY_VMA_READABLE)
>-			perm |= VM_READ;
>+			vma_flags_set(&perm, VMA_READ_BIT);
> 		if (flags & PROCMAP_QUERY_VMA_WRITABLE)
>-			perm |= VM_WRITE;
>+			vma_flags_set(&perm, VMA_WRITE_BIT);
> 		if (flags & PROCMAP_QUERY_VMA_EXECUTABLE)
>-			perm |= VM_EXEC;
>+			vma_flags_set(&perm, VMA_EXEC_BIT);
> 		if (flags & PROCMAP_QUERY_VMA_SHARED)
>-			perm |= VM_MAYSHARE;
>+			vma_flags_set(&perm, VMA_MAYSHARE_BIT);
> 
>-		if ((vma->vm_flags & perm) != perm)
>+		if (!vma_test_all_mask(vma, perm))
> 			goto skip_vma;
> 	}
> 
>@@ -647,13 +647,13 @@ static int do_procmap_query(struct mm_struct *mm, void __user *uarg)
> 	karg.vma_end = vma->vm_end;
> 
> 	karg.vma_flags = 0;
>-	if (vma->vm_flags & VM_READ)
>+	if (vma_test(vma, VMA_READ_BIT))
> 		karg.vma_flags |= PROCMAP_QUERY_VMA_READABLE;
>-	if (vma->vm_flags & VM_WRITE)
>+	if (vma_test(vma, VMA_WRITE_BIT))
> 		karg.vma_flags |= PROCMAP_QUERY_VMA_WRITABLE;
>-	if (vma->vm_flags & VM_EXEC)
>+	if (vma_test(vma, VMA_EXEC_BIT))
> 		karg.vma_flags |= PROCMAP_QUERY_VMA_EXECUTABLE;
>-	if (vma->vm_flags & VM_MAYSHARE)
>+	if (vma_test(vma, VMA_MAYSHARE_BIT))
> 		karg.vma_flags |= PROCMAP_QUERY_VMA_SHARED;
> 
> 	karg.vma_page_size = vma_kernel_pagesize(vma);
>@@ -970,7 +970,7 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
> {
> 	struct mem_size_stats *mss = walk->private;
> 	struct vm_area_struct *vma = walk->vma;
>-	bool locked = !!(vma->vm_flags & VM_LOCKED);
>+	bool locked = vma_test(vma, VMA_LOCKED_BIT);
> 	struct page *page = NULL;
> 	bool present = false, young = false, dirty = false;
> 	pte_t ptent = ptep_get(pte);
>@@ -1017,7 +1017,7 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
> {
> 	struct mem_size_stats *mss = walk->private;
> 	struct vm_area_struct *vma = walk->vma;
>-	bool locked = !!(vma->vm_flags & VM_LOCKED);
>+	bool locked = vma_test(vma, VMA_LOCKED_BIT);
> 	struct page *page = NULL;
> 	bool present = false;
> 	struct folio *folio;
>@@ -1728,7 +1728,7 @@ static int clear_refs_test_walk(unsigned long start, unsigned long end,
> 	struct clear_refs_private *cp = walk->private;
> 	struct vm_area_struct *vma = walk->vma;
> 
>-	if (vma->vm_flags & VM_PFNMAP)
>+	if (vma_test(vma, VMA_PFNMAP_BIT))
> 		return 1;
> 
> 	/*
>@@ -1798,9 +1798,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
> 
> 		if (type == CLEAR_REFS_SOFT_DIRTY) {
> 			for_each_vma(vmi, vma) {
>-				if (!(vma->vm_flags & VM_SOFTDIRTY))
>+				if (!vma_test(vma, VMA_SOFTDIRTY_BIT))
> 					continue;
>-				vm_flags_clear(vma, VM_SOFTDIRTY);

vm_flags_clear() still warns on VM_SOFTDIRTY when pgtable_supports_soft_dirty()
is false. Did you mean to drop that?

(Vaguely recall you weren't too keen on that warn, though I could be wrong.)

Otherwise, LGTM!

Reviewed-by: Lance Yang <lance.yang@xxxxxxxxx>