Re: [PATCH 5/7] mm: introduce common page state for ballooned memory

From: Rafael Aquini
Date: Wed Aug 20 2014 - 19:46:28 EST

On Wed, Aug 20, 2014 at 07:04:58PM +0400, Konstantin Khlebnikov wrote:
> This patch adds page state PageBallon() and functions __Set/ClearPageBalloon.
> Like PageBuddy() PageBalloon() looks like page-flag but actually this is special
> state of page->_mapcount counter. There is no conflict because ballooned pages
> cannot be mapped and cannot be in buddy allocator.
>
> Ballooned pages are counted in vmstat counter NR_BALLOON_PAGES, it's shown them
> in /proc/meminfo and /proc/meminfo. Also this patch it exports PageBallon into
> userspace via /proc/kpageflags as KPF_BALLOON.
>
> All this code including mm/balloon_compaction.o is under CONFIG_MEMORY_BALLOON,
> it should be selected by ballooning driver which want use this feature.
>

Very nice overhaul Konstantin!
Please, consider the nits I have below:


> Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
> ---
> Documentation/filesystems/proc.txt | 2 ++
> drivers/base/node.c | 16 ++++++++++------
> drivers/virtio/Kconfig | 1 +
> fs/proc/meminfo.c | 6 ++++++
> fs/proc/page.c | 3 +++
> include/linux/mm.h | 10 ++++++++++
> include/linux/mmzone.h | 3 +++
> include/uapi/linux/kernel-page-flags.h | 1 +
> mm/Kconfig | 5 +++++
> mm/Makefile | 3 ++-
> mm/balloon_compaction.c | 14 ++++++++++++++
> mm/vmstat.c | 8 +++++++-
> tools/vm/page-types.c | 1 +
> 13 files changed, 65 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
> index eb8a10e..154a345 100644
> --- a/Documentation/filesystems/proc.txt
> +++ b/Documentation/filesystems/proc.txt
> @@ -796,6 +796,7 @@ VmallocTotal: 112216 kB
> VmallocUsed: 428 kB
> VmallocChunk: 111088 kB
> AnonHugePages: 49152 kB
> +BalloonPages: 0 kB
>
> MemTotal: Total usable ram (i.e. physical ram minus a few reserved
> bits and the kernel binary code)
> @@ -838,6 +839,7 @@ MemAvailable: An estimate of how much memory is available for starting new
> Writeback: Memory which is actively being written back to the disk
> AnonPages: Non-file backed pages mapped into userspace page tables
> AnonHugePages: Non-file backed huge pages mapped into userspace page tables
> +BalloonPages: Memory which was ballooned, not included into MemTotal
> Mapped: files which have been mmaped, such as libraries
> Slab: in-kernel data structures cache
> SReclaimable: Part of Slab, that might be reclaimed, such as caches
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index c6d3ae0..59e565c 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -120,6 +120,9 @@ static ssize_t node_read_meminfo(struct device *dev,
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> "Node %d AnonHugePages: %8lu kB\n"
> #endif
> +#ifdef CONFIG_MEMORY_BALLOON
> + "Node %d BalloonPages: %8lu kB\n"
