[v5] eal: use madvise to exclude unmapped memory from being dumped

Message ID 20200424125311.25364-1-fengli@smartx.com (mailing list archive)
State Superseded, archived
Delegated to: David Marchand
Headers
Series [v5] eal: use madvise to exclude unmapped memory from being dumped |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-nxp-Performance success Performance Testing PASS
ci/iol-mellanox-Performance success Performance Testing PASS
ci/travis-robot warning Travis build: failed
ci/iol-testing fail Testing issues
ci/Intel-compilation fail apply issues

Commit Message

Li Feng April 24, 2020, 12:53 p.m. UTC
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 parameter to exclude the
unmapped memory from being dumped.

Signed-off-by: Li Feng <fengli@smartx.com>
---
v5:
- fix a code style.

V4:
- simplify the code;
- remove the undo code in V3;

V3:
- add support for freebsd.
- when free_seg is called, mark the memory MADV_DONTDUMP.
- when alloc_seg is called, mark the memory MADV_DODUMP.

 lib/librte_eal/common/eal_common_memory.c | 17 +++++++++++++++++
 lib/librte_eal/linux/eal_memalloc.c       |  3 +++
 2 files changed, 20 insertions(+)
  

Comments

Bruce Richardson April 24, 2020, 1:02 p.m. UTC | #1
On Fri, Apr 24, 2020 at 08:53:11PM +0800, Li Feng wrote:
> 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 parameter to exclude the
> unmapped memory from being dumped.
> 
> Signed-off-by: Li Feng <fengli@smartx.com>
> ---
> v5:
> - fix a code style.
> 
> V4:
> - simplify the code;
> - remove the undo code in V3;
> 
> V3:
> - add support for freebsd.
> - when free_seg is called, mark the memory MADV_DONTDUMP.
> - when alloc_seg is called, mark the memory MADV_DODUMP.
> 
>  lib/librte_eal/common/eal_common_memory.c | 17 +++++++++++++++++
>  lib/librte_eal/linux/eal_memalloc.c       |  3 +++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
> index cc7d54e0c..161e49825 100644
> --- 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
> +

You forgot to use RTE_DONTDUMP in place of MADV_DONTDUMP below.

>  #define MAX_MMAP_WITH_DEFINED_ADDR_TRIES 5
>  void *
>  eal_get_virtual_area(void *requested_addr, size_t *size,
> @@ -179,6 +187,15 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
>  			munmap(aligned_end, after_len);
>  	}
>  
> +	if (!unmap) {
> +		/*
> +		 * Exclude this pages from a core dump.
> +		 */
> +		if (madvise(aligned_addr, *size, MADV_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 af6d0d023..f628e0991 100644
> --- 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 */
> -- 
> 2.11.0
> 
> 
> -- 
> The SmartX email address is only for business purpose. Any sent message 
> that is not related to the business is not authorized or permitted by 
> SmartX.
> 本邮箱为北京志凌海纳科技有限公司(SmartX)工作邮箱. 如本邮箱发出的邮件与工作无关,该邮件未得到本公司任何的明示或默示的授权.
> 
>
  

Patch

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index cc7d54e0c..161e49825 100644
--- 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 +187,15 @@  eal_get_virtual_area(void *requested_addr, size_t *size,
 			munmap(aligned_end, after_len);
 	}
 
+	if (!unmap) {
+		/*
+		 * Exclude this pages from a core dump.
+		 */
+		if (madvise(aligned_addr, *size, MADV_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 af6d0d023..f628e0991 100644
--- 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 */