diff mbox series

[v2] eal: use madvise to exclude unmapped memory from being dumped

Message ID 20200424105016.28974-1-fengli@smartx.com (mailing list archive)
State Superseded, archived
Delegated to: David Marchand
Headers
Series [v2] eal: use madvise to exclude unmapped memory from being dumped |

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Commit Message

Li Feng April 24, 2020, 10:50 a.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>
---
V2:
- 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 | 26 ++++++++++++++++++++++++++
 lib/librte_eal/linux/eal_memalloc.c       |  6 ++++++
 2 files changed, 32 insertions(+)

Comments

Anatoly Burakov April 24, 2020, 11:23 a.m. UTC | #1 
On 24-Apr-20 11:50 AM, 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>
> ---
> V2:
> - add support for freebsd.
> - when free_seg is called, mark the memory MADV_DONTDUMP.
> - when alloc_seg is called, mark the memory MADV_DODUMP.

Isn't this v3 now?

> 
>   lib/librte_eal/common/eal_common_memory.c | 26 ++++++++++++++++++++++++++
>   lib/librte_eal/linux/eal_memalloc.c       |  6 ++++++
>   2 files changed, 32 insertions(+)
> 
> diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
> index cc7d54e0c..83be94a20 100644
> --- a/lib/librte_eal/common/eal_common_memory.c
> +++ b/lib/librte_eal/common/eal_common_memory.c
> @@ -177,6 +177,32 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
>   		after_len = RTE_PTR_DIFF(map_end, aligned_end);
>   		if (after_len > 0)
>   			munmap(aligned_end, after_len);
> +
> +		/*
> +		 * Exclude this pages from a core dump.
> +		 */
> +#ifdef RTE_EXEC_ENV_LINUX
> +		if (madvise(aligned_addr, *size, MADV_DONTDUMP) != 0)
> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> +				strerror(errno));
> +#elif RTE_EXEC_ENV_FREEBSD
> +		if (madvise(aligned_addr, *size, MADV_NOCORE) != 0)
> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> +				strerror(errno));
> +#endif
> +	} else {
> +		/*
> +		 * Exclude this pages from a core dump.
> +		 */
> +#ifdef RTE_EXEC_ENV_LINUX
> +		if (madvise(mapped_addr, map_sz, MADV_DONTDUMP) != 0)
> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> +				strerror(errno));
> +#elif RTE_EXEC_ENV_FREEBSD
> +		if (madvise(mapped_addr, map_sz, MADV_NOCORE) != 0)
> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> +				strerror(errno));
> +#endif
>   	}

DRY (Don't Repeat Yourself) :) Probably easier to do "if (!unmap) ..." 
than putting this into two places.

>   
>   	return aligned_addr;
> diff --git a/lib/librte_eal/linux/eal_memalloc.c b/lib/librte_eal/linux/eal_memalloc.c
> index af6d0d023..9d2a6fc6f 100644
> --- a/lib/librte_eal/linux/eal_memalloc.c
> +++ b/lib/librte_eal/linux/eal_memalloc.c
> @@ -571,6 +571,9 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
>   		goto resized;
>   	}
>   
> +	if (madvise(addr, alloc_sz, MADV_DODUMP) != 0)
> +		RTE_LOG(DEBUG, EAL, "madvise failed: %s\n", strerror(errno));
> +

See discussion for v2, i believe this is unnecessary.

>   	/* In linux, hugetlb limitations, like cgroup, are
>   	 * enforced at fault time instead of mmap(), even
>   	 * with the option of MAP_POPULATE. Kernel will send
> @@ -687,6 +690,9 @@ 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 */
>
Bruce Richardson April 24, 2020, 11:36 a.m. UTC | #2 
On Fri, Apr 24, 2020 at 12:23:44PM +0100, Burakov, Anatoly wrote:
> On 24-Apr-20 11:50 AM, 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>
> > ---
> > V2:
> > - add support for freebsd.
> > - when free_seg is called, mark the memory MADV_DONTDUMP.
> > - when alloc_seg is called, mark the memory MADV_DODUMP.
> 
> Isn't this v3 now?
> 
> > 
> >   lib/librte_eal/common/eal_common_memory.c | 26 ++++++++++++++++++++++++++
> >   lib/librte_eal/linux/eal_memalloc.c       |  6 ++++++
> >   2 files changed, 32 insertions(+)
> > 
> > diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
> > index cc7d54e0c..83be94a20 100644
> > --- a/lib/librte_eal/common/eal_common_memory.c
> > +++ b/lib/librte_eal/common/eal_common_memory.c
> > @@ -177,6 +177,32 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
> >   		after_len = RTE_PTR_DIFF(map_end, aligned_end);
> >   		if (after_len > 0)
> >   			munmap(aligned_end, after_len);
> > +
> > +		/*
> > +		 * Exclude this pages from a core dump.
> > +		 */
> > +#ifdef RTE_EXEC_ENV_LINUX
> > +		if (madvise(aligned_addr, *size, MADV_DONTDUMP) != 0)
> > +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +				strerror(errno));
> > +#elif RTE_EXEC_ENV_FREEBSD
> > +		if (madvise(aligned_addr, *size, MADV_NOCORE) != 0)
> > +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +				strerror(errno));
> > +#endif
> > +	} else {
> > +		/*
> > +		 * Exclude this pages from a core dump.
> > +		 */
> > +#ifdef RTE_EXEC_ENV_LINUX
> > +		if (madvise(mapped_addr, map_sz, MADV_DONTDUMP) != 0)
> > +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +				strerror(errno));
> > +#elif RTE_EXEC_ENV_FREEBSD
> > +		if (madvise(mapped_addr, map_sz, MADV_NOCORE) != 0)
> > +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +				strerror(errno));
> > +#endif
> >   	}
> 
> DRY (Don't Repeat Yourself) :) Probably easier to do "if (!unmap) ..." than
> putting this into two places.
> 
Can I also suggest putting this at the top of the file:
#ifdef RTE_EXEC_ENV_LINUX
#define RTE_DONTDUMP MADV_DONTDUMP
#elif RTE_EXEC_ENV_FREEBSD
#define RTE_DONTDUMP MADV_NOCORE
#else
#error ....
#endif

