mem: prevent preallocated pages from being freed

It is common sense to expect for DPDK process to not deallocate any
pages that were preallocated by "-m" or "--socket-mem" flags - yet,
currently, DPDK memory subsystem will do exactly that once it finds
that the pages are unused.

Fix this by marking pages as unfreebale, and preventing malloc from
ever trying to free them.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Tested-by: Santosh Shukla <santosh.shukla@caviumnetworks.com>
Tested-by: Hemant Agrawal <hemant.agrawal@nxp.com>
Tested-by: Gowrishankar Muthukrishnan <gowrishankar.m@linux.vnet.ibm.com>

diff --git a/lib/librte_eal/common/include/rte_memory.h b/lib/librte_eal/common/include/rte_memory.h
index 01e7548..1e35cb2 100644 (file)
--- a/lib/librte_eal/common/include/rte_memory.h
+++ b/lib/librte_eal/common/include/rte_memory.h
@@ -83,6 +83,8 @@ typedef uint64_t rte_iova_t;
 /**
  * Physical memory segment descriptor.
  */
+#define RTE_MEMSEG_FLAG_DO_NOT_FREE (1 << 0)
+/**< Prevent this segment from being freed back to the OS. */
 struct rte_memseg {
        RTE_STD_C11
        union {
@@ -99,6 +101,7 @@ struct rte_memseg {
        int32_t socket_id;          /**< NUMA socket ID. */
        uint32_t nchannel;          /**< Number of channels. */
        uint32_t nrank;             /**< Number of ranks. */
+       uint32_t flags;             /**< Memseg-specific flags */
 } __rte_packed;
 
 /**

diff --git a/lib/librte_eal/common/malloc_heap.c b/lib/librte_eal/common/malloc_heap.c
index f8daf84..41c14a8 100644 (file)
--- a/lib/librte_eal/common/malloc_heap.c
+++ b/lib/librte_eal/common/malloc_heap.c
@@ -606,6 +606,7 @@ malloc_heap_free(struct malloc_elem *elem)
        void *start, *aligned_start, *end, *aligned_end;
        size_t len, aligned_len, page_sz;
        struct rte_memseg_list *msl;
+       unsigned int i, n_segs;
        int ret;
 
        if (!malloc_elem_cookies_ok(elem) || elem->state != ELEM_BUSY)
@@ -647,6 +648,28 @@ malloc_heap_free(struct malloc_elem *elem)
        if (aligned_len < page_sz)
                goto free_unlock;
 
+       /* we can free something. however, some of these pages may be marked as
+        * unfreeable, so also check that as well
+        */
+       n_segs = aligned_len / page_sz;
+       for (i = 0; i < n_segs; i++) {
+               const struct rte_memseg *tmp =
+                               rte_mem_virt2memseg(aligned_start, msl);
+
+               if (tmp->flags & RTE_MEMSEG_FLAG_DO_NOT_FREE) {
+                       /* this is an unfreeable segment, so move start */
+                       aligned_start = RTE_PTR_ADD(tmp->addr, tmp->len);
+               }
+       }
+
+       /* recalculate length and number of segments */
+       aligned_len = RTE_PTR_DIFF(aligned_end, aligned_start);
+       n_segs = aligned_len / page_sz;
+
+       /* check if we can still free some pages */
+       if (n_segs == 0)
+               goto free_unlock;
+
        rte_rwlock_write_lock(&mcfg->memory_hotplug_lock);
 
        /*

diff --git a/lib/librte_eal/linuxapp/eal/eal_memalloc.c b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
index 8063fe3..1f553dd 100644 (file)
--- a/lib/librte_eal/linuxapp/eal/eal_memalloc.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
@@ -807,6 +807,13 @@ eal_memalloc_free_seg_bulk(struct rte_memseg **ms, int n_segs)
                struct free_walk_param wa;
                int i, walk_res;
 
+               /* if this page is marked as unfreeable, fail */
+               if (cur->flags & RTE_MEMSEG_FLAG_DO_NOT_FREE) {
+                       RTE_LOG(DEBUG, EAL, "Page is not allowed to be freed\n");
+                       ret = -1;
+                       continue;
+               }
+
                memset(&wa, 0, sizeof(wa));
 
                for (i = 0; i < (int)RTE_DIM(internal_config.hugepage_info);

diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c b/lib/librte_eal/linuxapp/eal/eal_memory.c
index eb430a0..7cdd304 100644 (file)
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -1638,21 +1638,33 @@ eal_hugepage_init(void)
                        hp_sz_idx++) {
                for (socket_id = 0; socket_id < RTE_MAX_NUMA_NODES;
                                socket_id++) {
+                       struct rte_memseg **pages;
                        struct hugepage_info *hpi = &used_hp[hp_sz_idx];
                        unsigned int num_pages = hpi->num_pages[socket_id];
-                       int num_pages_alloc;
+                       int num_pages_alloc, i;
 
                        if (num_pages == 0)
                                continue;
 
+                       pages = malloc(sizeof(*pages) * num_pages);
+
                        RTE_LOG(DEBUG, EAL, "Allocating %u pages of size %" PRIu64 "M on socket %i\n",
                                num_pages, hpi->hugepage_sz >> 20, socket_id);
 
-                       num_pages_alloc = eal_memalloc_alloc_seg_bulk(NULL,
+                       num_pages_alloc = eal_memalloc_alloc_seg_bulk(pages,
                                        num_pages, hpi->hugepage_sz,
                                        socket_id, true);
-                       if (num_pages_alloc < 0)
+                       if (num_pages_alloc < 0) {
+                               free(pages);
                                return -1;
+                       }
+
+                       /* mark preallocated pages as unfreeable */
+                       for (i = 0; i < num_pages_alloc; i++) {
+                               struct rte_memseg *ms = pages[i];
+                               ms->flags |= RTE_MEMSEG_FLAG_DO_NOT_FREE;
+                       }
+                       free(pages);
                }
        }
        return 0;