Re: [LTP] [PATCH] Fix short of nodemask array.

[Zhouping Liu <zliu@redhat.com>]

Hi Lans,

----- Original Message -----
> From: "gmail" <lans.zhang2008@gmail.com>
> To: ltp-list@lists.sourceforge.net
> Sent: Monday, March 4, 2013 12:49:45 PM
> Subject: [LTP] [PATCH]  Fix short of nodemask array.
> 
> In kernel, when the user specified more nodes, e.g, 512 nodes, than
> supported, e.g, 4 nodes, just check if the non supported part is all
> zero. If user space just specified the nodemask array with only one
> element, which makes the check in kernel actually become invalid.

I think the comments here is not clear, you should explain more details
about the 'one element' or the reason why the checking in kernel will
be invalid.

> In addition, some test cases in current implement doesn't consider
> if a node number is greater than sizeof(unsigned long) * 8 - 1.

yes, you are right, we don't care the system which has more than 512 numa nodes.
and the current code only support 64 numa nodes, only one unsigned long node mask.

I checked kernel code in RHEL6, CONFIG_NODES_SHIFT=9, so 512 is the biggest
value to support in RHEL6 for x86_64, and I didn't meet any large NUMA system
which have 512+ numa nodes so far.

> 
> Signed-off-by: Lans Zhang <lans.zhang2008@gmail.com>
> ---
>   testcases/kernel/mem/cpuset/cpuset01.c |    6 +++---
>   testcases/kernel/mem/ksm/ksm02.c       |    6 +++---
>   testcases/kernel/mem/ksm/ksm04.c       |    6 +++---
>   testcases/kernel/mem/lib/mem.c         |    6 +++---
>   4 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/testcases/kernel/mem/cpuset/cpuset01.c
> b/testcases/kernel/mem/cpuset/cpuset01.c
> index b473e45..e459306 100644
> --- a/testcases/kernel/mem/cpuset/cpuset01.c
> +++ b/testcases/kernel/mem/cpuset/cpuset01.c
> @@ -93,7 +93,7 @@ static void testcpuset(void)
>   {
>   	int lc;
>   	int child, i, status;
> -	unsigned long nmask = 0;
> +	unsigned long nmask[MAXNODES / (8*sizeof(unsigned long))] = { 0 };
>   	char mems[BUFSIZ], buf[BUFSIZ];
> 
>   	read_cpuset_files(CPATH, "cpus", buf);
> @@ -108,8 +108,8 @@ static void testcpuset(void)
>   		tst_brkm(TBROK | TERRNO, cleanup, "fork");
>   	case 0:
>   		for (i = 0; i < nnodes; i++)
> -			nmask += 1 << nodes[i];
> -		if (set_mempolicy(MPOL_BIND, &nmask, MAXNODES) == -1)
> +			nmask[i / (8*sizeof(unsigned long))] |= 1 << (i % (8*sizeof(unsigned
> long)));
> +		if (set_mempolicy(MPOL_BIND, nmask, MAXNODES) == -1)
>   			tst_brkm(TBROK | TERRNO, cleanup, "set_mempolicy");
>   		exit(mem_hog_cpuset(ncpus > 1 ? ncpus : 1));
>   	}
> diff --git a/testcases/kernel/mem/ksm/ksm02.c
> b/testcases/kernel/mem/ksm/ksm02.c
> index be9ff96..9d2d142 100644
> --- a/testcases/kernel/mem/ksm/ksm02.c
> +++ b/testcases/kernel/mem/ksm/ksm02.c
> @@ -87,7 +87,7 @@ int main(int argc, char *argv[])
>   	int lc;
>   	char *msg;
>   	int size = 128, num = 3, unit = 1;
> -	unsigned long nmask = 0;
> +	unsigned long nmask[MAXNODES / (8*sizeof(unsigned long))] = { 0 };
>   	unsigned int node;
> 
>   	msg = parse_opts(argc, argv, ksm_options, ksm_usage);
> @@ -95,7 +95,7 @@ int main(int argc, char *argv[])
>   		tst_brkm(TBROK, NULL, "OPTION PARSING ERROR - %s", msg);
> 
>   	node = get_a_numa_node(tst_exit);
> -	nmask = 1 << node;
> +	nmask[node / (8*sizeof(unsigned long))] = 1 << (node % (8*sizeof(unsigned
> long)));

I found '1 << (node % (8*sizeof(unsigned long)))' is used frequently, I suggest we
can create a macro, such as:
# define GET_NODE_MASK(nid) 1 << (nid % (8*sizeof(unsigned long)))

also please update the patch, as there's some updates before your patch in lib/mem.c,
which makes some conflict with the latest tree.