and thereafter using RTE_DONTDUMP flag and avoiding any #ifdefs inline in
the code.
Anatoly Burakov April 24, 2020, 11:46 a.m. UTC | #3 
On 24-Apr-20 12:36 PM, Bruce Richardson wrote:
> On Fri, Apr 24, 2020 at 12:23:44PM +0100, Burakov, Anatoly wrote:
>> On 24-Apr-20 11:50 AM, 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>
>>> ---
>>> V2:
>>> - add support for freebsd.
>>> - when free_seg is called, mark the memory MADV_DONTDUMP.
>>> - when alloc_seg is called, mark the memory MADV_DODUMP.
>>
>> Isn't this v3 now?
>>
>>>
>>>    lib/librte_eal/common/eal_common_memory.c | 26 ++++++++++++++++++++++++++
>>>    lib/librte_eal/linux/eal_memalloc.c       |  6 ++++++
>>>    2 files changed, 32 insertions(+)
>>>
>>> diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
>>> index cc7d54e0c..83be94a20 100644
>>> --- a/lib/librte_eal/common/eal_common_memory.c
>>> +++ b/lib/librte_eal/common/eal_common_memory.c
>>> @@ -177,6 +177,32 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
>>>    		after_len = RTE_PTR_DIFF(map_end, aligned_end);
>>>    		if (after_len > 0)
>>>    			munmap(aligned_end, after_len);
>>> +
>>> +		/*
>>> +		 * Exclude this pages from a core dump.
>>> +		 */
>>> +#ifdef RTE_EXEC_ENV_LINUX
>>> +		if (madvise(aligned_addr, *size, MADV_DONTDUMP) != 0)
>>> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
>>> +				strerror(errno));
>>> +#elif RTE_EXEC_ENV_FREEBSD
>>> +		if (madvise(aligned_addr, *size, MADV_NOCORE) != 0)
>>> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
>>> +				strerror(errno));
>>> +#endif
>>> +	} else {
>>> +		/*
>>> +		 * Exclude this pages from a core dump.
>>> +		 */
>>> +#ifdef RTE_EXEC_ENV_LINUX
>>> +		if (madvise(mapped_addr, map_sz, MADV_DONTDUMP) != 0)
>>> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
>>> +				strerror(errno));
>>> +#elif RTE_EXEC_ENV_FREEBSD
>>> +		if (madvise(mapped_addr, map_sz, MADV_NOCORE) != 0)
>>> +			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
>>> +				strerror(errno));
>>> +#endif
>>>    	}
>>
>> DRY (Don't Repeat Yourself) :) Probably easier to do "if (!unmap) ..." than
>> putting this into two places.
>>
> Can I also suggest putting this at the top of the file:
> #ifdef RTE_EXEC_ENV_LINUX
> #define RTE_DONTDUMP MADV_DONTDUMP
> #elif RTE_EXEC_ENV_FREEBSD
> #define RTE_DONTDUMP MADV_NOCORE
> #else
> #error ....
> #endif
> 
> and thereafter using RTE_DONTDUMP flag and avoiding any #ifdefs inline in
> the code.
> 
+1
Li Feng April 24, 2020, 12:37 p.m. UTC | #4 
Thanks,

