This is a note to let you know that I've just added the patch titled
Revert "binder_alloc: add missing mmap_lock calls when using the VMA"
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
revert-binder_alloc-add-missing-mmap_lock-calls-when-using-the-vma.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b15655b12ddca7ade09807f790bafb6fab61b50a Mon Sep 17 00:00:00 2001
From: Carlos Llamas <cmllamas@xxxxxxxxxx>
Date: Tue, 2 May 2023 20:12:17 +0000
Subject: Revert "binder_alloc: add missing mmap_lock calls when using the VMA"
From: Carlos Llamas <cmllamas@xxxxxxxxxx>
commit b15655b12ddca7ade09807f790bafb6fab61b50a upstream.
This reverts commit 44e602b4e52f70f04620bbbf4fe46ecb40170bde.
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: 44e602b4e52f ("binder_alloc: add missing mmap_lock calls when using the VMA")
Cc: Liam Howlett <liam.howlett@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230502201220.1756319-1-cmllamas@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/android/binder_alloc.c | 31 ++++++++++---------------------
1 file changed, 10 insertions(+), 21 deletions(-)
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -380,15 +380,12 @@ static struct binder_buffer *binder_allo
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 *));
@@ -916,25 +913,17 @@ void binder_alloc_print_pages(struct seq
* 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);
- for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
- page = &alloc->pages[i];
- if (!page->page_ptr)
- free++;
- else if (list_empty(&page->lru))
- active++;
- else
- lru++;
+ 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)
+ free++;
+ else if (list_empty(&page->lru))
+ active++;
+ 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);
Patches currently in stable-queue which might be from cmllamas@xxxxxxxxxx are
queue-6.3/revert-android-binder-stop-saving-a-pointer-to-the-vma.patch
queue-6.3/binder-fix-uaf-of-alloc-vma-in-race-with-munmap.patch
queue-6.3/binder-fix-uaf-caused-by-faulty-buffer-cleanup.patch
queue-6.3/revert-binder_alloc-add-missing-mmap_lock-calls-when-using-the-vma.patch
queue-6.3/binder-add-lockless-binder_alloc_-set-get-_vma.patch
