[PATCH v2 0/8] binder: faster page installations

[Carlos Llamas <cmllamas@google.com>]

The main focus of these patches is to improve the performance of binder
page installations, primarily by reducing contention on the mmap_lock.
The idea is to allow concurrent page insertion by leveraging per-vma
locking and get_user_pages_remote().

Unfortunately, this required reverting the alloc->lock spinlock back
into a mutex in order to serialize with the shrinker. At least until
finding a better solution e.g. support page zapping with a spinlock.
The trade off is still quite worth it though.

Other patches are also included that remove unsafe and redundant things
such as the alloc->vma pointer or the struct binder_lru_page concept.

Note: I'll work on setting up a page fault handler for binder next.
I believe an idea from Alice Ryhl to deferred the page insertions will
make this finally feasible. I only need to figure out a few performance
bits but if/when done most of the manual page insertion code in binder
could be dropped. :)

Changelog:

v2:
 * fix locking order when upgrading from vma lock to mmap lock
 * switch folio_walk_start() for get_user_pages_remote()
 * release vma/mmap locks and mmput() right after vm_insert_page()
 * add binder_page_alloc() helper for binder_install_single_page()

v1:
https://lore.kernel.org/all/20241105200258.2380168-1-cmllamas@google.com/

Cc: Alice Ryhl <aliceryhl@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Viktor Martensson <vmartensson@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Carlos Llamas (8):
  Revert "binder: switch alloc->mutex to spinlock_t"
  binder: concurrent page installation
  binder: select correct nid for pages in LRU
  binder: remove struct binder_lru_page
  binder: use alloc->mapped to save the vma state
  binder: remove cached alloc->vma pointer
  binder: rename alloc->buffer to vm_start
  binder: use per-vma lock in page installation

 drivers/android/binder.c                |   2 +-
 drivers/android/binder_alloc.c          | 322 ++++++++++++++----------
 drivers/android/binder_alloc.h          |  35 +--
 drivers/android/binder_alloc_selftest.c |  18 +-
 drivers/android/binder_trace.h          |   2 +-
 5 files changed, 212 insertions(+), 167 deletions(-)

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