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Subject[RFC/PATCH 3/5] mm: get_user_pages: use NON-MOVABLE pages when FOLL_DURABLE flag is set
Date
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.

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 */

/*
* 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;

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;
+

/*
* 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);
--
1.7.9.5


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