The patch titled
Subject: mm, madvise: introduce MADV_PAGEOUT
has been added to the -mm tree. Its filename is
mm-introduce-madv_pageout.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-introduce-madv_pageout.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-introduce-madv_pageout.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: mm, madvise: introduce MADV_PAGEOUT
When a process expects no accesses to a certain memory range for a long
time, it could hint kernel that the pages can be reclaimed instantly but
data should be preserved for future use. This could reduce workingset
eviction so it ends up increasing performance.
This patch introduces the new MADV_PAGEOUT hint to madvise(2) syscall.
MADV_PAGEOUT can be used by a process to mark a memory range as not
expected to be used for a long time so that kernel reclaims *any LRU*
pages instantly. The hint can help kernel in deciding which pages to
evict proactively.
A note: It doesn't apply SWAP_CLUSTER_MAX LRU page isolation limit
intentionally because it's automatically bounded by PMD size. If PMD
size(e.g., 256) makes some trouble, we could fix it later by limit it to
SWAP_CLUSTER_MAX[1].
- man-page material
MADV_PAGEOUT (since Linux x.x)
Do not expect access in the near future so pages in the specified regions
could be reclaimed instantly regardless of memory pressure. Thus, access
in the range after successful operation could cause major page fault but
never lose the up-to-date contents unlike MADV_DONTNEED. Pages belonging
to a shared mapping are only processed if a write access is allowed for
the calling process.
MADV_PAGEOUT cannot be applied to locked pages, Huge TLB pages, or
VM_PFNMAP pages.
[1] https://lore.kernel.org/lkml/20190710194719.GS29695@xxxxxxxxxxxxxx/
Link: http://lkml.kernel.org/r/20190723062539.198697-5-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Daniel Colascione <dancol@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Oleksandr Natalenko <oleksandr@xxxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Sonny Rao <sonnyrao@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Tim Murray <timmurray@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/swap.h | 1
include/uapi/asm-generic/mman-common.h | 1
mm/madvise.c | 195 +++++++++++++++++++++++
mm/vmscan.c | 55 ++++++
4 files changed, 252 insertions(+)
--- a/include/linux/swap.h~mm-introduce-madv_pageout
+++ a/include/linux/swap.h
@@ -365,6 +365,7 @@ extern int vm_swappiness;
extern int remove_mapping(struct address_space *mapping, struct page *page);
extern unsigned long vm_total_pages;
+extern unsigned long reclaim_pages(struct list_head *page_list);
#ifdef CONFIG_NUMA
extern int node_reclaim_mode;
extern int sysctl_min_unmapped_ratio;
--- a/include/uapi/asm-generic/mman-common.h~mm-introduce-madv_pageout
+++ a/include/uapi/asm-generic/mman-common.h
@@ -46,6 +46,7 @@
#define MADV_WILLNEED 3 /* will need these pages */
#define MADV_DONTNEED 4 /* don't need these pages */
#define MADV_COLD 5 /* deactivate these pages */
+#define MADV_PAGEOUT 6 /* reclaim these pages */
/* common parameters: try to keep these consistent across architectures */
#define MADV_FREE 8 /* free pages only if memory pressure */
--- a/mm/madvise.c~mm-introduce-madv_pageout
+++ a/mm/madvise.c
@@ -11,6 +11,7 @@
#include <linux/syscalls.h>
#include <linux/mempolicy.h>
#include <linux/page-isolation.h>
+#include <linux/page_idle.h>
#include <linux/userfaultfd_k.h>
#include <linux/hugetlb.h>
#include <linux/falloc.h>
@@ -41,6 +42,7 @@ static int madvise_need_mmap_write(int b
case MADV_WILLNEED:
case MADV_DONTNEED:
case MADV_COLD:
+ case MADV_PAGEOUT:
case MADV_FREE:
return 0;
default:
@@ -480,6 +482,196 @@ static long madvise_cold(struct vm_area_
return 0;
