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rust_binder: use lock_vma_under_rcu() in use_page_slow()

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There's no reason to lock the whole mm when we are doing operations on
the vma if we can help it, so to reduce contention, use the
lock_vma_under_rcu() abstraction.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Link: https://patch.msgid.link/20260218-binder-vma-rcu-v1-1-8bd45b2b1183@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alice Ryhl
2026-02-18 15:13:23 +00:00
committed by Greg Kroah-Hartman
parent 2e303f0feb
commit a0b9b0f143
1 changed files with 19 additions and 18 deletions
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37
drivers/android/binder/page_range.rs
View File

@@ -435,24 +435,25 @@ impl ShrinkablePageRange {
//
// Using `mmput_async` avoids this, because then the `mm` cleanup is instead queued to a
// workqueue.
check_vma(
MmWithUser::into_mmput_async(self.mm.mmget_not_zero().ok_or(ESRCH)?)
.mmap_read_lock()
.vma_lookup(vma_addr)
.ok_or(ESRCH)?,
self,
)
.ok_or(ESRCH)?
.vm_insert_page(user_page_addr, &new_page)
.inspect_err(|err| {
pr_warn!(
"Failed to vm_insert_page({}): vma_addr:{} i:{} err:{:?}",
user_page_addr,
vma_addr,
i,
err
)
})?;
let mm = MmWithUser::into_mmput_async(self.mm.mmget_not_zero().ok_or(ESRCH)?);
{
let vma_read;
let mmap_read;
let vma = if let Some(ret) = mm.lock_vma_under_rcu(vma_addr) {
vma_read = ret;
check_vma(&vma_read, self)
} else {
mmap_read = mm.mmap_read_lock();
mmap_read
.vma_lookup(vma_addr)
.and_then(|vma| check_vma(vma, self))
};
match vma {
Some(vma) => vma.vm_insert_page(user_page_addr, &new_page)?,
None => return Err(ESRCH),
}
}
let inner = self.lock.lock();