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Subject[PATCH v3 3/3] Prevent activation of page in madvise_dontneed
Date
Now zap_pte_range alwayas activates pages which are pte_young &&
!VM_SequentialReadHint(vma). But in case of calling MADV_DONTNEED,
it's unnecessary since the page wouldn't use any more.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Wu Fengguang <fengguang.wu@intel.com>

Changelog since v2:
- remove unnecessary description
Changelog since v1:
- change word from promote to activate
- add activate argument to zap_pte_range and family function

---
include/linux/mm.h | 4 ++--
mm/madvise.c | 4 ++--
mm/memory.c | 38 +++++++++++++++++++++++---------------
mm/mmap.c | 4 ++--
4 files changed, 29 insertions(+), 21 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e097df6..6032881 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -779,11 +779,11 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
unsigned long size);
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
- unsigned long size, struct zap_details *);
+ unsigned long size, struct zap_details *, bool activate);
unsigned long unmap_vmas(struct mmu_gather **tlb,
struct vm_area_struct *start_vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
- struct zap_details *);
+ struct zap_details *, bool activate);

/**
* mm_walk - callbacks for walk_page_range
diff --git a/mm/madvise.c b/mm/madvise.c
index 319528b..8bc4b2d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -171,9 +171,9 @@ static long madvise_dontneed(struct vm_area_struct * vma,
.nonlinear_vma = vma,
.last_index = ULONG_MAX,
};
- zap_page_range(vma, start, end - start, &details);
+ zap_page_range(vma, start, end - start, &details, false);
} else
- zap_page_range(vma, start, end - start, NULL);
+ zap_page_range(vma, start, end - start, NULL, false);
return 0;
}

diff --git a/mm/memory.c b/mm/memory.c
index 2c989f3..b8d38bd 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -891,7 +891,8 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
static unsigned long zap_pte_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
- long *zap_work, struct zap_details *details)
+ long *zap_work, struct zap_details *details,
+ bool activate)
{
struct mm_struct *mm = tlb->mm;
pte_t *pte;
@@ -949,7 +950,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
if (pte_dirty(ptent))
set_page_dirty(page);
if (pte_young(ptent) &&
- likely(!VM_SequentialReadHint(vma)))
+ likely(!VM_SequentialReadHint(vma)) &&
+ activate)
mark_page_accessed(page);
rss[MM_FILEPAGES]--;
}
@@ -989,7 +991,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end,
- long *zap_work, struct zap_details *details)
+ long *zap_work, struct zap_details *details,
+ bool activate)
{
pmd_t *pmd;
unsigned long next;
@@ -1002,7 +1005,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
continue;
}
next = zap_pte_range(tlb, vma, pmd, addr, next,
- zap_work, details);
+ zap_work, details, activate);
} while (pmd++, addr = next, (addr != end && *zap_work > 0));

return addr;
@@ -1011,7 +1014,8 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end,
- long *zap_work, struct zap_details *details)
+ long *zap_work, struct zap_details *details,
+ bool activate)
{
pud_t *pud;
unsigned long next;
@@ -1024,7 +1028,7 @@ static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
continue;
}
next = zap_pmd_range(tlb, vma, pud, addr, next,
- zap_work, details);
+ zap_work, details, activate);
} while (pud++, addr = next, (addr != end && *zap_work > 0));

return addr;
@@ -1033,7 +1037,8 @@ static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
static unsigned long unmap_page_range(struct mmu_gather *tlb,
struct vm_area_struct *vma,
unsigned long addr, unsigned long end,
- long *zap_work, struct zap_details *details)
+ long *zap_work, struct zap_details *details,
+ bool activate)
{
pgd_t *pgd;
unsigned long next;
@@ -1052,7 +1057,7 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
continue;
}
next = zap_pud_range(tlb, vma, pgd, addr, next,
- zap_work, details);
+ zap_work, details, activate);
} while (pgd++, addr = next, (addr != end && *zap_work > 0));
tlb_end_vma(tlb, vma);
mem_cgroup_uncharge_end();
@@ -1075,6 +1080,7 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
* @end_addr: virtual address at which to end unmapping
* @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
* @details: details of nonlinear truncation or shared cache invalidation
+ * @activate: whether pages included in the vma should be activated or not
*
* Returns the end address of the unmapping (restart addr if interrupted).
*
@@ -1096,7 +1102,7 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
unsigned long unmap_vmas(struct mmu_gather **tlbp,
struct vm_area_struct *vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
- struct zap_details *details)
+ struct zap_details *details, bool activate)
{
long zap_work = ZAP_BLOCK_SIZE;
unsigned long tlb_start = 0; /* For tlb_finish_mmu */
@@ -1149,8 +1155,8 @@ unsigned long unmap_vmas(struct mmu_gather **tlbp,

start = end;
} else
- start = unmap_page_range(*tlbp, vma,
- start, end, &zap_work, details);
+ start = unmap_page_range(*tlbp, vma, start,
+ end, &zap_work, details, activate);

if (zap_work > 0) {
BUG_ON(start != end);
@@ -1184,9 +1190,10 @@ out:
* @address: starting address of pages to zap
* @size: number of bytes to zap
* @details: details of nonlinear truncation or shared cache invalidation
+ * @activate: whether pages included in the vma should be activated or not
*/
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
- unsigned long size, struct zap_details *details)
+ unsigned long size, struct zap_details *details, bool activate)
{
struct mm_struct *mm = vma->vm_mm;
struct mmu_gather *tlb;
@@ -1196,7 +1203,8 @@ unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
lru_add_drain();
tlb = tlb_gather_mmu(mm, 0);
update_hiwater_rss(mm);
- end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
+ end = unmap_vmas(&tlb, vma, address, end, &nr_accounted,
+ details, activate);
if (tlb)
tlb_finish_mmu(tlb, address, end);
return end;
@@ -1220,7 +1228,7 @@ int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
if (address < vma->vm_start || address + size > vma->vm_end ||
!(vma->vm_flags & VM_PFNMAP))
return -1;
- zap_page_range(vma, address, size, NULL);
+ zap_page_range(vma, address, size, NULL, false);
return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);
@@ -2481,7 +2489,7 @@ again:
}

restart_addr = zap_page_range(vma, start_addr,
- end_addr - start_addr, details);
+ end_addr - start_addr, details, true);
need_break = need_resched() || spin_needbreak(details->i_mmap_lock);

if (restart_addr >= end_addr) {
diff --git a/mm/mmap.c b/mm/mmap.c
index b179abb..0ed5ab3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1904,7 +1904,7 @@ static void unmap_region(struct mm_struct *mm,
lru_add_drain();
tlb = tlb_gather_mmu(mm, 0);
update_hiwater_rss(mm);
- unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
+ unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL, true);
vm_unacct_memory(nr_accounted);
free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
next? next->vm_start: 0);
@@ -2278,7 +2278,7 @@ void exit_mmap(struct mm_struct *mm)
tlb = tlb_gather_mmu(mm, 1);
/* update_hiwater_rss(mm) here? but nobody should be looking */
/* Use -1 here to ensure all VMAs in the mm are unmapped */
- end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
+ end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL, true);
vm_unacct_memory(nr_accounted);

free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
--
1.7.0.4


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