}
+static int madvise_pageout_pte_range(pmd_t *pmd, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
+{
+ struct mmu_gather *tlb = walk->private;
+ struct mm_struct *mm = tlb->mm;
+ struct vm_area_struct *vma = walk->vma;
+ pte_t *orig_pte, *pte, ptent;
+ spinlock_t *ptl;
+ LIST_HEAD(page_list);
+ struct page *page;
+ unsigned long next;
+
+ if (fatal_signal_pending(current))
+ return -EINTR;
+
+ next = pmd_addr_end(addr, end);
+ if (pmd_trans_huge(*pmd)) {
+ pmd_t orig_pmd;
+
+ tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
+ ptl = pmd_trans_huge_lock(pmd, vma);
+ if (!ptl)
+ return 0;
+
+ orig_pmd = *pmd;
+ if (is_huge_zero_pmd(orig_pmd))
+ goto huge_unlock;
+
+ if (unlikely(!pmd_present(orig_pmd))) {
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(orig_pmd));
+ goto huge_unlock;
+ }
+
+ page = pmd_page(orig_pmd);
+ if (next - addr != HPAGE_PMD_SIZE) {
+ int err;
+
+ if (page_mapcount(page) != 1)
+ goto huge_unlock;
+ get_page(page);
+ spin_unlock(ptl);
+ lock_page(page);
+ err = split_huge_page(page);
+ unlock_page(page);
+ put_page(page);
+ if (!err)
+ goto regular_page;
+ return 0;
+ }
+
+ if (pmd_young(orig_pmd)) {
+ pmdp_invalidate(vma, addr, pmd);
+ orig_pmd = pmd_mkold(orig_pmd);
+
+ set_pmd_at(mm, addr, pmd, orig_pmd);
+ tlb_remove_tlb_entry(tlb, pmd, addr);
+ }
+
+ ClearPageReferenced(page);
+ test_and_clear_page_young(page);
+
+ if (!isolate_lru_page(page))
+ list_add(&page->lru, &page_list);
+huge_unlock:
+ spin_unlock(ptl);
+ reclaim_pages(&page_list);
+ return 0;
+ }
+
+ if (pmd_trans_unstable(pmd))
+ return 0;
+regular_page:
+ tlb_change_page_size(tlb, PAGE_SIZE);
+ orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+ flush_tlb_batched_pending(mm);
+ arch_enter_lazy_mmu_mode();
+ for (; addr < end; pte++, addr += PAGE_SIZE) {
+ ptent = *pte;
+ if (!pte_present(ptent))
+ continue;
+
+ page = vm_normal_page(vma, addr, ptent);
+ if (!page)
+ continue;
+
+ /*
+ * creating a THP page is expensive so split it only if we
+ * are sure it's worth. Split it if we are only owner.
+ */
+ if (PageTransCompound(page)) {
+ if (page_mapcount(page) != 1)
+ break;
+ get_page(page);
+ if (!trylock_page(page)) {
+ put_page(page);
+ break;
+ }
+ pte_unmap_unlock(orig_pte, ptl);
+ if (split_huge_page(page)) {
+ unlock_page(page);
+ put_page(page);
+ pte_offset_map_lock(mm, pmd, addr, &ptl);
+ break;
+ }
+ unlock_page(page);
+ put_page(page);
+ pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ pte--;
+ addr -= PAGE_SIZE;
+ continue;
+ }
+
+ VM_BUG_ON_PAGE(PageTransCompound(page), page);
+
+ if (pte_young(ptent)) {
+ ptent = ptep_get_and_clear_full(mm, addr, pte,
+ tlb->fullmm);
+ ptent = pte_mkold(ptent);
+ set_pte_at(mm, addr, pte, ptent);
+ tlb_remove_tlb_entry(tlb, pte, addr);
+ }
+ ClearPageReferenced(page);
+ test_and_clear_page_young(page);
+
+ if (!isolate_lru_page(page))
+ list_add(&page->lru, &page_list);
+ }
+
+ arch_leave_lazy_mmu_mode();
+ pte_unmap_unlock(orig_pte, ptl);
+ reclaim_pages(&page_list);
+ cond_resched();
+
+ return 0;
+}
+
+static void madvise_pageout_page_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end)
+{
+ struct mm_walk pageout_walk = {
+ .pmd_entry = madvise_pageout_pte_range,
+ .mm = vma->vm_mm,
+ .private = tlb,
+ };
+
+ tlb_start_vma(tlb, vma);
+ walk_page_range(addr, end, &pageout_walk);
+ tlb_end_vma(tlb, vma);
+}
+
+static inline bool can_do_pageout(struct vm_area_struct *vma)
+{
+ if (vma_is_anonymous(vma))
+ return true;
+ if (!vma->vm_file)
+ return false;
+ /*
+ * paging out pagecache only for non-anonymous mappings that correspond
+ * to the files the calling process could (if tried) open for writing;
+ * otherwise we'd be including shared non-exclusive mappings, which
+ * opens a side channel.
