Re: [PATCH v12 15/31] mm: introduce __lru_cache_add_active_or_unevictable

[Jerome Glisse]

On Tue, Apr 16, 2019 at 03:45:06PM +0200, Laurent Dufour wrote:
> The speculative page fault handler which is run without holding the
> mmap_sem is calling lru_cache_add_active_or_unevictable() but the vm_flags
> is not guaranteed to remain constant.
> Introducing __lru_cache_add_active_or_unevictable() which has the vma flags
> value parameter instead of the vma pointer.
> 
> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>

Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx>

> ---
>  include/linux/swap.h | 10 ++++++++--
>  mm/memory.c          |  8 ++++----
>  mm/swap.c            |  6 +++---
>  3 files changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 4bfb5c4ac108..d33b94eb3c69 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -343,8 +343,14 @@ extern void deactivate_file_page(struct page *page);
>  extern void mark_page_lazyfree(struct page *page);
>  extern void swap_setup(void);
>  
> -extern void lru_cache_add_active_or_unevictable(struct page *page,
> -						struct vm_area_struct *vma);
> +extern void __lru_cache_add_active_or_unevictable(struct page *page,
> +						unsigned long vma_flags);
> +
> +static inline void lru_cache_add_active_or_unevictable(struct page *page,
> +						struct vm_area_struct *vma)
> +{
> +	return __lru_cache_add_active_or_unevictable(page, vma->vm_flags);
> +}
>  
>  /* linux/mm/vmscan.c */
>  extern unsigned long zone_reclaimable_pages(struct zone *zone);
> diff --git a/mm/memory.c b/mm/memory.c
> index 56802850e72c..85ec5ce5c0a8 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2347,7 +2347,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
>  		ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
>  		page_add_new_anon_rmap(new_page, vma, vmf->address, false);
>  		mem_cgroup_commit_charge(new_page, memcg, false, false);
> -		lru_cache_add_active_or_unevictable(new_page, vma);
> +		__lru_cache_add_active_or_unevictable(new_page, vmf->vma_flags);
>  		/*
>  		 * We call the notify macro here because, when using secondary
>  		 * mmu page tables (such as kvm shadow page tables), we want the
> @@ -2896,7 +2896,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
>  	if (unlikely(page != swapcache && swapcache)) {
>  		page_add_new_anon_rmap(page, vma, vmf->address, false);
>  		mem_cgroup_commit_charge(page, memcg, false, false);
> -		lru_cache_add_active_or_unevictable(page, vma);
> +		__lru_cache_add_active_or_unevictable(page, vmf->vma_flags);
>  	} else {
>  		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
>  		mem_cgroup_commit_charge(page, memcg, true, false);
> @@ -3048,7 +3048,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
>  	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
>  	page_add_new_anon_rmap(page, vma, vmf->address, false);
>  	mem_cgroup_commit_charge(page, memcg, false, false);
> -	lru_cache_add_active_or_unevictable(page, vma);
> +	__lru_cache_add_active_or_unevictable(page, vmf->vma_flags);
>  setpte:
>  	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
>  
> @@ -3327,7 +3327,7 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
>  		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
>  		page_add_new_anon_rmap(page, vma, vmf->address, false);
>  		mem_cgroup_commit_charge(page, memcg, false, false);
> -		lru_cache_add_active_or_unevictable(page, vma);
> +		__lru_cache_add_active_or_unevictable(page, vmf->vma_flags);
>  	} else {
>  		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
>  		page_add_file_rmap(page, false);
> diff --git a/mm/swap.c b/mm/swap.c
> index 3a75722e68a9..a55f0505b563 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -450,12 +450,12 @@ void lru_cache_add(struct page *page)
>   * directly back onto it's zone's unevictable list, it does NOT use a
>   * per cpu pagevec.
>   */
> -void lru_cache_add_active_or_unevictable(struct page *page,
> -					 struct vm_area_struct *vma)
> +void __lru_cache_add_active_or_unevictable(struct page *page,
> +					   unsigned long vma_flags)
>  {
>  	VM_BUG_ON_PAGE(PageLRU(page), page);
>  
> -	if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
> +	if (likely((vma_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
>  		SetPageActive(page);
>  	else if (!TestSetPageMlocked(page)) {
>  		/*
> -- 
> 2.21.0
>