The patch titled
Subject: rmap: extend try_to_unmap() to be usable by split_huge_page()
has been added to the -mm tree. Its filename is
rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page.patch
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: rmap: extend try_to_unmap() to be usable by split_huge_page()
Add support for two ttu_flags:
- TTU_SPLIT_HUGE_PMD would split PMD if it's there, before trying to
unmap page;
- TTU_RMAP_LOCKED indicates that caller holds relevant rmap lock;
Also, change rwc->done to !page_mapcount() instead of !page_mapped().
try_to_unmap() works on pte level, so we are really interested in the
mappedness of this small page rather than of the compound page it's a part
of.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/huge_mm.h | 7 +++++++
include/linux/rmap.h | 3 +++
mm/huge_memory.c | 5 +----
mm/rmap.c | 24 ++++++++++++++++--------
4 files changed, 27 insertions(+), 12 deletions(-)
diff -puN include/linux/huge_mm.h~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page include/linux/huge_mm.h
--- a/include/linux/huge_mm.h~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page
+++ a/include/linux/huge_mm.h
@@ -106,6 +106,9 @@ void __split_huge_pmd(struct vm_area_str
__split_huge_pmd(__vma, __pmd, __address); \
} while (0)
+
+void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address);
+
#if HPAGE_PMD_ORDER >= MAX_ORDER
#error "hugepages can't be allocated by the buddy allocator"
#endif
@@ -173,6 +176,10 @@ static inline int split_huge_page(struct
static inline void deferred_split_huge_page(struct page *page) {}
#define split_huge_pmd(__vma, __pmd, __address) \
do { } while (0)
+
+static inline void split_huge_pmd_address(struct vm_area_struct *vma,
+ unsigned long address) {}
+
static inline int hugepage_madvise(struct vm_area_struct *vma,
unsigned long *vm_flags, int advice)
{
diff -puN include/linux/rmap.h~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page include/linux/rmap.h
--- a/include/linux/rmap.h~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page
+++ a/include/linux/rmap.h
@@ -86,6 +86,7 @@ enum ttu_flags {
TTU_MIGRATION = 2, /* migration mode */
TTU_MUNLOCK = 4, /* munlock mode */
TTU_LZFREE = 8, /* lazy free mode */
+ TTU_SPLIT_HUGE_PMD = 16, /* split huge PMD if any */
TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
@@ -93,6 +94,8 @@ enum ttu_flags {
TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible
* and caller guarantees they will
* do a final flush if necessary */
+ TTU_RMAP_LOCKED = (1 << 12) /* do not grab rmap lock:
+ * caller holds it */
};
#ifdef CONFIG_MMU
diff -puN mm/huge_memory.c~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page mm/huge_memory.c
--- a/mm/huge_memory.c~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page
+++ a/mm/huge_memory.c
@@ -3006,15 +3006,12 @@ out:
}
}
-static void split_huge_pmd_address(struct vm_area_struct *vma,
- unsigned long address)
+void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
- VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
-
pgd = pgd_offset(vma->vm_mm, address);
if (!pgd_present(*pgd))
return;
diff -puN mm/rmap.c~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page mm/rmap.c
--- a/mm/rmap.c~rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page
+++ a/mm/rmap.c
@@ -1431,6 +1431,8 @@ static int try_to_unmap_one(struct page
if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
goto out;
+ if (flags & TTU_SPLIT_HUGE_PMD)
+ split_huge_pmd_address(vma, address);
pte = page_check_address(page, mm, address, &ptl, 0);
if (!pte)
goto out;
@@ -1576,10 +1578,10 @@ static bool invalid_migration_vma(struct
return is_vma_temporary_stack(vma);
}
-static int page_not_mapped(struct page *page)
+static int page_mapcount_is_zero(struct page *page)
{
- return !page_mapped(page);
-};
+ return !page_mapcount(page);
+}
/**
* try_to_unmap - try to remove all page table mappings to a page
@@ -1606,12 +1608,10 @@ int try_to_unmap(struct page *page, enum
struct rmap_walk_control rwc = {
.rmap_one = try_to_unmap_one,
.arg = &rp,
- .done = page_not_mapped,
+ .done = page_mapcount_is_zero,
.anon_lock = page_lock_anon_vma_read,
};
- VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page);
-
/*
* During exec, a temporary VMA is setup and later moved.
* The VMA is moved under the anon_vma lock but not the
@@ -1623,9 +1623,12 @@ int try_to_unmap(struct page *page, enum
if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page))
rwc.invalid_vma = invalid_migration_vma;
- ret = rmap_walk(page, &rwc);
+ if (flags & TTU_RMAP_LOCKED)
+ ret = rmap_walk_locked(page, &rwc);
+ else
+ ret = rmap_walk(page, &rwc);
- if (ret != SWAP_MLOCK && !page_mapped(page)) {
+ if (ret != SWAP_MLOCK && !page_mapcount(page)) {
ret = SWAP_SUCCESS;
if (rp.lazyfreed && !PageDirty(page))
ret = SWAP_LZFREE;
@@ -1633,6 +1636,11 @@ int try_to_unmap(struct page *page, enum
return ret;
}
+static int page_not_mapped(struct page *page)
+{
+ return !page_mapped(page);
+};
+
/**
* try_to_munlock - try to munlock a page
* @page: the page to be munlocked
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-thp-fix-migration-of-pte-mapped-transparent-huge-pages.patch
thp-cleanup-split_huge_page.patch
thp-vmstats-count-deferred-split-events.patch
mm-tracing-refresh-__def_vmaflag_names.patch
mm-cleanup-pte_alloc-interfaces.patch
rmap-introduce-rmap_walk_locked.patch
rmap-extend-try_to_unmap-to-be-usable-by-split_huge_page.patch
mm-make-remove_migration_ptes-beyond-mm-migrationc.patch
thp-rewrite-freeze_page-unfreeze_page-with-generic-rmap-walkers.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-2.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-3.patch
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