Re: [linux-next:master 5141/5361] include/linux/hmm.h:102:22: error: field 'mmu_notifier' has incomplete type

[Balbir Singh <bsingharora@gmail.com>]

On Sat, Feb 02, 2019 at 12:14:13AM +0800, kbuild test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   9fe36dd579c794ae5f1c236293c55fb6847e9654
> commit: a3402cb621c1b3908600d3f364e991a6c5a8c06e [5141/5361] mm/hmm: improve driver API to work and wait over a range
> config: x86_64-randconfig-b0-02012138 (attached as .config)
> compiler: gcc-8 (Debian 8.2.0-14) 8.2.0
> reproduce:
>         git checkout a3402cb621c1b3908600d3f364e991a6c5a8c06e
>         # save the attached .config to linux build tree
>         make ARCH=x86_64 
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from kernel/memremap.c:14:
> >> include/linux/hmm.h:102:22: error: field 'mmu_notifier' has incomplete type
>      struct mmu_notifier mmu_notifier;
>                          ^~~~~~~~~~~~
> 
> vim +/mmu_notifier +102 include/linux/hmm.h
> 
>     81	
>     82	
>     83	/*
>     84	 * struct hmm - HMM per mm struct
>     85	 *
>     86	 * @mm: mm struct this HMM struct is bound to
>     87	 * @lock: lock protecting ranges list
>     88	 * @ranges: list of range being snapshotted
>     89	 * @mirrors: list of mirrors for this mm
>     90	 * @mmu_notifier: mmu notifier to track updates to CPU page table
>     91	 * @mirrors_sem: read/write semaphore protecting the mirrors list
>     92	 * @wq: wait queue for user waiting on a range invalidation
>     93	 * @notifiers: count of active mmu notifiers
>     94	 * @dead: is the mm dead ?
>     95	 */
>     96	struct hmm {
>     97		struct mm_struct	*mm;
>     98		struct kref		kref;
>     99		struct mutex		lock;
>    100		struct list_head	ranges;
>    101		struct list_head	mirrors;
>  > 102		struct mmu_notifier	mmu_notifier;

Only HMM_MIRROR depends on MMU_NOTIFIER, but mmu_notifier in
the hmm struct is not conditionally dependent HMM_MIRROR.
The shared config has HMM_MIRROR disabled

Balbir