Subject: Re: [PATCH v12 08/31] mm: introduce INIT_VMA()

From: Jerome Glisse <[email-masked]>
Date: Thu, 18 Apr 2019 18:22:13 -0400

On Tue, Apr 16, 2019 at 03:44:59PM +0200, Laurent Dufour wrote:
> Some VMA struct fields need to be initialized once the VMA structure is
> allocated.
> Currently this only concerns anon_vma_chain field but some other will be
> added to support the speculative page fault.
> 
> Instead of spreading the initialization calls all over the code, let's
> introduce a dedicated inline function.
> 
> Signed-off-by: Laurent Dufour <[email-masked]>
> ---
>  fs/exec.c          | 1 +
>  include/linux/mm.h | 5 +++++
>  kernel/fork.c      | 2 +-
>  mm/mmap.c          | 3 +++
>  mm/nommu.c         | 1 +
>  5 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/exec.c b/fs/exec.c
> index 2e0033348d8e..9762e060295c 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -266,6 +266,7 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
>  	vma->vm_start = vma->vm_end - PAGE_SIZE;
>  	vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
>  	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> +	INIT_VMA(vma);
>  
>  	err = insert_vm_struct(mm, vma);
>  	if (err)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 4ba2f53f9d60..2ceb1d2869a6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1407,6 +1407,11 @@ struct zap_details {
>  	pgoff_t last_index;			/* Highest page->index to unmap */
>  };
>  
> +static inline void INIT_VMA(struct vm_area_struct *vma)

Can we leave capital names for macro ? Also i prefer vma_init_struct() (the
one thing i like in C++ is namespace and thus i like namespace_action() for
function name).

Also why not doing a coccinelle patch for this:

@@
struct vm_area_struct *vma;
@@
-INIT_LIST_HEAD(&vma->anon_vma_chain);
+vma_init_struct(vma);

Untested ...

> +{
> +	INIT_LIST_HEAD(&vma->anon_vma_chain);
> +}
> +
>  struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
>  			     pte_t pte, bool with_public_device);
>  #define vm_normal_page(vma, addr, pte) _vm_normal_page(vma, addr, pte, false)
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 915be4918a2b..f8dae021c2e5 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -341,7 +341,7 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
>  
>  	if (new) {
>  		*new = *orig;
> -		INIT_LIST_HEAD(&new->anon_vma_chain);
> +		INIT_VMA(new);
>  	}
>  	return new;
>  }
> diff --git a/mm/mmap.c b/mm/mmap.c
> index bd7b9f293b39..5ad3a3228d76 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1765,6 +1765,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>  	vma->vm_flags = vm_flags;
>  	vma->vm_page_prot = vm_get_page_prot(vm_flags);
>  	vma->vm_pgoff = pgoff;
> +	INIT_VMA(vma);
>  
>  	if (file) {
>  		if (vm_flags & VM_DENYWRITE) {
> @@ -3037,6 +3038,7 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
>  	}
>  
>  	vma_set_anonymous(vma);
> +	INIT_VMA(vma);
>  	vma->vm_start = addr;
>  	vma->vm_end = addr + len;
>  	vma->vm_pgoff = pgoff;
> @@ -3395,6 +3397,7 @@ static struct vm_area_struct *__install_special_mapping(
>  	if (unlikely(vma == NULL))
>  		return ERR_PTR(-ENOMEM);
>  
> +	INIT_VMA(vma);
>  	vma->vm_start = addr;
>  	vma->vm_end = addr + len;
>  
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 749276beb109..acf7ca72ca90 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -1210,6 +1210,7 @@ unsigned long do_mmap(struct file *file,
>  	region->vm_flags = vm_flags;
>  	region->vm_pgoff = pgoff;
>  
> +	INIT_VMA(vma);
>  	vma->vm_flags = vm_flags;
>  	vma->vm_pgoff = pgoff;
>  
> -- 
> 2.21.0
>