> +#endif
> ,
> nid, K(node_page_state(nid, NR_FILE_DIRTY)),
> nid, K(node_page_state(nid, NR_WRITEBACK)),
> @@ -136,14 +139,15 @@ static ssize_t node_read_meminfo(struct device *dev,
> nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE) +
> node_page_state(nid, NR_SLAB_UNRECLAIMABLE)),
> nid, K(node_page_state(nid, NR_SLAB_RECLAIMABLE)),
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE))
> - , nid,
> - K(node_page_state(nid, NR_ANON_TRANSPARENT_HUGEPAGES) *
> - HPAGE_PMD_NR));
> -#else
> - nid, K(node_page_state(nid, NR_SLAB_UNRECLAIMABLE)));
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> + ,nid, K(node_page_state(nid,
> + NR_ANON_TRANSPARENT_HUGEPAGES) * HPAGE_PMD_NR)
> +#endif
> +#ifdef CONFIG_MEMORY_BALLOON
> + ,nid, K(node_page_state(nid, NR_BALLOON_PAGES))
> #endif
> + );
> n += hugetlb_report_node_meminfo(nid, buf + n);
> return n;
> }
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index c6683f2..00b2286 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -25,6 +25,7 @@ config VIRTIO_PCI
> config VIRTIO_BALLOON
> tristate "Virtio balloon driver"
> depends on VIRTIO
> + select MEMORY_BALLOON
> ---help---
> This driver supports increasing and decreasing the amount
> of memory within a KVM guest.
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> index aa1eee0..f897fbf 100644
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -138,6 +138,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> "AnonHugePages: %8lu kB\n"
> #endif
> +#ifdef CONFIG_MEMORY_BALLOON
> + "BalloonPages: %8lu kB\n"
> +#endif
> ,
> K(i.totalram),
> K(i.freeram),
> @@ -193,6 +196,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
> ,K(global_page_state(NR_ANON_TRANSPARENT_HUGEPAGES) *
> HPAGE_PMD_NR)
> #endif
> +#ifdef CONFIG_MEMORY_BALLOON
> + ,K(global_page_state(NR_BALLOON_PAGES))
> +#endif
> );
>
> hugetlb_report_meminfo(m);
> diff --git a/fs/proc/page.c b/fs/proc/page.c
> index e647c55..1e3187d 100644
> --- a/fs/proc/page.c
> +++ b/fs/proc/page.c
> @@ -133,6 +133,9 @@ u64 stable_page_flags(struct page *page)
> if (PageBuddy(page))
> u |= 1 << KPF_BUDDY;
>
> + if (PageBalloon(page))
> + u |= 1 << KPF_BALLOON;
> +
> u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
>
> u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 8981cc8..d2dd497 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -553,6 +553,16 @@ static inline void __ClearPageBuddy(struct page *page)
> atomic_set(&page->_mapcount, -1);
> }
>
> +#define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
> +
> +static inline int PageBalloon(struct page *page)
> +{
> + return IS_ENABLED(CONFIG_MEMORY_BALLOON) &&
> + atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
> +}
> +void __SetPageBalloon(struct page *page);
> +void __ClearPageBalloon(struct page *page);
> +

