From c0fd2101781ef761b636769b2f445351f71c3626 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Tue, 2 May 2023 20:12:18 +0000 Subject: Revert "android: binder: stop saving a pointer to the VMA" This reverts commit a43cfc87caaf46710c8027a8c23b8a55f1078f19. This patch fixed an issue reported by syzkaller in [1]. However, this turned out to be only a band-aid in binder. The root cause, as bisected by syzkaller, was fixed by commit 5789151e48ac ("mm/mmap: undo ->mmap() when mas_preallocate() fails"). We no longer need the patch for binder. Reverting such patch allows us to have a lockless access to alloc->vma in specific cases where the mmap_lock is not required. This approach avoids the contention that caused a performance regression. [1] https://lore.kernel.org/all/0000000000004a0dbe05e1d749e0@google.com [cmllamas: resolved conflicts with rework of alloc->mm and removal of binder_alloc_set_vma() also fixed comment section] Fixes: a43cfc87caaf ("android: binder: stop saving a pointer to the VMA") Cc: Liam Howlett Cc: Suren Baghdasaryan Cc: stable@vger.kernel.org Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20230502201220.1756319-2-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/android/binder_alloc.h') diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h index 0f811ac4bcff..138d1d5af9ce 100644 --- a/drivers/android/binder_alloc.h +++ b/drivers/android/binder_alloc.h @@ -75,7 +75,7 @@ struct binder_lru_page { /** * struct binder_alloc - per-binder proc state for binder allocator * @mutex: protects binder_alloc fields - * @vma_addr: vm_area_struct->vm_start passed to mmap_handler + * @vma: vm_area_struct passed to mmap_handler * (invariant after mmap) * @mm: copy of task->mm (invariant after open) * @buffer: base of per-proc address space mapped via mmap @@ -99,7 +99,7 @@ struct binder_lru_page { */ struct binder_alloc { struct mutex mutex; - unsigned long vma_addr; + struct vm_area_struct *vma; struct mm_struct *mm; void __user *buffer; struct list_head buffers; -- cgit v1.2.3