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    Subject[PATCH v4 09/10] iommu: observability of the IOMMU allocations
    Date
    Add NR_IOMMU_PAGES into node_stat_item that counts number of pages
    that are allocated by the IOMMU subsystem.

    The allocations can be view per-node via:
    /sys/devices/system/node/nodeN/vmstat.

    For example:

    $ grep iommu /sys/devices/system/node/node*/vmstat
    /sys/devices/system/node/node0/vmstat:nr_iommu_pages 106025
    /sys/devices/system/node/node1/vmstat:nr_iommu_pages 3464

    The value is in page-count, therefore, in the above example
    the iommu allocations amount to ~428M.

    Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
    Acked-by: David Rientjes <rientjes@google.com>
    Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
    ---
    drivers/iommu/iommu-pages.h | 30 ++++++++++++++++++++++++++++++
    include/linux/mmzone.h | 3 +++
    mm/vmstat.c | 3 +++
    3 files changed, 36 insertions(+)

    diff --git a/drivers/iommu/iommu-pages.h b/drivers/iommu/iommu-pages.h
    index c412d0aaa399..7336f976b641 100644
    --- a/drivers/iommu/iommu-pages.h
    +++ b/drivers/iommu/iommu-pages.h
    @@ -17,6 +17,30 @@
    * state can be rather large, i.e. multiple gigabytes in size.
    */

    +/**
    + * __iommu_alloc_account - account for newly allocated page.
    + * @page: head struct page of the page.
    + * @order: order of the page
    + */
    +static inline void __iommu_alloc_account(struct page *page, int order)
    +{
    + const long pgcnt = 1l << order;
    +
    + mod_node_page_state(page_pgdat(page), NR_IOMMU_PAGES, pgcnt);
    +}
    +
    +/**
    + * __iommu_free_account - account a page that is about to be freed.
    + * @page: head struct page of the page.
    + * @order: order of the page
    + */
    +static inline void __iommu_free_account(struct page *page, int order)
    +{
    + const long pgcnt = 1l << order;
    +
    + mod_node_page_state(page_pgdat(page), NR_IOMMU_PAGES, -pgcnt);
    +}
    +
    /**
    * __iommu_alloc_pages_node - allocate a zeroed page of a given order from
    * specific NUMA node.
    @@ -35,6 +59,8 @@ static inline struct page *__iommu_alloc_pages_node(int nid, gfp_t gfp,
    if (unlikely(!page))
    return NULL;

    + __iommu_alloc_account(page, order);
    +
    return page;
    }

    @@ -53,6 +79,8 @@ static inline struct page *__iommu_alloc_pages(gfp_t gfp, int order)
    if (unlikely(!page))
    return NULL;

    + __iommu_alloc_account(page, order);
    +
    return page;
    }

    @@ -89,6 +117,7 @@ static inline void __iommu_free_pages(struct page *page, int order)
    if (!page)
    return;

    + __iommu_free_account(page, order);
    __free_pages(page, order);
    }

    @@ -197,6 +226,7 @@ static inline void iommu_free_pages_list(struct list_head *page)
    struct page *p = list_entry(page->prev, struct page, lru);

    list_del(&p->lru);
    + __iommu_free_account(p, 0);
    put_page(p);
    }
    }
    diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
    index a497f189d988..bb6bc504915a 100644
    --- a/include/linux/mmzone.h
    +++ b/include/linux/mmzone.h
    @@ -203,6 +203,9 @@ enum node_stat_item {
    #endif
    NR_PAGETABLE, /* used for pagetables */
    NR_SECONDARY_PAGETABLE, /* secondary pagetables, e.g. KVM pagetables */
    +#ifdef CONFIG_IOMMU_SUPPORT
    + NR_IOMMU_PAGES, /* # of pages allocated by IOMMU */
    +#endif
    #ifdef CONFIG_SWAP
    NR_SWAPCACHE,
    #endif
    diff --git a/mm/vmstat.c b/mm/vmstat.c
    index db79935e4a54..8507c497218b 100644
    --- a/mm/vmstat.c
    +++ b/mm/vmstat.c
    @@ -1242,6 +1242,9 @@ const char * const vmstat_text[] = {
    #endif
    "nr_page_table_pages",
    "nr_sec_page_table_pages",
    +#ifdef CONFIG_IOMMU_SUPPORT
    + "nr_iommu_pages",
    +#endif
    #ifdef CONFIG_SWAP
    "nr_swapcached",
    #endif
    --
    2.43.0.594.gd9cf4e227d-goog

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