[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20241107040239.2847143-9-cmllamas@google.com>
Date: Thu, 7 Nov 2024 04:02:30 +0000
From: Carlos Llamas <cmllamas@...gle.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Arve Hjønnevåg" <arve@...roid.com>, Todd Kjos <tkjos@...roid.com>, Martijn Coenen <maco@...roid.com>,
Joel Fernandes <joel@...lfernandes.org>, Christian Brauner <brauner@...nel.org>,
Carlos Llamas <cmllamas@...gle.com>, Suren Baghdasaryan <surenb@...gle.com>
Cc: linux-kernel@...r.kernel.org, kernel-team@...roid.com,
Nhat Pham <nphamcs@...il.com>, Johannes Weiner <hannes@...xchg.org>,
Barry Song <v-songbaohua@...o.com>, Hillf Danton <hdanton@...a.com>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Subject: [PATCH v2 8/8] binder: use per-vma lock in page installation
Use per-vma locking for concurrent page installations, this minimizes
contention with unrelated vmas improving performance. The mmap_lock is
still acquired when needed though, e.g. before get_user_pages_remote().
Many thanks to Barry Song who posted a similar approach [1].
Link: https://lore.kernel.org/all/20240902225009.34576-1-21cnbao@gmail.com/ [1]
Cc: Nhat Pham <nphamcs@...il.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Barry Song <v-songbaohua@...o.com>
Cc: Suren Baghdasaryan <surenb@...gle.com>
Cc: Hillf Danton <hdanton@...a.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Signed-off-by: Carlos Llamas <cmllamas@...gle.com>
---
drivers/android/binder_alloc.c | 85 +++++++++++++++++++++++-----------
1 file changed, 57 insertions(+), 28 deletions(-)
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 814435a2601a..debfa541e01b 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -233,6 +233,56 @@ static inline bool binder_alloc_is_mapped(struct binder_alloc *alloc)
return smp_load_acquire(&alloc->mapped);
}
+static struct page *binder_page_lookup(struct mm_struct *mm,
+ unsigned long addr)
+{
+ struct page *page;
+ long ret;
+
+ if (!mmget_not_zero(mm))
+ return NULL;
+
+ mmap_read_lock(mm);
+ ret = get_user_pages_remote(mm, addr, 1, 0, &page, NULL);
+ mmap_read_unlock(mm);
+ mmput_async(mm);
+
+ return ret > 0 ? page : NULL;
+}
+
+static int binder_page_insert(struct binder_alloc *alloc,
+ unsigned long addr,
+ struct page *page)
+{
+ struct mm_struct *mm = alloc->mm;
+ struct vm_area_struct *vma;
+ int ret = -ESRCH;
+
+ if (!mmget_not_zero(mm))
+ return -ESRCH;
+
+ /* attempt per-vma lock first */
+ vma = lock_vma_under_rcu(mm, addr);
+ if (!vma)
+ goto lock_mmap;
+
+ if (binder_alloc_is_mapped(alloc))
+ ret = vm_insert_page(vma, addr, page);
+ vma_end_read(vma);
+ goto done;
+
+lock_mmap:
+ /* fall back to mmap_lock */
+ mmap_read_lock(mm);
+ vma = vma_lookup(mm, addr);
+ if (vma && binder_alloc_is_mapped(alloc))
+ ret = vm_insert_page(vma, addr, page);
+ mmap_read_unlock(mm);
+done:
+ mmput_async(mm);
+ return ret;
+}
+
static struct page *binder_page_alloc(struct binder_alloc *alloc,
unsigned long index,
unsigned long addr)
@@ -254,31 +304,14 @@ static int binder_install_single_page(struct binder_alloc *alloc,
unsigned long index,
unsigned long addr)
{
- struct vm_area_struct *vma;
struct page *page;
- long npages;
int ret;
- if (!mmget_not_zero(alloc->mm))
- return -ESRCH;
-
page = binder_page_alloc(alloc, index, addr);
- if (!page) {
- ret = -ENOMEM;
- goto out;
- }
-
- mmap_read_lock(alloc->mm);
- vma = vma_lookup(alloc->mm, addr);
- if (!vma || !binder_alloc_is_mapped(alloc)) {
- mmap_read_unlock(alloc->mm);
- __free_page(page);
- pr_err("%d: %s failed, no vma\n", alloc->pid, __func__);
- ret = -ESRCH;
- goto out;
- }
+ if (!page)
+ return -ENOMEM;
- ret = vm_insert_page(vma, addr, page);
+ ret = binder_page_insert(alloc, addr, page);
switch (ret) {
case -EBUSY:
/*
@@ -288,12 +321,11 @@ static int binder_install_single_page(struct binder_alloc *alloc,
*/
ret = 0;
__free_page(page);
- npages = get_user_pages_remote(alloc->mm, addr, 1, 0, &page, NULL);
- if (npages <= 0) {
+ page = binder_page_lookup(alloc->mm, addr);
+ if (!page) {
pr_err("%d: failed to find page at offset %lx\n",
alloc->pid, addr - alloc->vm_start);
- ret = -ESRCH;
- break;
+ return -ESRCH;
}
fallthrough;
case 0:
@@ -304,12 +336,9 @@ static int binder_install_single_page(struct binder_alloc *alloc,
__free_page(page);
pr_err("%d: %s failed to insert page at offset %lx with %d\n",
alloc->pid, __func__, addr - alloc->vm_start, ret);
- ret = -ENOMEM;
break;
}
- mmap_read_unlock(alloc->mm);
-out:
- mmput_async(alloc->mm);
+
return ret;
}
--
2.47.0.199.ga7371fff76-goog
Powered by blists - more mailing lists