[v5] eal: use madvise to exclude unmapped memory from being dumped
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Commit Message
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
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
>
>
> --
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> that is not related to the business is not authorized or permitted by
> SmartX.
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>
@@ -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;
}
@@ -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 */