Subject: [RFC PATCH RESEND 03/28] mm: introduce __find_vma to be used without mmap_lock protection

From: Suren Baghdasaryan <[email-masked]>
Date: Thu, 1 Sep 2022 10:34:51 -0700

Add __find_vma function to be used for VMA lookup under rcu protection.

Signed-off-by: Suren Baghdasaryan <[email-masked]>
---
 drivers/gpu/drm/i915/i915_gpu_error.c | 4 ++--
 include/linux/mm.h                    | 9 ++++++++-
 mm/mmap.c                             | 6 ++----
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 32e92651ef7c..fc94985c95c8 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -507,7 +507,7 @@ static void error_print_context(struct drm_i915_error_state_buf *m,
 }
 
 static struct i915_vma_coredump *
-__find_vma(struct i915_vma_coredump *vma, const char *name)
+__i915_find_vma(struct i915_vma_coredump *vma, const char *name)
 {
 	while (vma) {
 		if (strcmp(vma->name, name) == 0)
@@ -521,7 +521,7 @@ __find_vma(struct i915_vma_coredump *vma, const char *name)
 struct i915_vma_coredump *
 intel_gpu_error_find_batch(const struct intel_engine_coredump *ee)
 {
-	return __find_vma(ee->vma, "batch");
+	return __i915_find_vma(ee->vma, "batch");
 }
 
 static void error_print_engine(struct drm_i915_error_state_buf *m,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 21f8b27bd9fd..7d322a979455 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2712,7 +2712,14 @@ extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
 #endif
 
 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
-extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);
+extern struct vm_area_struct *__find_vma(struct mm_struct *mm, unsigned long addr);
+static inline
+struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+{
+	mmap_assert_locked(mm);
+	return __find_vma(mm, addr);
+}
+
 extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
 					     struct vm_area_struct **pprev);
 
diff --git a/mm/mmap.c b/mm/mmap.c
index 9d780f415be3..693e6776be39 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2250,12 +2250,11 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 EXPORT_SYMBOL(get_unmapped_area);
 
 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
-struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+struct vm_area_struct *__find_vma(struct mm_struct *mm, unsigned long addr)
 {
 	struct rb_node *rb_node;
 	struct vm_area_struct *vma;
 
-	mmap_assert_locked(mm);
 	/* Check the cache first. */
 	vma = vmacache_find(mm, addr);
 	if (likely(vma))
@@ -2281,8 +2280,7 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 		vmacache_update(addr, vma);
 	return vma;
 }
-
-EXPORT_SYMBOL(find_vma);
+EXPORT_SYMBOL(__find_vma);
 
 /*
  * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
-- 
2.37.2.789.g6183377224-goog