Commit b15655b1 authored by Carlos Llamas's avatar Carlos Llamas Committed by Greg Kroah-Hartman
Browse files

Revert "binder_alloc: add missing mmap_lock calls when using the VMA" 



This reverts commit 44e602b4.

This caused a performance regression particularly when pages are getting
reclaimed. We don't need to acquire the mmap_lock to determine when the
binder buffer has been fully initialized. A subsequent patch will bring
back the lockless approach for this.

[cmllamas: resolved trivial conflicts with renaming of alloc->mm]

Fixes: 44e602b4 ("binder_alloc: add missing mmap_lock calls when using the VMA")
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarCarlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20230502201220.1756319-1-cmllamas@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent bdc1c5fa

drivers/android/binder_alloc.c

+10 −21
Original line number Diff line number Diff line
@@ -380,15 +380,12 @@ static struct binder_buffer *binder_alloc_new_buf_locked( 
	size_t size, data_offsets_size;

	int ret;



	mmap_read_lock(alloc->mm);

	if (!binder_alloc_get_vma(alloc)) {

		mmap_read_unlock(alloc->mm);

		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,

				   "%d: binder_alloc_buf, no vma\n",

				   alloc->pid);

		return ERR_PTR(-ESRCH);

	}

	mmap_read_unlock(alloc->mm);



	data_offsets_size = ALIGN(data_size, sizeof(void *)) +

		ALIGN(offsets_size, sizeof(void *));
@@ -916,14 +913,7 @@ void binder_alloc_print_pages(struct seq_file *m, 
	 * Make sure the binder_alloc is fully initialized, otherwise we might

	 * read inconsistent state.

	 */



	mmap_read_lock(alloc->mm);

	if (binder_alloc_get_vma(alloc) == NULL) {

		mmap_read_unlock(alloc->mm);

		goto uninitialized;

	}



	mmap_read_unlock(alloc->mm);

	if (binder_alloc_get_vma(alloc) != NULL) {

		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {

			page = &alloc->pages[i];

			if (!page->page_ptr)
@@ -933,8 +923,7 @@ void binder_alloc_print_pages(struct seq_file *m, 
			else

				lru++;

		}



uninitialized:

	}

	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);