Revert "binder: switch alloc->mutex to spinlock_t"

This reverts commit 7710e2cca3.

In preparation for concurrent page installations, restore the original
alloc->mutex which will serialize zap_page_range_single() against page
installations in subsequent patches (instead of the mmap_sem).

Resolved trivial conflicts with commit 2c10a20f5e ("binder_alloc: Fix
sleeping function called from invalid context") and commit da0c02516c
("mm/list_lru: simplify the list_lru walk callback function").

Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-2-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder_alloc.c

@@ -169,9 +169,9 @@ struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
 {
 	struct binder_buffer *buffer;
 
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 	return buffer;
 }
 
@@ -597,10 +597,10 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 	if (!next)
 		return ERR_PTR(-ENOMEM);
 
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	buffer = binder_alloc_new_buf_locked(alloc, next, size, is_async);
 	if (IS_ERR(buffer)) {
-		spin_unlock(&alloc->lock);
+		mutex_unlock(&alloc->mutex);
 		goto out;
 	}
 
@@ -608,7 +608,7 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 	buffer->offsets_size = offsets_size;
 	buffer->extra_buffers_size = extra_buffers_size;
 	buffer->pid = current->tgid;
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 
 	ret = binder_install_buffer_pages(alloc, buffer, size);
 	if (ret) {
@@ -785,17 +785,17 @@ void binder_alloc_free_buf(struct binder_alloc *alloc,
 	 * We could eliminate the call to binder_alloc_clear_buf()
 	 * from binder_alloc_deferred_release() by moving this to
 	 * binder_free_buf_locked(). However, that could
-	 * increase contention for the alloc->lock if clear_on_free
-	 * is used frequently for large buffers. This lock is not
+	 * increase contention for the alloc mutex if clear_on_free
+	 * is used frequently for large buffers. The mutex is not
 	 * needed for correctness here.
 	 */
 	if (buffer->clear_on_free) {
 		binder_alloc_clear_buf(alloc, buffer);
 		buffer->clear_on_free = false;
 	}
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	binder_free_buf_locked(alloc, buffer);
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 }
 
 /**
@@ -893,7 +893,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 	struct binder_buffer *buffer;
 
 	buffers = 0;
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	BUG_ON(alloc->vma);
 
 	while ((n = rb_first(&alloc->allocated_buffers))) {
@@ -940,7 +940,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 			page_count++;
 		}
 	}
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 	kvfree(alloc->pages);
 	if (alloc->mm)
 		mmdrop(alloc->mm);
@@ -964,7 +964,7 @@ void binder_alloc_print_allocated(struct seq_file *m,
 	struct binder_buffer *buffer;
 	struct rb_node *n;
 
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	for (n = rb_first(&alloc->allocated_buffers); n; n = rb_next(n)) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
 		seq_printf(m, "  buffer %d: %lx size %zd:%zd:%zd %s\n",
@@ -974,7 +974,7 @@ void binder_alloc_print_allocated(struct seq_file *m,
 			   buffer->extra_buffers_size,
 			   buffer->transaction ? "active" : "delivered");
 	}
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 }
 
 /**
@@ -991,7 +991,7 @@ void binder_alloc_print_pages(struct seq_file *m,
 	int lru = 0;
 	int free = 0;
 
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	/*
 	 * Make sure the binder_alloc is fully initialized, otherwise we might
 	 * read inconsistent state.
@@ -1007,7 +1007,7 @@ void binder_alloc_print_pages(struct seq_file *m,
 				lru++;
 		}
 	}
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
 	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
 }
@@ -1023,10 +1023,10 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
 	struct rb_node *n;
 	int count = 0;
 
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
 		count++;
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 	return count;
 }
 
@@ -1070,8 +1070,8 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 		goto err_mmget;
 	if (!mmap_read_trylock(mm))
 		goto err_mmap_read_lock_failed;
-	if (!spin_trylock(&alloc->lock))
-		goto err_get_alloc_lock_failed;
+	if (!mutex_trylock(&alloc->mutex))
+		goto err_get_alloc_mutex_failed;
 	if (!page->page_ptr)
 		goto err_page_already_freed;
 
@@ -1090,7 +1090,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 	trace_binder_unmap_kernel_end(alloc, index);
 
 	list_lru_isolate(lru, item);
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 	spin_unlock(&lru->lock);
 
 	if (vma) {
@@ -1109,8 +1109,8 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
 
 err_invalid_vma:
 err_page_already_freed:
-	spin_unlock(&alloc->lock);
-err_get_alloc_lock_failed:
+	mutex_unlock(&alloc->mutex);
+err_get_alloc_mutex_failed:
 	mmap_read_unlock(mm);
 err_mmap_read_lock_failed:
 	mmput_async(mm);
@@ -1145,7 +1145,7 @@ void binder_alloc_init(struct binder_alloc *alloc)
 	alloc->pid = current->group_leader->pid;
 	alloc->mm = current->mm;
 	mmgrab(alloc->mm);
-	spin_lock_init(&alloc->lock);
+	mutex_init(&alloc->mutex);
 	INIT_LIST_HEAD(&alloc->buffers);
 }
 

drivers/android/binder_alloc.h

@@ -9,7 +9,7 @@
 #include <linux/rbtree.h>
 #include <linux/list.h>
 #include <linux/mm.h>
-#include <linux/spinlock.h>
+#include <linux/rtmutex.h>
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
 #include <linux/list_lru.h>
@@ -72,7 +72,7 @@ struct binder_lru_page {
 
 /**
  * struct binder_alloc - per-binder proc state for binder allocator
- * @lock:               protects binder_alloc fields
+ * @mutex:              protects binder_alloc fields
  * @vma:                vm_area_struct passed to mmap_handler
  *                      (invariant after mmap)
  * @mm:                 copy of task->mm (invariant after open)
@@ -96,7 +96,7 @@ struct binder_lru_page {
  * struct binder_buffer objects used to track the user buffers
  */
 struct binder_alloc {
-	spinlock_t lock;
+	struct mutex mutex;
 	struct vm_area_struct *vma;
 	struct mm_struct *mm;
 	unsigned long buffer;
@@ -153,9 +153,9 @@ binder_alloc_get_free_async_space(struct binder_alloc *alloc)
 {
 	size_t free_async_space;
 
-	spin_lock(&alloc->lock);
+	mutex_lock(&alloc->mutex);
 	free_async_space = alloc->free_async_space;
-	spin_unlock(&alloc->lock);
+	mutex_unlock(&alloc->mutex);
 	return free_async_space;
 }