Thanks,
Zhouping

> 
>   	setup();
> 
> @@ -103,7 +103,7 @@ int main(int argc, char *argv[])
>   		Tst_count = 0;
>   		check_ksm_options(&size, &num, &unit);
> 
> -		if (set_mempolicy(MPOL_BIND, &nmask, MAXNODES) == -1) {
> +		if (set_mempolicy(MPOL_BIND, nmask, MAXNODES) == -1) {
>   			if (errno != ENOSYS)
>   				tst_brkm(TBROK | TERRNO, cleanup,
>   					 "set_mempolicy");
> diff --git a/testcases/kernel/mem/ksm/ksm04.c
> b/testcases/kernel/mem/ksm/ksm04.c
> index e4aa417..7829afd 100644
> --- a/testcases/kernel/mem/ksm/ksm04.c
> +++ b/testcases/kernel/mem/ksm/ksm04.c
> @@ -87,7 +87,7 @@ int main(int argc, char *argv[])
>   	int lc;
>   	char *msg;
>   	int size = 128, num = 3, unit = 1;
> -	unsigned long nmask = 0;
> +	unsigned long nmask[MAXNODES / (8*sizeof(unsigned long))] = { 0 };
>   	unsigned int node;
> 
>   	msg = parse_opts(argc, argv, ksm_options, ksm_usage);
> @@ -95,7 +95,7 @@ int main(int argc, char *argv[])
>   		tst_brkm(TBROK, NULL, "OPTION PARSING ERROR - %s", msg);
> 
>   	node = get_a_numa_node(tst_exit);
> -	nmask = 1 << node;
> +	nmask[node / (8*sizeof(unsigned long))] = 1 << (node % (8*sizeof(unsigned
> long)));
> 
>   	setup();
> 
> @@ -105,7 +105,7 @@ int main(int argc, char *argv[])
> 
>   		write_memcg();
> 
> -		if (set_mempolicy(MPOL_BIND, &nmask, MAXNODES) == -1) {
> +		if (set_mempolicy(MPOL_BIND, nmask, MAXNODES) == -1) {
>   			if (errno != ENOSYS)
>   				tst_brkm(TBROK | TERRNO, cleanup,
>   					 "set_mempolicy");
> diff --git a/testcases/kernel/mem/lib/mem.c b/testcases/kernel/mem/lib/mem.c
> index f095fe1..abe29fd 100644
> --- a/testcases/kernel/mem/lib/mem.c
> +++ b/testcases/kernel/mem/lib/mem.c
> @@ -66,12 +66,12 @@ void oom(int testcase, int mempolicy, int lite)
>   	int status;
>   #if HAVE_NUMA_H && HAVE_LINUX_MEMPOLICY_H && HAVE_NUMAIF_H \
>   	&& HAVE_MPOL_CONSTANTS
> -	unsigned long nmask = 0;
> +	unsigned long nmask[MAXNODES / (8*sizeof(unsigned long))] = { 0 };
>   	unsigned int node;
> 
>   	if (mempolicy)
>   		node = get_a_numa_node(cleanup);
> -	nmask += 1 << node;
> +	nmask[node / (8*sizeof(unsigned long))] = 1 << (node % (8*sizeof(unsigned
> long)));
>   #endif
> 
>   	switch (pid = fork()) {
> @@ -81,7 +81,7 @@ void oom(int testcase, int mempolicy, int lite)
>   #if HAVE_NUMA_H && HAVE_LINUX_MEMPOLICY_H && HAVE_NUMAIF_H \
>   	&& HAVE_MPOL_CONSTANTS
>   		if (mempolicy)
> -			if (set_mempolicy(MPOL_BIND, &nmask, MAXNODES) == -1)
> +			if (set_mempolicy(MPOL_BIND, nmask, MAXNODES) == -1)
>   				tst_brkm(TBROK | TERRNO, cleanup,
>   					 "set_mempolicy");
>   #endif
> --
> 1.7.8.110.g4cb5d
> 
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-- 
Thanks,
Zhouping

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