1) I think you should consider the following here:

-void __SetPageBalloon(struct page *page);
-void __ClearPageBalloon(struct page *page);
+
+static inline void __SetPageBalloon(struct page *page)
+{
+#ifdef CONFIG_MEMORY_BALLOON
+ VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
+ atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
+#endif
+}
+
+static inline void __ClearPageBalloon(struct page *page)
+{
+#ifdef CONFIG_MEMORY_BALLOON
+ VM_BUG_ON_PAGE(!PageBalloon(page), page);
+ atomic_set(&page->_mapcount, -1);
+#endif
+}




> void put_page(struct page *page);
> void put_pages_list(struct list_head *pages);
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 318df70..d88fd01 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -157,6 +157,9 @@ enum zone_stat_item {
> WORKINGSET_NODERECLAIM,
> NR_ANON_TRANSPARENT_HUGEPAGES,
> NR_FREE_CMA_PAGES,
> +#ifdef CONFIG_MEMORY_BALLOON
> + NR_BALLOON_PAGES,
> +#endif
> NR_VM_ZONE_STAT_ITEMS };
>
> /*
> diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h
> index 5116a0e..2f96d23 100644
> --- a/include/uapi/linux/kernel-page-flags.h
> +++ b/include/uapi/linux/kernel-page-flags.h
> @@ -31,6 +31,7 @@
>
> #define KPF_KSM 21
> #define KPF_THP 22
> +#define KPF_BALLOON 23
>
>
> #endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 886db21..72e0db0 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -228,6 +228,11 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
> boolean
>
> #
> +# support for memory ballooning
> +config MEMORY_BALLOON
> + boolean
> +
> +#
> # support for memory balloon compaction
> config BALLOON_COMPACTION
> bool "Allow for balloon memory compaction/migration"
> diff --git a/mm/Makefile b/mm/Makefile
> index 632ae77..2d33d7f 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -16,7 +16,7 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
> readahead.o swap.o truncate.o vmscan.o shmem.o \
> util.o mmzone.o vmstat.o backing-dev.o \
> mm_init.o mmu_context.o percpu.o slab_common.o \
> - compaction.o balloon_compaction.o vmacache.o \
> + compaction.o vmacache.o \
> interval_tree.o list_lru.o workingset.o \
> iov_iter.o $(mmu-y)
>
> @@ -64,3 +64,4 @@ obj-$(CONFIG_ZBUD) += zbud.o
> obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
> obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
> obj-$(CONFIG_CMA) += cma.o
> +obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
> index 6e45a50..533c567 100644
> --- a/mm/balloon_compaction.c
> +++ b/mm/balloon_compaction.c
> @@ -10,6 +10,20 @@
> #include <linux/export.h>
> #include <linux/balloon_compaction.h>
>
> +void __SetPageBalloon(struct page *page)
> +{
> + VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
> + atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
> + inc_zone_page_state(page, NR_BALLOON_PAGES);
> +}
> +
> +void __ClearPageBalloon(struct page *page)
> +{
> + VM_BUG_ON_PAGE(!PageBalloon(page), page);
> + atomic_set(&page->_mapcount, -1);
> + dec_zone_page_state(page, NR_BALLOON_PAGES);
> +}
> +

and if you go with (1), here:
-void __SetPageBalloon(struct page *page)
-{
- VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
- atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
- inc_zone_page_state(page, NR_BALLOON_PAGES);
-}
-
-void __ClearPageBalloon(struct page *page)
-{
- VM_BUG_ON_PAGE(!PageBalloon(page), page);
- atomic_set(&page->_mapcount, -1);
- dec_zone_page_state(page, NR_BALLOON_PAGES);
-}


> /*
> * balloon_devinfo_alloc - allocates a balloon device information descriptor.
> * @balloon_dev_descriptor: pointer to reference the balloon device which
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index e9ab104..6e704cc 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -735,7 +735,7 @@ static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
> TEXT_FOR_HIGHMEM(xx) xx "_movable",
>
> const char * const vmstat_text[] = {
> - /* Zoned VM counters */
> + /* enum zone_stat_item countes */
> "nr_free_pages",
> "nr_alloc_batch",
> "nr_inactive_anon",
> @@ -778,10 +778,16 @@ const char * const vmstat_text[] = {
> "workingset_nodereclaim",
> "nr_anon_transparent_hugepages",
> "nr_free_cma",
> +#ifdef CONFIG_MEMORY_BALLOON
> + "nr_balloon_pages",
> +#endif
> +
> + /* enum writeback_stat_item counters */
> "nr_dirty_threshold",
> "nr_dirty_background_threshold",
>
> #ifdef CONFIG_VM_EVENT_COUNTERS
> + /* enum vm_event_item counters */
> "pgpgin",
> "pgpgout",
> "pswpin",
> diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
> index c4d6d2e..264fbc2 100644
> --- a/tools/vm/page-types.c
> +++ b/tools/vm/page-types.c
> @@ -132,6 +132,7 @@ static const char * const page_flag_names[] = {
> [KPF_NOPAGE] = "n:nopage",
> [KPF_KSM] = "x:ksm",
> [KPF_THP] = "t:thp",
> + [KPF_BALLOON] = "o:balloon",
>
> [KPF_RESERVED] = "r:reserved",
> [KPF_MLOCKED] = "m:mlocked",
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/