Re: [PATCH v4] io: add io_pgtable abstraction

[kernel test robot <lkp@intel.com>]

Hi Alice,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 3e7f562e20ee87a25e104ef4fce557d39d62fa85]

url:    https://github.com/intel-lab-lkp/linux/commits/Alice-Ryhl/io-add-io_pgtable-abstraction/20251219-185557
base:   3e7f562e20ee87a25e104ef4fce557d39d62fa85
patch link:    https://lore.kernel.org/r/20251219-io-pgtable-v4-1-68aaa7a40380%40google.com
patch subject: [PATCH v4] io: add io_pgtable abstraction
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20251221/202512210130.LVNt1EfI-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251221/202512210130.LVNt1EfI-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512210130.LVNt1EfI-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> warning: this function has a `#[must_use]` attribute with no message, but returns a type already marked as `#[must_use]`
   --> rust/kernel/io/pgtable.rs:162:5
   |
   162 | /     pub unsafe fn map_pages(
   163 | |         &self,
   164 | |         iova: usize,
   165 | |         paddr: PhysAddr,
   ...   |
   169 | |         flags: alloc::Flags,
   170 | |     ) -> (usize, Result) {
   | |________________________^
   |
   = help: either add some descriptive message or remove the attribute
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#double_must_use
   = note: `-W clippy::double-must-use` implied by `-W clippy::all`
   = help: to override `-W clippy::all` add `#[allow(clippy::double_must_use)]`

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