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SubjectRe: [RFC/PATCH 3/5] mm: get_user_pages: use NON-MOVABLE pages when FOLL_DURABLE flag is set
2013/03/05 15:57, Marek Szyprowski wrote:
> Ensure that newly allocated pages, which are faulted in in FOLL_DURABLE
> mode comes from non-movalbe pageblocks, to workaround migration failures
> with Contiguous Memory Allocator.

In your idea, all users who uses non-movable pageblocks need to set
gup_flags. It's not good.

So how about prepare "get_user_pages_non_movable"? The idea is based on
following Lin Feng's idea:
https://lkml.org/lkml/2013/2/21/123

int get_user_pages_non_movable()
{
int flags = FOLL_TOUCH | FOLL_DURABLE;

if (pages)
flags |= FOLL_GET;
if (write)
flags |= FOLL_WRITE;
if (force)
flags |= FOLL_FORCE;

return __get_user_pages();
}

>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
> include/linux/highmem.h | 12 ++++++++++--
> include/linux/mm.h | 2 ++
> mm/memory.c | 24 ++++++++++++++++++------
> 3 files changed, 30 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index 7fb31da..cf0b9d8 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -168,7 +168,8 @@ __alloc_zeroed_user_highpage(gfp_t movableflags,
> #endif
>
> /**
> - * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
> + * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for
> + * a VMA that the caller knows can move
> * @vma: The VMA the page is to be allocated for
> * @vaddr: The virtual address the page will be inserted into
> *
> @@ -177,11 +178,18 @@ __alloc_zeroed_user_highpage(gfp_t movableflags,
> */
> static inline struct page *
> alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
> - unsigned long vaddr)
> + unsigned long vaddr)
> {
> return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
> }
>
> +static inline struct page *
> +alloc_zeroed_user_highpage(gfp_t gfp, struct vm_area_struct *vma,
> + unsigned long vaddr)
> +{
> + return __alloc_zeroed_user_highpage(gfp, vma, vaddr);
> +}
> +
> static inline void clear_highpage(struct page *page)
> {
> void *kaddr = kmap_atomic(page);
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 9806e54..c11f58f 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -165,6 +165,7 @@ extern pgprot_t protection_map[16];
> #define FAULT_FLAG_RETRY_NOWAIT 0x10 /* Don't drop mmap_sem and wait when retrying */
> #define FAULT_FLAG_KILLABLE 0x20 /* The fault task is in SIGKILL killable region */
> #define FAULT_FLAG_TRIED 0x40 /* second try */

> +#define FAULT_FLAG_NO_CMA 0x80 /* don't use CMA pages */

How about FAULT_FLAG_NO_MIGLATABLE? I want to use it to not only CMA but
also memory hotplug.

>
> /*
> * vm_fault is filled by the the pagefault handler and passed to the vma's
> @@ -1633,6 +1634,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
> #define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */
> #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */
> #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
> +#define FOLL_DURABLE 0x800 /* get the page reference for a long time */
>
> typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
> void *data);
> diff --git a/mm/memory.c b/mm/memory.c
> index 42dfd8e..2b9c2dd 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1816,6 +1816,9 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> int ret;
> unsigned int fault_flags = 0;
>
> + if (gup_flags & FOLL_DURABLE)
> + fault_flags = FAULT_FLAG_NO_CMA;
> +
> /* For mlock, just skip the stack guard page. */
> if (foll_flags & FOLL_MLOCK) {
> if (stack_guard_page(vma, start))
> @@ -2495,7 +2498,7 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
> */
> static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
> unsigned long address, pte_t *page_table, pmd_t *pmd,
> - spinlock_t *ptl, pte_t orig_pte)
> + spinlock_t *ptl, pte_t orig_pte, unsigned int flags)
> __releases(ptl)
> {
> struct page *old_page, *new_page = NULL;
> @@ -2505,6 +2508,10 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
> struct page *dirty_page = NULL;
> unsigned long mmun_start = 0; /* For mmu_notifiers */
> unsigned long mmun_end = 0; /* For mmu_notifiers */
> + gfp_t gfp = GFP_HIGHUSER_MOVABLE;
> +

> + if (IS_ENABLED(CONFIG_CMA) && (flags & FAULT_FLAG_NO_CMA))
> + gfp &= ~__GFP_MOVABLE;

Pleae remove IS_ENABLED(CONFIG_CMA) check.

>
> old_page = vm_normal_page(vma, address, orig_pte);
> if (!old_page) {
> @@ -2668,11 +2675,11 @@ gotten:
> goto oom;
>
> if (is_zero_pfn(pte_pfn(orig_pte))) {
> - new_page = alloc_zeroed_user_highpage_movable(vma, address);
> + new_page = alloc_zeroed_user_highpage(gfp, vma, address);
> if (!new_page)
> goto oom;
> } else {
> - new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
> + new_page = alloc_page_vma(gfp, vma, address);
> if (!new_page)
> goto oom;
> cow_user_page(new_page, old_page, address, vma);
> @@ -3032,7 +3039,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
> }
>
> if (flags & FAULT_FLAG_WRITE) {
> - ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
> + ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte, flags);
> if (ret & VM_FAULT_ERROR)
> ret &= VM_FAULT_ERROR;
> goto out;
> @@ -3187,6 +3194,11 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
> struct vm_fault vmf;
> int ret;
> int page_mkwrite = 0;
> + gfp_t gfp = GFP_HIGHUSER_MOVABLE;
> +

> + if (IS_ENABLED(CONFIG_CMA) && (flags & FAULT_FLAG_NO_CMA))
> + gfp &= ~__GFP_MOVABLE;

Pleae remove IS_ENABLED(CONFIG_CMA) check.

> +
>
> /*
> * If we do COW later, allocate page befor taking lock_page()
> @@ -3197,7 +3209,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
> if (unlikely(anon_vma_prepare(vma)))
> return VM_FAULT_OOM;
>
> - cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
> + cow_page = alloc_page_vma(gfp, vma, address);
> if (!cow_page)
> return VM_FAULT_OOM;
>
> @@ -3614,7 +3626,7 @@ int handle_pte_fault(struct mm_struct *mm,
> if (flags & FAULT_FLAG_WRITE) {
> if (!pte_write(entry))
> return do_wp_page(mm, vma, address,
> - pte, pmd, ptl, entry);
> + pte, pmd, ptl, entry, flags);
> entry = pte_mkdirty(entry);
> }
> entry = pte_mkyoung(entry);
>




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