mem: exclude unused memory from core dump

Currently, even though memory is mapped with PROT_NONE, this does not
cause it to be excluded from core dumps. This is counter-productive,
because in a lot of cases, this memory will go unused (e.g. when the
memory subsystem preallocates VA space but hasn't yet mapped physical
pages into it).

Use `madvise()` call with MADV_DONTDUMP/MADV_NOCORE to exclude the
unused memory from being dumped.

Signed-off-by: Li Feng <fengli@smartx.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index cc7d54e..9a797a4 100644 (file)
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -40,6 +40,14 @@
 static void *next_baseaddr;
 static uint64_t system_page_sz;
 
+#ifdef RTE_EXEC_ENV_LINUX
+#define RTE_DONTDUMP MADV_DONTDUMP
+#elif RTE_EXEC_ENV_FREEBSD
+#define RTE_DONTDUMP MADV_NOCORE
+#else
+#error "madvise doesn't support this OS"
+#endif
+
 #define MAX_MMAP_WITH_DEFINED_ADDR_TRIES 5
 void *
 eal_get_virtual_area(void *requested_addr, size_t *size,
@@ -179,6 +187,13 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
                        munmap(aligned_end, after_len);
        }
 
+       if (!unmap) {
+               /* Exclude these pages from a core dump. */
+               if (madvise(aligned_addr, *size, RTE_DONTDUMP) != 0)
+                       RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
+                               strerror(errno));
+       }
+
        return aligned_addr;
 }
 

diff --git a/lib/librte_eal/linux/eal_memalloc.c b/lib/librte_eal/linux/eal_memalloc.c
index 678094a..2c717f8 100644 (file)
--- a/lib/librte_eal/linux/eal_memalloc.c
+++ b/lib/librte_eal/linux/eal_memalloc.c
@@ -687,6 +687,9 @@ free_seg(struct rte_memseg *ms, struct hugepage_info *hi,
                return -1;
        }
 
+       if (madvise(ms->addr, ms->len, MADV_DONTDUMP) != 0)
+               RTE_LOG(DEBUG, EAL, "madvise failed: %s\n", strerror(errno));
+
        exit_early = false;
 
        /* if we're using anonymous hugepages, nothing to be done */