The patch titled
Subject: pagemap: add mmap-exclusive bit for marking pages mapped only here
has been added to the -mm tree. Its filename is
pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Subject: pagemap: add mmap-exclusive bit for marking pages mapped only here
This patch sets bit 56 in pagemap if this page is mapped only once. It
allows to detect exclusively used pages without exposing PFN:
present file exclusive state
0 0 0 non-present
1 1 0 file page mapped somewhere else
1 1 1 file page mapped only here
1 0 0 anon non-CoWed page (shared with parent/child)
1 0 1 anon CoWed page (or never forked)
CoWed pages in (MAP_FILE | MAP_PRIVATE) areas are anon in this context.
MMap-exclusive bit doesn't reflect potential page-sharing via swapcache:
page could be mapped once but has several swap-ptes which point to it.
Application could detect that by swap bit in pagemap entry and touch that
pte via /proc/pid/mem to get real information.
See http://lkml.kernel.org/r/CAEVpBa+_RyACkhODZrRvQLs80iy0sqpdrd0AaP_-tgnX3Y9yNQ@xxxxxxxxxxxxxx
Requested by Mark Williamson.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Cc: Mark Williamson <mwilliamson@xxxxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/vm/pagemap.txt | 3 ++-
fs/proc/task_mmu.c | 14 +++++++++++++-
tools/vm/page-types.c | 10 ++++++++++
3 files changed, 25 insertions(+), 2 deletions(-)
diff -puN Documentation/vm/pagemap.txt~pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here Documentation/vm/pagemap.txt
--- a/Documentation/vm/pagemap.txt~pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here
+++ a/Documentation/vm/pagemap.txt
@@ -16,7 +16,8 @@ There are three components to pagemap:
* Bits 0-4 swap type if swapped
* Bits 5-54 swap offset if swapped
* Bit 55 pte is soft-dirty (see Documentation/vm/soft-dirty.txt)
- * Bits 56-60 zero
+ * Bit 56 page exlusively mapped
+ * Bits 57-60 zero
* Bit 61 page is file-page or shared-anon
* Bit 62 page swapped
* Bit 63 page present
diff -puN fs/proc/task_mmu.c~pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here
+++ a/fs/proc/task_mmu.c
@@ -950,6 +950,7 @@ struct pagemapread {
#define PM_PFRAME_BITS 55
#define PM_PFRAME_MASK GENMASK_ULL(PM_PFRAME_BITS - 1, 0)
#define PM_SOFT_DIRTY BIT_ULL(55)
+#define PM_MMAP_EXCLUSIVE BIT_ULL(56)
#define PM_FILE BIT_ULL(61)
#define PM_SWAP BIT_ULL(62)
#define PM_PRESENT BIT_ULL(63)
@@ -1037,6 +1038,8 @@ static pagemap_entry_t pte_to_pagemap_en
if (page && !PageAnon(page))
flags |= PM_FILE;
+ if (page && page_mapcount(page) == 1)
+ flags |= PM_MMAP_EXCLUSIVE;
if (vma->vm_flags & VM_SOFTDIRTY)
flags |= PM_SOFT_DIRTY;
@@ -1067,6 +1070,11 @@ static int pagemap_pmd_range(pmd_t *pmdp
* This if-check is just to prepare for future implementation.
*/
if (pmd_present(pmd)) {
+ struct page *page = pmd_page(pmd);
+
+ if (page_mapcount(page) == 1)
+ flags |= PM_MMAP_EXCLUSIVE;
+
flags |= PM_PRESENT;
if (pm->show_pfn)
frame = pmd_pfn(pmd) +
@@ -1132,6 +1140,9 @@ static int pagemap_hugetlb_range(pte_t *
if (!PageAnon(page))
flags |= PM_FILE;
+ if (page_mapcount(page) == 1)
+ flags |= PM_MMAP_EXCLUSIVE;
+
flags |= PM_PRESENT;
if (pm->show_pfn)
frame = pte_pfn(pte) +
@@ -1164,7 +1175,8 @@ static int pagemap_hugetlb_range(pte_t *
* Bits 0-4 swap type if swapped
* Bits 5-54 swap offset if swapped
* Bit 55 pte is soft-dirty (see Documentation/vm/soft-dirty.txt)
- * Bits 56-60 zero
+ * Bit 56 page exclusively mapped
+ * Bits 57-60 zero
* Bit 61 page is file-page or shared-anon
* Bit 62 page swapped
* Bit 63 page present
diff -puN tools/vm/page-types.c~pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here tools/vm/page-types.c
--- a/tools/vm/page-types.c~pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here
+++ a/tools/vm/page-types.c
@@ -62,6 +62,7 @@
#define PM_PFRAME_MASK ((1LL << PM_PFRAME_BITS) - 1)
#define PM_PFRAME(x) ((x) & PM_PFRAME_MASK)
#define PM_SOFT_DIRTY (1ULL << 55)
+#define PM_MMAP_EXCLUSIVE (1ULL << 56)
#define PM_FILE (1ULL << 61)
#define PM_SWAP (1ULL << 62)
#define PM_PRESENT (1ULL << 63)
@@ -91,6 +92,8 @@
#define KPF_SLOB_FREE 49
#define KPF_SLUB_FROZEN 50
#define KPF_SLUB_DEBUG 51
+#define KPF_FILE 62
+#define KPF_MMAP_EXCLUSIVE 63
#define KPF_ALL_BITS ((uint64_t)~0ULL)
#define KPF_HACKERS_BITS (0xffffULL << 32)
@@ -140,6 +143,9 @@ static const char * const page_flag_name
[KPF_SLOB_FREE] = "P:slob_free",
[KPF_SLUB_FROZEN] = "A:slub_frozen",
[KPF_SLUB_DEBUG] = "E:slub_debug",
+
+ [KPF_FILE] = "F:file",
+ [KPF_MMAP_EXCLUSIVE] = "1:mmap_exclusive",
};
@@ -443,6 +449,10 @@ static uint64_t expand_overloaded_flags(
if (pme & PM_SOFT_DIRTY)
flags |= BIT(SOFTDIRTY);
+ if (pme & PM_FILE)
+ flags |= BIT(FILE);
+ if (pme & PM_MMAP_EXCLUSIVE)
+ flags |= BIT(MMAP_EXCLUSIVE);
return flags;
}
_
Patches currently in -mm which might be from khlebnikov@xxxxxxxxxxxxxx are
pagemap-check-permissions-and-capabilities-at-open-time.patch
pagemap-switch-to-the-new-format-and-do-some-cleanup.patch
pagemap-rework-hugetlb-and-thp-report.patch
pagemap-hide-physical-addresses-from-non-privileged-users.patch
pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here.patch
pagemap-add-mmap-exclusive-bit-for-marking-pages-mapped-only-here-fix.patch
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