[dpdk-dev] [PATCH] mem: mark pages as not accessed when reserving VA

[dpdk-dev] [PATCH] mem: mark pages as not accessed when reserving VA

[David Marchand]

When the memory allocator reserves virtual addresses, it still does not
know what they will be used for.
Besides, huge areas are reserved for memory hotplug in multiprocess
setups. But most of the pages are unused in the whole life of the
processes.

Change protection mode to PROT_NONE when only reserving VA.
The memory allocator already switches to the right mode when making use
of it.

It also has the nice effect of getting those pages skipped by the kernel
when calling mlockall() or when a coredump gets generated.

Cc: stable@dpdk.org

Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>
---
 lib/librte_eal/common/eal_common_memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index 4a9cc1f19..cc7d54e0c 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -97,7 +97,7 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
 			return NULL;
 		}
 
-		mapped_addr = mmap(requested_addr, (size_t)map_sz, PROT_READ,
+		mapped_addr = mmap(requested_addr, (size_t)map_sz, PROT_NONE,
 				mmap_flags, -1, 0);
 		if (mapped_addr == MAP_FAILED && allow_shrink)
 			*size -= page_sz;
-- 
2.23.0

Re: [dpdk-dev] [PATCH] mem: mark pages as not accessed when reserving VA

[Maxime Coquelin]

On 3/9/20 3:54 PM, David Marchand wrote:
> When the memory allocator reserves virtual addresses, it still does not
> know what they will be used for.
> Besides, huge areas are reserved for memory hotplug in multiprocess
> setups. But most of the pages are unused in the whole life of the
> processes.
> 
> Change protection mode to PROT_NONE when only reserving VA.
> The memory allocator already switches to the right mode when making use
> of it.
> 
> It also has the nice effect of getting those pages skipped by the kernel
> when calling mlockall() or when a coredump gets generated.
> 
> Cc: stable@dpdk.org
> 
> Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---
>  lib/librte_eal/common/eal_common_memory.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
> index 4a9cc1f19..cc7d54e0c 100644
> --- a/lib/librte_eal/common/eal_common_memory.c
> +++ b/lib/librte_eal/common/eal_common_memory.c
> @@ -97,7 +97,7 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
>  			return NULL;
>  		}
>  
> -		mapped_addr = mmap(requested_addr, (size_t)map_sz, PROT_READ,
> +		mapped_addr = mmap(requested_addr, (size_t)map_sz, PROT_NONE,
>  				mmap_flags, -1, 0);
>  		if (mapped_addr == MAP_FAILED && allow_shrink)
>  			*size -= page_sz;
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks!
Maxime

Re: [dpdk-dev] [PATCH] mem: mark pages as not accessed when reserving VA

[Aaron Conole]

David Marchand <david.marchand@redhat.com> writes:

> When the memory allocator reserves virtual addresses, it still does not
> know what they will be used for.
> Besides, huge areas are reserved for memory hotplug in multiprocess
> setups. But most of the pages are unused in the whole life of the
> processes.
>
> Change protection mode to PROT_NONE when only reserving VA.
> The memory allocator already switches to the right mode when making use
> of it.
>
> It also has the nice effect of getting those pages skipped by the kernel
> when calling mlockall() or when a coredump gets generated.
>
> Cc: stable@dpdk.org
>
> Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---

Acked-by: Aaron Conole <aconole@redhat.com>

Thanks!

Re: [dpdk-dev] [PATCH] mem: mark pages as not accessed when reserving VA

[Burakov, Anatoly]

On 09-Mar-20 2:54 PM, David Marchand wrote:
> When the memory allocator reserves virtual addresses, it still does not
> know what they will be used for.
> Besides, huge areas are reserved for memory hotplug in multiprocess
> setups. But most of the pages are unused in the whole life of the
> processes.
> 
> Change protection mode to PROT_NONE when only reserving VA.
> The memory allocator already switches to the right mode when making use
> of it.
> 
> It also has the nice effect of getting those pages skipped by the kernel
> when calling mlockall() or when a coredump gets generated.
> 
> Cc: stable@dpdk.org
> 
> Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: David Marchand <david.marchand@redhat.com>
> ---

Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>

-- 
Thanks,
Anatoly

Re: [dpdk-dev] [dpdk-stable] [PATCH] mem: mark pages as not accessed when reserving VA

[David Marchand]

On Mon, Mar 9, 2020 at 3:55 PM David Marchand <david.marchand@redhat.com> wrote:
>
> When the memory allocator reserves virtual addresses, it still does not
> know what they will be used for.
> Besides, huge areas are reserved for memory hotplug in multiprocess
> setups. But most of the pages are unused in the whole life of the
> processes.
>
> Change protection mode to PROT_NONE when only reserving VA.
> The memory allocator already switches to the right mode when making use
> of it.
>
> It also has the nice effect of getting those pages skipped by the kernel
> when calling mlockall() or when a coredump gets generated.
>
> Cc: stable@dpdk.org
>
> Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: David Marchand <david.marchand@redhat.com>

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Aaron Conole <aconole@redhat.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>


Applied.

-- 
David Marchand