Live-lock issues in memory allocator.

    * Debug tool for PageManager.
    * Support PageMgr allocations of non-2^k size.
    * Switch page-allocation to always be in kernel-mode.

    While investigating issue 44511, I noticed two problesm with the
    memory page allocator (PageManager).  First, the allocator did
    not support allocations of pages which were not a power of 2,
    which would result in pages appearing to "leak".  Second, in
    situations where a large allocation was requested and there was
    not a large chunk available, the allocation would enter a
    live-lock condition where coalescing would never occur.

    Switched the PageManager so that all allocations happen in
    kernel space.  This allows us to force memory-release operations
    on the syscall path when we are out of memory and also put in
    place a task_yield call which will allow coalescing to eventually
    occur.  Issue 44523 is suppose to fully resolve any of these
    live-lock paths.

RTC: 44511
Change-Id: Ifefd5d0996ee6914e291c862fac0c7b76980717f
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/1330
Tested-by: Jenkins Server
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>

1 files changed, 10 insertions, 12 deletions

diff --git a/src/include/kernel/pagemgr.H b/src/include/kernel/pagemgr.H
index 6676a469c..93cd82bb5 100644
--- a/src/include/kernel/pagemgr.H
+++ b/src/include/kernel/pagemgr.H
@@ -54,7 +54,7 @@ class PageManagerCore
         /**
          * Default Constructor
          */
-        PageManagerCore() 
+        PageManagerCore()
             : iv_available(0) {}
 
         /**
@@ -76,7 +76,7 @@ class PageManagerCore
          * @return a pointer to the requested allocation | NULL
          * if the request could not be satisfied.
          */
-        page_t  * allocatePage( size_t i_pageCount );
+        page_t * allocatePage( size_t i_pageCount );
 
         /**
          * Return page allocations to the page manager
@@ -136,9 +136,10 @@ class PageManager
         /**
          * Allocate pages
          * @param[in] n, Requested allocation in pages
+         * @param[in] userspace - Request to allocate came from userspace
          * @return pointer to requested memory
          */
-        static void* allocatePage(size_t n = 1);
+        static void* allocatePage(size_t n = 1, bool userspace = false);
 
         /**
          * Return pages to the pagemanager
@@ -170,6 +171,9 @@ class PageManager
         {
             MEMLEN = VmmManager::MBOX_DMA_ADDR,
             RESERVED_PAGES = 4,
+
+            LOWMEM_NORM_LIMIT = 16,
+            LOWMEM_CRIT_LIMIT = 5,
         };
 
         static size_t cv_coalesce_count;        //!< running coalesced counter
@@ -182,15 +186,9 @@ class PageManager
 
     private:
 
-        void* _allocatePage(size_t);    //!< see allocatePage()
-        void _freePage(void*, size_t);  //!< see freePage()
-        void _coalesce( void );         //!< see coalesce()
-
-        /**
-         * Query if in kernel mode
-         * @return [true | false]
-         */
-        bool queryKernelMode() const;
+        void* _allocatePage(size_t,bool);    //!< see allocatePage()
+        void _freePage(void*, size_t);       //!< see freePage()
+        void _coalesce( void );              //!< see coalesce()
 
         /** see queryAvail() */
         ALWAYS_INLINE uint64_t _queryAvail() const