The patch titled
Subject: mm, THP, swap: support to copy PMD swap mapping when fork()
has been added to the -mm tree. Its filename is
mm-thp-swap-support-to-copy-pmd-swap-mapping-when-fork.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-swap-support-to-copy-pmd-swap-mapping-when-fork.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-swap-support-to-copy-pmd-swap-mapping-when-fork.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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, swap: support to copy PMD swap mapping when fork()
During fork, the page table need to be copied from parent to child. A PMD
swap mapping need to be copied too and the swap reference count need to be
increased.
When the huge swap cluster has been split already, we need to split the
PMD swap mapping and fallback to PTE copying.
When swap count continuation failed to allocate a page with GFP_ATOMIC, we
need to unlock the spinlock and try again with GFP_KERNEL.
Link: http://lkml.kernel.org/r/20180622035151.6676-16-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-swap-support-to-copy-pmd-swap-mapping-when-fork mm/huge_memory.c
--- a/mm/huge_memory.c~mm-thp-swap-support-to-copy-pmd-swap-mapping-when-fork
+++ a/mm/huge_memory.c
@@ -941,6 +941,7 @@ int copy_huge_pmd(struct mm_struct *dst_
if (unlikely(!pgtable))
goto out;
+retry:
dst_ptl = pmd_lock(dst_mm, dst_pmd);
src_ptl = pmd_lockptr(src_mm, src_pmd);
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
@@ -948,26 +949,67 @@ int copy_huge_pmd(struct mm_struct *dst_
ret = -EAGAIN;
pmd = *src_pmd;
-#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
if (unlikely(is_swap_pmd(pmd))) {
swp_entry_t entry = pmd_to_swp_entry(pmd);
- VM_BUG_ON(!is_pmd_migration_entry(pmd));
- if (is_write_migration_entry(entry)) {
- make_migration_entry_read(&entry);
- pmd = swp_entry_to_pmd(entry);
- if (pmd_swp_soft_dirty(*src_pmd))
- pmd = pmd_swp_mksoft_dirty(pmd);
- set_pmd_at(src_mm, addr, src_pmd, pmd);
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+ if (is_migration_entry(entry)) {
+ if (is_write_migration_entry(entry)) {
+ make_migration_entry_read(&entry);
+ pmd = swp_entry_to_pmd(entry);
+ if (pmd_swp_soft_dirty(*src_pmd))
+ pmd = pmd_swp_mksoft_dirty(pmd);
+ set_pmd_at(src_mm, addr, src_pmd, pmd);
+ }
+ add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ mm_inc_nr_ptes(dst_mm);
+ pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
+ set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+ ret = 0;
+ goto out_unlock;
}
- add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
- mm_inc_nr_ptes(dst_mm);
- pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
- set_pmd_at(dst_mm, addr, dst_pmd, pmd);
- ret = 0;
- goto out_unlock;
- }
#endif
+ if (thp_swap_supported() && !non_swap_entry(entry)) {
+ ret = swap_duplicate(&entry, true);
+ if (!ret) {
+ add_mm_counter(dst_mm, MM_SWAPENTS,
+ HPAGE_PMD_NR);
+ mm_inc_nr_ptes(dst_mm);
+ pgtable_trans_huge_deposit(dst_mm, dst_pmd,
+ pgtable);
+ set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+ /* make sure dst_mm is on swapoff's mmlist. */
+ if (unlikely(list_empty(&dst_mm->mmlist))) {
+ spin_lock(&mmlist_lock);
+ if (list_empty(&dst_mm->mmlist))
+ list_add(&dst_mm->mmlist,
+ &src_mm->mmlist);
+ spin_unlock(&mmlist_lock);
+ }
+ } else if (ret == -ENOTDIR) {
+ /*
+ * The swap cluster has been split, split the
+ * pmd map now
+ */
+ __split_huge_swap_pmd(vma, addr, src_pmd);
+ pte_free(dst_mm, pgtable);
+ } else if (ret == -ENOMEM) {
+ spin_unlock(src_ptl);
+ spin_unlock(dst_ptl);
+ ret = add_swap_count_continuation(entry,
+ GFP_KERNEL);
+ if (ret < 0) {
+ ret = -ENOMEM;
+ pte_free(dst_mm, pgtable);
+ goto out;
+ }
+ goto retry;
+ } else
+ VM_BUG_ON(1);
+ goto out_unlock;
+ }
+ VM_BUG_ON(1);
+ }
if (unlikely(!pmd_trans_huge(pmd))) {
pte_free(dst_mm, pgtable);
_
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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