Re: [Xen-devel] [PATCH v4 1/3] mm: keep PGC_extra pages on a separate list

[Julien Grall]

On 18/03/2020 17:32, Paul Durrant wrote:

This patch adds a new page_list_head into struct domain to hold PGC_extra
pages. This avoids them getting confused with 'normal' domheap pages where
the domain's page_list is walked.

A new dump loop is also added to dump_pageframe_info() to unconditionally
dump the 'extra page list'.

Signed-off-by: Paul Durrant <p...@xen.org>
Reviewed-by: Jan Beulich <jbeul...@suse.com>

Acked-by: Julien Grall <jul...@xen.org>

---
Cc: Andrew Cooper <andrew.coop...@citrix.com>
Cc: George Dunlap <george.dun...@citrix.com>
Cc: Ian Jackson <ian.jack...@eu.citrix.com>
Cc: Julien Grall <jul...@xen.org>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Wei Liu <w...@xen.org>
Cc: "Roger Pau Monné" <roger....@citrix.com>

v7:
  - Cosmetic changes

v6:
  - New in v6
---
  xen/arch/x86/domain.c    |  9 +++++++++
  xen/common/domain.c      |  1 +
  xen/common/page_alloc.c  |  2 +-
  xen/include/asm-x86/mm.h |  6 ++----
  xen/include/xen/mm.h     |  5 ++---
  xen/include/xen/sched.h  | 13 +++++++++++++
  6 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index caf2ecad7e..683bc619aa 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -251,12 +251,21 @@ void dump_pageframe_info(struct domain *d)
          p2m_pod_dump_data(d);

spin_lock(&d->page_alloc_lock);

+
      page_list_for_each ( page, &d->xenpage_list )
      {
          printk("    XenPage %p: caf=%08lx, taf=%" PRtype_info "\n",
                 _p(mfn_x(page_to_mfn(page))),
                 page->count_info, page->u.inuse.type_info);
      }
+
+    page_list_for_each ( page, &d->extra_page_list )
+    {
+        printk("    ExtraPage %p: caf=%08lx, taf=%" PRtype_info "\n",
+               _p(mfn_x(page_to_mfn(page))),
+               page->count_info, page->u.inuse.type_info);
+    }
+
      spin_unlock(&d->page_alloc_lock);
  }

diff --git a/xen/common/domain.c b/xen/common/domain.c

index b4eb476a9c..3dcd73f67c 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -403,6 +403,7 @@ struct domain *domain_create(domid_t domid,
      spin_lock_init_prof(d, page_alloc_lock);
      spin_lock_init(&d->hypercall_deadlock_mutex);
      INIT_PAGE_LIST_HEAD(&d->page_list);
+    INIT_PAGE_LIST_HEAD(&d->extra_page_list);
      INIT_PAGE_LIST_HEAD(&d->xenpage_list);

spin_lock_init(&d->node_affinity_lock);

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 76d37226df..10b7aeca48 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2314,7 +2314,7 @@ int assign_pages(
          smp_wmb(); /* Domain pointer must be visible before updating refcnt. 
*/
          pg[i].count_info =
              (pg[i].count_info & PGC_extra) | PGC_allocated | 1;
-        page_list_add_tail(&pg[i], &d->page_list);
+        page_list_add_tail(&pg[i], page_to_list(d, &pg[i]));
      }

out:

diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index a06b2fb81f..1fa334b306 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -629,10 +629,8 @@ typedef struct mm_rwlock {
      const char        *locker_function; /* func that took it */
  } mm_rwlock_t;

-#define arch_free_heap_page(d, pg) \

-    page_list_del2(pg, is_xen_heap_page(pg) ?                           \
-                       &(d)->xenpage_list : &(d)->page_list,            \
-                   &(d)->arch.relmem_list)
+#define arch_free_heap_page(d, pg) \
+    page_list_del2(pg, page_to_list(d, pg), &(d)->arch.relmem_list)

extern const char zero_page[]; diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h

index d0d095d9c7..a163c201e2 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -583,9 +583,8 @@ static inline unsigned int get_order_from_pages(unsigned 
long nr_pages)
  void scrub_one_page(struct page_info *);

#ifndef arch_free_heap_page

-#define arch_free_heap_page(d, pg)                      \
-    page_list_del(pg, is_xen_heap_page(pg) ?            \
-                      &(d)->xenpage_list : &(d)->page_list)
+#define arch_free_heap_page(d, pg) \
+    page_list_del(pg, page_to_list(d, pg))
  #endif

int xenmem_add_to_physmap_one(struct domain *d, unsigned int space,

diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index e6813288ab..4b78291d51 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -329,6 +329,7 @@ struct domain

spinlock_t page_alloc_lock; /* protects all the following fields */

      struct page_list_head page_list;  /* linked list */
+    struct page_list_head extra_page_list; /* linked list (size extra_pages) */
      struct page_list_head xenpage_list; /* linked list (size xenheap_pages) */

/*

@@ -512,6 +513,18 @@ struct domain
  #endif
  };

+static inline struct page_list_head *page_to_list(

+    struct domain *d, const struct page_info *pg)
+{
+    if ( is_xen_heap_page(pg) )
+        return &d->xenpage_list;
+
+    if ( pg->count_info & PGC_extra )
+        return &d->extra_page_list;
+
+    return &d->page_list;
+}
+
  /* Return number of pages currently posessed by the domain */
  static inline unsigned int domain_tot_pages(const struct domain *d)
  {

--
Julien Grall