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Date:   Tue, 13 Apr 2021 23:43:41 -0700 (PDT)
From:   Hugh Dickins <hughd@google.com>
To:     Axel Rasmussen <axelrasmussen@google.com>
cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Joe Perches <joe@perches.com>,
        Lokesh Gidra <lokeshgidra@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Peter Xu <peterx@redhat.com>, Shaohua Li <shli@fb.com>,
        Shuah Khan <shuah@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Wang Qing <wangqing@vivo.com>, linux-api@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
        Brian Geffon <bgeffon@google.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        Mina Almasry <almasrymina@google.com>,
        Oliver Upton <oupton@google.com>
Subject: Re: [PATCH v2 1/9] userfaultfd/hugetlbfs: avoid including userfaultfd_k.h
 in hugetlb.h
In-Reply-To: <20210413051721.2896915-2-axelrasmussen@google.com>
Message-ID: <alpine.LSU.2.11.2104132336001.9086@eggly.anvils>
References: <20210413051721.2896915-1-axelrasmussen@google.com> <20210413051721.2896915-2-axelrasmussen@google.com>
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On Mon, 12 Apr 2021, Axel Rasmussen wrote:

> Minimizing header file inclusion is desirable. In this case, we can do
> so just by forward declaring the enumeration our signature relies upon.
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
> ---
>  include/linux/hugetlb.h | 4 +++-
>  mm/hugetlb.c            | 1 +
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 09f1fd12a6fa..3f47650ab79b 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -11,7 +11,6 @@
>  #include <linux/kref.h>
>  #include <linux/pgtable.h>
>  #include <linux/gfp.h>
> -#include <linux/userfaultfd_k.h>
>  
>  struct ctl_table;
>  struct user_struct;
> @@ -135,6 +134,8 @@ void hugetlb_show_meminfo(void);
>  unsigned long hugetlb_total_pages(void);
>  vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
>  			unsigned long address, unsigned int flags);
> +
> +enum mcopy_atomic_mode;

Wrongly placed: the CONFIG_USERFAULTFD=y CONFIG_HUGETLB_PAGE=n build
fails. Better place it up above with struct ctl_table etc.

>  #ifdef CONFIG_USERFAULTFD
>  int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
>  				struct vm_area_struct *dst_vma,
> @@ -143,6 +144,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
>  				enum mcopy_atomic_mode mode,
>  				struct page **pagep);
>  #endif /* CONFIG_USERFAULTFD */
> +
>  bool hugetlb_reserve_pages(struct inode *inode, long from, long to,
>  						struct vm_area_struct *vma,
>  						vm_flags_t vm_flags);
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 54d81d5947ed..b1652e747318 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -40,6 +40,7 @@
>  #include <linux/hugetlb_cgroup.h>
>  #include <linux/node.h>
>  #include <linux/page_owner.h>
> +#include <linux/userfaultfd_k.h>
>  #include "internal.h"
>  
>  int hugetlb_max_hstate __read_mostly;
> -- 
> 2.31.1.295.g9ea45b61b8-goog
> 
>