The patch titled
Subject: mm, THP: avoid to split THP when reclaim MADV_FREE THP
has been added to the -mm tree. Its filename is
mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp.patch
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The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: mm, THP: avoid to split THP when reclaim MADV_FREE THP
Previously, to reclaim MADV_FREE THP, the THP will be split firstly, then
reclaim each sub-pages. This wastes cycles to split THP and unmap and
free each sub-pages, and split THP even if it has been written since
MADV_FREE. We have to do this because MADV_FREE THP reclaiming shares
same try_to_unmap() calling with swap, while swap needs to split the PMD
page mapping at that time. Now swap can process PMD mapping, this makes
it easy to avoid to split THP when MADV_FREE THP is reclaimed.
Link: http://lkml.kernel.org/r/20180622035151.6676-22-ying.huang@xxxxxxxxx
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
Cc: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN mm/huge_memory.c~mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp mm/huge_memory.c
--- a/mm/huge_memory.c~mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp
+++ a/mm/huge_memory.c
@@ -1672,6 +1672,15 @@ out:
return 0;
}
+static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
+{
+ pgtable_t pgtable;
+
+ pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+ pte_free(mm, pgtable);
+ mm_dec_nr_ptes(mm);
+}
+
#ifdef CONFIG_THP_SWAP
void __split_huge_swap_pmd(struct vm_area_struct *vma,
unsigned long haddr,
@@ -1886,6 +1895,28 @@ bool set_pmd_swap_entry(struct page_vma_
pmd_t swp_pmd;
swp_entry_t entry = { .val = page_private(page) };
+ if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
+ WARN_ON_ONCE(1);
+ return false;
+ }
+
+ /* MADV_FREE page check */
+ if (!PageSwapBacked(page)) {
+ if (!PageDirty(page)) {
+ zap_deposited_table(mm, pvmw->pmd);
+ add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+ goto out_remove_rmap;
+ }
+
+ /*
+ * If the page was redirtied, it cannot be
+ * discarded. Remap the page to page table.
+ */
+ set_pmd_at(mm, address, pvmw->pmd, pmdval);
+ SetPageSwapBacked(page);
+ return false;
+ }
+
if (swap_duplicate(&entry, true) < 0) {
set_pmd_at(mm, address, pvmw->pmd, pmdval);
return false;
@@ -1903,21 +1934,13 @@ bool set_pmd_swap_entry(struct page_vma_
swp_pmd = pmd_swp_mksoft_dirty(swp_pmd);
set_pmd_at(mm, address, pvmw->pmd, swp_pmd);
+out_remove_rmap:
page_remove_rmap(page, true);
put_page(page);
return true;
}
#endif
-static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
-{
- pgtable_t pgtable;
-
- pgtable = pgtable_trans_huge_withdraw(mm, pmd);
- pte_free(mm, pgtable);
- mm_dec_nr_ptes(mm);
-}
-
/*
* Return true if we do MADV_FREE successfully on entire pmd page.
* Otherwise, return false.
diff -puN mm/vmscan.c~mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp mm/vmscan.c
--- a/mm/vmscan.c~mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp
+++ a/mm/vmscan.c
@@ -1137,7 +1137,8 @@ static unsigned long shrink_page_list(st
/* Adding to swap updated mapping */
mapping = page_mapping(page);
}
- } else if (unlikely(PageTransHuge(page))) {
+ } else if (unlikely(PageTransHuge(page)) &&
+ (!thp_swap_supported() || !PageAnon(page))) {
/* Split file THP */
if (split_huge_page_to_list(page, page_list))
goto keep_locked;
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
mm-clear_huge_page-move-order-algorithm-into-a-separate-function.patch
mm-huge-page-copy-target-sub-page-last-when-copy-huge-page.patch
mm-hugetlbfs-rename-address-to-haddr-in-hugetlb_cow.patch
mm-hugetlbfs-pass-fault-address-to-cow-handler.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations-v6.patch
mm-fix-race-between-swapoff-and-mincore.patch
mm-thp-swap-enable-pmd-swap-operations-for-config_thp_swap.patch
mm-thp-swap-make-config_thp_swap-depends-on-config_swap.patch
mm-thp-swap-support-pmd-swap-mapping-in-swap_duplicate.patch
mm-thp-swap-support-pmd-swap-mapping-in-swapcache_free_cluster.patch
mm-thp-swap-support-pmd-swap-mapping-in-free_swap_and_cache-swap_free.patch
mm-thp-swap-support-pmd-swap-mapping-when-splitting-huge-pmd.patch
mm-thp-swap-support-pmd-swap-mapping-in-split_swap_cluster.patch
mm-thp-swap-support-to-read-a-huge-swap-cluster-for-swapin-a-thp.patch
mm-thp-swap-swapin-a-thp-as-a-whole.patch
mm-thp-swap-support-to-count-thp-swapin-and-its-fallback.patch
mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin.patch
mm-thp-swap-support-pmd-swap-mapping-in-swapoff.patch
mm-thp-swap-support-pmd-swap-mapping-in-madvise_free.patch
mm-cgroup-thp-swap-support-to-move-swap-account-for-pmd-swap-mapping.patch
mm-thp-swap-support-to-copy-pmd-swap-mapping-when-fork.patch
mm-thp-swap-free-pmd-swap-mapping-when-zap_huge_pmd.patch
mm-thp-swap-support-pmd-swap-mapping-for-madv_willneed.patch
mm-thp-swap-support-pmd-swap-mapping-in-mincore.patch
mm-thp-swap-support-pmd-swap-mapping-in-common-path.patch
mm-thp-swap-create-pmd-swap-mapping-when-unmap-the-thp.patch
mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp.patch
--
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