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binder: use per-vma lock in page installation

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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@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20241210143114.661252-8-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Carlos Llamas 2024-12-10 14:31:03 +00:00 • committed by Greg Kroah-Hartman
parent 0a7bf6866d
commit 9e2aa76549
1 changed files with 50 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

67
drivers/android/binder_alloc.c
View file

@ -233,6 +233,53 @@ static inline bool binder_alloc_is_mapped(struct binder_alloc *alloc)
return smp_load_acquire(&alloc->mapped);
}
static struct page *binder_page_lookup(struct binder_alloc *alloc,
unsigned long addr)
{
struct mm_struct *mm = alloc->mm;
struct page *page;
long npages = 0;
/*
* Find an existing page in the remote mm. If missing,
* don't attempt to fault-in just propagate an error.
*/
mmap_read_lock(mm);
if (binder_alloc_is_mapped(alloc))
npages = get_user_pages_remote(mm, addr, 1, FOLL_NOFAULT,
&page, NULL);
mmap_read_unlock(mm);
return npages > 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;
/* attempt per-vma lock first */
vma = lock_vma_under_rcu(mm, addr);
if (vma) {
if (binder_alloc_is_mapped(alloc))
ret = vm_insert_page(vma, addr, page);
vma_end_read(vma);
return ret;
}
/* 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);
return ret;
}
static struct page *binder_page_alloc(struct binder_alloc *alloc,
unsigned long index)
{
@ -268,9 +315,7 @@ 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))
@ -282,16 +327,7 @@ static int binder_install_single_page(struct binder_alloc *alloc,
goto out;
}
mmap_read_lock(alloc->mm);
vma = vma_lookup(alloc->mm, addr);
if (!vma || !binder_alloc_is_mapped(alloc)) {
binder_free_page(page);
pr_err("%d: %s failed, no vma\n", alloc->pid, __func__);
ret = -ESRCH;
goto unlock;
}
ret = vm_insert_page(vma, addr, page);
ret = binder_page_insert(alloc, addr, page);
switch (ret) {
case -EBUSY:
/*
@ -301,9 +337,8 @@ static int binder_install_single_page(struct binder_alloc *alloc,
*/
ret = 0;
binder_free_page(page);
npages = get_user_pages_remote(alloc->mm, addr, 1,
FOLL_NOFAULT, &page, NULL);
if (npages <= 0) {
page = binder_page_lookup(alloc, addr);
if (!page) {
pr_err("%d: failed to find page at offset %lx\n",
alloc->pid, addr - alloc->vm_start);
ret = -ESRCH;
@ -321,8 +356,6 @@ static int binder_install_single_page(struct binder_alloc *alloc,
ret = -ENOMEM;
break;
}
unlock:
mmap_read_unlock(alloc->mm);
out:
mmput_async(alloc->mm);
return ret;