Feng Li

Burakov, Anatoly <anatoly.burakov@intel.com> 于2020年4月24日周五 下午7:23写道：
>
> On 24-Apr-20 11:50 AM, 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>
> > ---
> > V2:
> > - add support for freebsd.
> > - when free_seg is called, mark the memory MADV_DONTDUMP.
> > - when alloc_seg is called, mark the memory MADV_DODUMP.
>
> Isn't this v3 now?
My mistake. I will using v4 for next version.
>
> >
> >   lib/librte_eal/common/eal_common_memory.c | 26 ++++++++++++++++++++++++++
> >   lib/librte_eal/linux/eal_memalloc.c       |  6 ++++++
> >   2 files changed, 32 insertions(+)
> >
> > diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
> > index cc7d54e0c..83be94a20 100644
> > --- a/lib/librte_eal/common/eal_common_memory.c
> > +++ b/lib/librte_eal/common/eal_common_memory.c
> > @@ -177,6 +177,32 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
> >               after_len = RTE_PTR_DIFF(map_end, aligned_end);
> >               if (after_len > 0)
> >                       munmap(aligned_end, after_len);
> > +
> > +             /*
> > +              * Exclude this pages from a core dump.
> > +              */
> > +#ifdef RTE_EXEC_ENV_LINUX
> > +             if (madvise(aligned_addr, *size, MADV_DONTDUMP) != 0)
> > +                     RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +                             strerror(errno));
> > +#elif RTE_EXEC_ENV_FREEBSD
> > +             if (madvise(aligned_addr, *size, MADV_NOCORE) != 0)
> > +                     RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +                             strerror(errno));
> > +#endif
> > +     } else {
> > +             /*
> > +              * Exclude this pages from a core dump.
> > +              */
> > +#ifdef RTE_EXEC_ENV_LINUX
> > +             if (madvise(mapped_addr, map_sz, MADV_DONTDUMP) != 0)
> > +                     RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +                             strerror(errno));
> > +#elif RTE_EXEC_ENV_FREEBSD
> > +             if (madvise(mapped_addr, map_sz, MADV_NOCORE) != 0)
> > +                     RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
> > +                             strerror(errno));
> > +#endif
> >       }
>
> DRY (Don't Repeat Yourself) :) Probably easier to do "if (!unmap) ..."
> than putting this into two places.

OK. I put this into two places, because the size is more accurate in this place.

>
> >
> >       return aligned_addr;
> > diff --git a/lib/librte_eal/linux/eal_memalloc.c b/lib/librte_eal/linux/eal_memalloc.c
> > index af6d0d023..9d2a6fc6f 100644
> > --- a/lib/librte_eal/linux/eal_memalloc.c
> > +++ b/lib/librte_eal/linux/eal_memalloc.c
> > @@ -571,6 +571,9 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
> >               goto resized;
> >       }
> >
> > +     if (madvise(addr, alloc_sz, MADV_DODUMP) != 0)
> > +             RTE_LOG(DEBUG, EAL, "madvise failed: %s\n", strerror(errno));
> > +
>
> See discussion for v2, i believe this is unnecessary.
>
> >       /* In linux, hugetlb limitations, like cgroup, are
> >        * enforced at fault time instead of mmap(), even
> >        * with the option of MAP_POPULATE. Kernel will send
> > @@ -687,6 +690,9 @@ 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 */
> >
>
>
> --
> Thanks,
> Anatoly
diff mbox series

Patch

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index cc7d54e0c..83be94a20 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -177,6 +177,32 @@  eal_get_virtual_area(void *requested_addr, size_t *size,
 		after_len = RTE_PTR_DIFF(map_end, aligned_end);
 		if (after_len > 0)
 			munmap(aligned_end, after_len);
+
+		/*
+		 * Exclude this pages from a core dump.
+		 */
+#ifdef RTE_EXEC_ENV_LINUX
+		if (madvise(aligned_addr, *size, MADV_DONTDUMP) != 0)
+			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
+				strerror(errno));
+#elif RTE_EXEC_ENV_FREEBSD
+		if (madvise(aligned_addr, *size, MADV_NOCORE) != 0)
+			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
+				strerror(errno));
+#endif
+	} else {
+		/*
+		 * Exclude this pages from a core dump.
+		 */
+#ifdef RTE_EXEC_ENV_LINUX
+		if (madvise(mapped_addr, map_sz, MADV_DONTDUMP) != 0)
+			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
+				strerror(errno));
+#elif RTE_EXEC_ENV_FREEBSD
+		if (madvise(mapped_addr, map_sz, MADV_NOCORE) != 0)
+			RTE_LOG(DEBUG, EAL, "madvise failed: %s\n",
+				strerror(errno));
+#endif
 	}
 
 	return aligned_addr;
diff --git a/lib/librte_eal/linux/eal_memalloc.c b/lib/librte_eal/linux/eal_memalloc.c
index af6d0d023..9d2a6fc6f 100644
--- a/lib/librte_eal/linux/eal_memalloc.c
+++ b/lib/librte_eal/linux/eal_memalloc.c
@@ -571,6 +571,9 @@  alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 		goto resized;
 	}
 
+	if (madvise(addr, alloc_sz, MADV_DODUMP) != 0)
+		RTE_LOG(DEBUG, EAL, "madvise failed: %s\n", strerror(errno));
+
 	/* In linux, hugetlb limitations, like cgroup, are
 	 * enforced at fault time instead of mmap(), even
 	 * with the option of MAP_POPULATE. Kernel will send
@@ -687,6 +690,9 @@  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 */