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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2015-09-08 15:00:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-08 15:35:28 -0700
commit77bb499bb60f4b79cca7d139c8041662860fcf87 (patch)
tree6a1565ab551fcf8c04b4f38c37b085bbf0829da5 /tools
parent1c90308e7a77af6742a97d1021cca923b23b7f0d (diff)
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@mail.gmail.com Requested by Mark Williamson. [akpm@linux-foundation.org: fix spello] Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Mark Williamson <mwilliamson@undo-software.com> Tested-by: Mark Williamson <mwilliamson@undo-software.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/vm/page-types.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
index 603ec916716b..7f73fa32a590 100644
--- a/tools/vm/page-types.c
+++ b/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_names[] = {
[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(uint64_t flags, uint64_t pme)
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;
}

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