+ */
+ return inode_owner_or_capable(file_inode(vma->vm_file)) ||
+ inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
+}
+
+static long madvise_pageout(struct vm_area_struct *vma,
+ struct vm_area_struct **prev,
+ unsigned long start_addr, unsigned long end_addr)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct mmu_gather tlb;
+
+ *prev = vma;
+ if (!can_madv_lru_vma(vma))
+ return -EINVAL;
+
+ if (!can_do_pageout(vma))
+ return 0;
+
+ lru_add_drain();
+ tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
+ madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
+ tlb_finish_mmu(&tlb, start_addr, end_addr);
+
+ return 0;
+}
+
static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
@@ -870,6 +1062,8 @@ madvise_vma(struct vm_area_struct *vma,
return madvise_willneed(vma, prev, start, end);
case MADV_COLD:
return madvise_cold(vma, prev, start, end);
+ case MADV_PAGEOUT:
+ return madvise_pageout(vma, prev, start, end);
case MADV_FREE:
case MADV_DONTNEED:
return madvise_dontneed_free(vma, prev, start, end, behavior);
@@ -892,6 +1086,7 @@ madvise_behavior_valid(int behavior)
case MADV_DONTNEED:
case MADV_FREE:
case MADV_COLD:
+ case MADV_PAGEOUT:
#ifdef CONFIG_KSM
case MADV_MERGEABLE:
case MADV_UNMERGEABLE:
--- a/mm/vmscan.c~mm-introduce-madv_pageout
+++ a/mm/vmscan.c
@@ -2158,6 +2158,61 @@ static void shrink_active_list(unsigned
nr_deactivate, nr_rotated, sc->priority, file);
}
+unsigned long reclaim_pages(struct list_head *page_list)
+{
+ int nid = -1;
+ unsigned long nr_reclaimed = 0;
+ LIST_HEAD(node_page_list);
+ struct reclaim_stat dummy_stat;
+ struct page *page;
+ struct scan_control sc = {
+ .gfp_mask = GFP_KERNEL,
+ .priority = DEF_PRIORITY,
+ .may_writepage = 1,
+ .may_unmap = 1,
+ .may_swap = 1,
+ };
+
+ while (!list_empty(page_list)) {
+ page = lru_to_page(page_list);
+ if (nid == -1) {
+ nid = page_to_nid(page);
+ INIT_LIST_HEAD(&node_page_list);
+ }
+
+ if (nid == page_to_nid(page)) {
+ list_move(&page->lru, &node_page_list);
+ continue;
+ }
+
+ nr_reclaimed += shrink_page_list(&node_page_list,
+ NODE_DATA(nid),
+ &sc, 0,
+ &dummy_stat, false);
+ while (!list_empty(&node_page_list)) {
+ page = lru_to_page(&node_page_list);
+ list_del(&page->lru);
+ putback_lru_page(page);
+ }
+
+ nid = -1;
+ }
+
+ if (!list_empty(&node_page_list)) {
+ nr_reclaimed += shrink_page_list(&node_page_list,
+ NODE_DATA(nid),
+ &sc, 0,
+ &dummy_stat, false);
+ while (!list_empty(&node_page_list)) {
+ page = lru_to_page(&node_page_list);
+ list_del(&page->lru);
+ putback_lru_page(page);
+ }
+ }
+
+ return nr_reclaimed;
+}
+
/*
* The inactive anon list should be small enough that the VM never has
* to do too much work.
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
mm-introduce-madv_cold.patch
mm-change-pageref_reclaim_clean-with-page_refreclaim.patch
mm-account-nr_isolated_xxx-in-_lru_page.patch
mm-introduce-madv_pageout.patch
mm-factor-out-common-parts-between-madv_cold-and-madv_pageout.patch
