Re: [PATCH v2 1/1] Make Guard::lock_ref unavailable if Lock is not Sync

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

Hi Priya,

kernel test robot noticed the following build errors:

[auto build test ERROR on tip/locking/core]
[also build test ERROR on rust/rust-next linus/master v7.2-rc7 next-20260814]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Priya-Bala-Govindasamy/Make-Guard-lock_ref-unavailable-if-Lock-is-not-Sync/20260814-173656
base:   tip/locking/core
patch link:    https://lore.kernel.org/r/878cfb22ab185874bc363e2b7910a6978af646ab.1782763889.git.pgovind2%40uci.edu
patch subject: [PATCH v2 1/1] Make Guard::lock_ref unavailable if Lock is not Sync
config: arm64-randconfig-003-20260817 (https://download.01.org/0day-ci/archive/20260817/202608172043.JxF675RT-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
rustc: rustc 1.96.0 (ac68faa20 2026-05-25)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260817/202608172043.JxF675RT-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/202608172043.JxF675RT-lkp@intel.com/

All errors (new ones prefixed by >>):

>> error[E0277]: `T` cannot be sent between threads safely
   --> rust/doctests_kernel_generated.rs:20824:33
   |
   20824 |     assert!(core::ptr::eq(guard.lock_ref(), lock));
   |                                 ^^^^^^^^ `T` cannot be sent between threads safely
   |
   = note: required for `Lock<T, B>` to implement `Sync`
   note: required by a bound in `rust_doctest_kernel_alloc_allocator_rs_0::kernel::sync::lock::Guard::<'a, T, B>::lock_ref`
   --> rust/kernel/sync/lock.rs:239:21
   |
   237 |     pub fn lock_ref(&self) -> &'a Lock<T, B>
   |            -------- required by a bound in this associated function
   238 |     where
   239 |         Lock<T, B>: Sync,
   |                     ^^^^ required by this bound in `Guard::<'a, T, B>::lock_ref`
   help: consider restricting type parameter `T` with trait `Send`
   |
   20822 | fn assert_held<T: core::marker::Send, B: Backend>(guard: &Guard<'_, T, B>, lock: &Lock<T, B>) {
   |                 ++++++++++++++++++++

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