The patch titled
Subject: mm, THP, swap: support PMD swap mapping in swapcache_free_cluster()
has been added to the -mm tree. Its filename is
mm-thp-swap-support-pmd-swap-mapping-in-swapcache_free_cluster.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-swap-support-pmd-swap-mapping-in-swapcache_free_cluster.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-swap-support-pmd-swap-mapping-in-swapcache_free_cluster.patch
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------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: mm, THP, swap: support PMD swap mapping in swapcache_free_cluster()
Previously, during swapout, all PMD page mapping will be split and
replaced with PTE swap mapping. And when clearing the SWAP_HAS_CACHE flag
for the huge swap cluster in swapcache_free_cluster(), the huge swap
cluster will be split. Now, during swapout, the PMD page mapping will be
changed to PMD swap mapping. So when clearing the SWAP_HAS_CACHE flag,
the huge swap cluster will only be split if the PMD swap mapping count is
0. Otherwise, we will keep it as the huge swap cluster. So that we can
swapin a THP as a whole later.
Link: http://lkml.kernel.org/r/20180622035151.6676-5-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/swapfile.c~mm-thp-swap-support-pmd-swap-mapping-in-swapcache_free_cluster mm/swapfile.c
--- a/mm/swapfile.c~mm-thp-swap-support-pmd-swap-mapping-in-swapcache_free_cluster
+++ a/mm/swapfile.c
@@ -514,6 +514,18 @@ static void dec_cluster_info_page(struct
free_cluster(p, idx);
}
+#ifdef CONFIG_THP_SWAP
+static inline int cluster_swapcount(struct swap_cluster_info *ci)
+{
+ if (!ci || !cluster_is_huge(ci))
+ return 0;
+
+ return cluster_count(ci) - SWAPFILE_CLUSTER;
+}
+#else
+#define cluster_swapcount(ci) 0
+#endif
+
/*
* It's possible scan_swap_map() uses a free cluster in the middle of free
* cluster list. Avoiding such abuse to avoid list corruption.
@@ -905,6 +917,7 @@ static void swap_free_cluster(struct swa
struct swap_cluster_info *ci;
ci = lock_cluster(si, offset);
+ memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER);
cluster_set_count_flag(ci, 0, 0);
free_cluster(si, idx);
unlock_cluster(ci);
@@ -1288,24 +1301,30 @@ static void swapcache_free_cluster(swp_e
ci = lock_cluster(si, offset);
VM_BUG_ON(!cluster_is_huge(ci));
+ VM_BUG_ON(!is_cluster_offset(offset));
+ VM_BUG_ON(cluster_count(ci) < SWAPFILE_CLUSTER);
map = si->swap_map + offset;
- for (i = 0; i < SWAPFILE_CLUSTER; i++) {
- val = map[i];
- VM_BUG_ON(!(val & SWAP_HAS_CACHE));
- if (val == SWAP_HAS_CACHE)
- free_entries++;
+ if (!cluster_swapcount(ci)) {
+ for (i = 0; i < SWAPFILE_CLUSTER; i++) {
+ val = map[i];
+ VM_BUG_ON(!(val & SWAP_HAS_CACHE));
+ if (val == SWAP_HAS_CACHE)
+ free_entries++;
+ }
+ if (free_entries != SWAPFILE_CLUSTER)
+ cluster_clear_huge(ci);
}
if (!free_entries) {
- for (i = 0; i < SWAPFILE_CLUSTER; i++)
- map[i] &= ~SWAP_HAS_CACHE;
+ for (i = 0; i < SWAPFILE_CLUSTER; i++) {
+ val = map[i];
+ VM_BUG_ON(!(val & SWAP_HAS_CACHE) ||
+ val == SWAP_HAS_CACHE);
+ map[i] = val & ~SWAP_HAS_CACHE;
+ }
}
- cluster_clear_huge(ci);
unlock_cluster(ci);
if (free_entries == SWAPFILE_CLUSTER) {
spin_lock(&si->lock);
- ci = lock_cluster(si, offset);
- memset(map, 0, SWAPFILE_CLUSTER);
- unlock_cluster(ci);
mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER);
swap_free_cluster(si, idx);
spin_unlock(&si->lock);
_
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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