[v2,1/4] mm: factor out VMA stack and heap checks

Commit Message

Kefeng Wang July 19, 2023, 7:51 a.m. UTC

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

Cc: Christian Göttsche <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Signed-off-by: Kefeng Wang <[e-mail]>
---
 fs/proc/task_mmu.c   | 24 ++++--------------------
 fs/proc/task_nommu.c | 15 +--------------
 include/linux/mm.h   | 21 +++++++++++++++++++++
 3 files changed, 26 insertions(+), 34 deletions(-)

Comments

David Hildenbrand July 19, 2023, 8:18 a.m. UTC | #1

On 19.07.23 09:51, Kefeng Wang wrote:
> Factor out VMA stack and heap checks and name them
> vma_is_initial_stack() and vma_is_initial_heap() for
> general use.
> 
> Cc: Christian Göttsche <[e-mail]>
> Cc: David Hildenbrand <[e-mail]>
> Signed-off-by: Kefeng Wang <[e-mail]>
> ---


[...]

> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 2dd73e4f3d8e..51f8c573db74 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -822,6 +822,27 @@ static inline bool vma_is_anonymous(struct vm_area_struct *vma)
>   	return !vma->vm_ops;
>   }
>   

Worth adding a similar comment like for vma_is_initial_stack() ?

> +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);

Reviewed-by: David Hildenbrand <[e-mail]>

Patch

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 507cd4e59d07..bf25178ae66a 100644
--- a/fs/proc/task_mmu.c
+++ b/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");
 	}
 
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 2c8b62265981..a8ac0dd8041e 100644
--- a/fs/proc/task_nommu.c
+++ b/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]");
 	}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2dd73e4f3d8e..51f8c573db74 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -822,6 +822,27 @@  static inline bool vma_is_anonymous(struct vm_area_struct *vma)
 	return !vma->vm_ops;
 }
 
+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);