mm: factor out VMA stack and heap checks

Patch series "mm: convert to vma_is_initial_heap/stack()", v3.

Add vma_is_initial_stack() and vma_is_initial_heap() helpers and use them
to simplify code.


This patch (of 4):

Factor out VMA stack and heap checks and name them vma_is_initial_stack()
and vma_is_initial_heap() for general use.

Link: https://lkml.kernel.org/r/20230728050043.59880-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20230728050043.59880-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@gmail.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/proc/task_mmu.c

@@ -236,21 +236,6 @@ static int do_maps_open(struct inode *inode, struct file *file,
 				sizeof(struct proc_maps_private));
 }
 
-/*
- * Indicate if the VMA is a stack for the given task; for
- * /proc/PID/maps that is the stack of the main task.
- */
-static int is_stack(struct vm_area_struct *vma)
-{
-	/*
-	 * We make no effort to guess what a given thread considers to be
-	 * its "stack".  It's not even well-defined for programs written
-	 * languages like Go.
-	 */
-	return vma->vm_start <= vma->vm_mm->start_stack &&
-		vma->vm_end >= vma->vm_mm->start_stack;
-}
-
 static void show_vma_header_prefix(struct seq_file *m,
 				   unsigned long start, unsigned long end,
 				   vm_flags_t flags, unsigned long long pgoff,
@@ -327,13 +312,12 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 			goto done;
 		}
 
-		if (vma->vm_start <= mm->brk &&
-		    vma->vm_end >= mm->start_brk) {
+		if (vma_is_initial_heap(vma)) {
 			name = "[heap]";
 			goto done;
 		}
 
-		if (is_stack(vma)) {
+		if (vma_is_initial_stack(vma)) {
 			name = "[stack]";
 			goto done;
 		}
@@ -1971,9 +1955,9 @@ static int show_numa_map(struct seq_file *m, void *v)
 	if (file) {
 		seq_puts(m, " file=");
 		seq_file_path(m, file, "\n\t= ");
-	} else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) {
+	} else if (vma_is_initial_heap(vma)) {
 		seq_puts(m, " heap");
-	} else if (is_stack(vma)) {
+	} else if (vma_is_initial_stack(vma)) {
 		seq_puts(m, " stack");
 	}
 

fs/proc/task_nommu.c

@@ -121,19 +121,6 @@ unsigned long task_statm(struct mm_struct *mm,
 	return size;
 }
 
-static int is_stack(struct vm_area_struct *vma)
-{
-	struct mm_struct *mm = vma->vm_mm;
-
-	/*
-	 * We make no effort to guess what a given thread considers to be
-	 * its "stack".  It's not even well-defined for programs written
-	 * languages like Go.
-	 */
-	return vma->vm_start <= mm->start_stack &&
-		vma->vm_end >= mm->start_stack;
-}
-
 /*
  * display a single VMA to a sequenced file
  */
@@ -171,7 +158,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
 	if (file) {
 		seq_pad(m, ' ');
 		seq_file_path(m, file, "");
-	} else if (mm && is_stack(vma)) {
+	} else if (mm && vma_is_initial_stack(vma)) {
 		seq_pad(m, ' ');
 		seq_puts(m, "[stack]");
 	}

include/linux/mm.h

@@ -833,6 +833,31 @@ static inline bool vma_is_anonymous(struct vm_area_struct *vma)
 	return !vma->vm_ops;
 }
 
+/*
+ * Indicate if the VMA is a heap for the given task; for
+ * /proc/PID/maps that is the heap of the main task.
+ */
+static inline bool vma_is_initial_heap(const struct vm_area_struct *vma)
+{
+       return vma->vm_start <= vma->vm_mm->brk &&
+		vma->vm_end >= vma->vm_mm->start_brk;
+}
+
+/*
+ * Indicate if the VMA is a stack for the given task; for
+ * /proc/PID/maps that is the stack of the main task.
+ */
+static inline bool vma_is_initial_stack(const struct vm_area_struct *vma)
+{
+	/*
+	 * We make no effort to guess what a given thread considers to be
+	 * its "stack".  It's not even well-defined for programs written
+	 * languages like Go.
+	 */
+       return vma->vm_start <= vma->vm_mm->start_stack &&
+	       vma->vm_end >= vma->vm_mm->start_stack;
+}
+
 static inline bool vma_is_temporary_stack(struct vm_area_struct *vma)
 {
 	int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);