[LTP] [PATCH] max_map_count: Fails due to negative memfree value

[LTP] [PATCH] max_map_count: Fails due to negative memfree value

[madhura]

In situations when memory is occupied to a certain higher limit by system processes, the amount of memory available may be in negative/low values not suitable for testing.
Hence its better to have a memory check prior to the test beginning.

Signed-off-by: Madhura P S <madhura@linux.vnet.ibm.com>

--- ltp-full-20130109/testcases/kernel/mem/tunable/max_map_count.c.org	2013-01-17 17:15:38.957032558 +0530
+++ ltp-full-20130109/testcases/kernel/mem/tunable/max_map_count.c	2013-01-17 17:16:58.092909326 +0530
@@ -152,7 +152,7 @@ static void max_map_count_test(void)
  	pid_t pid;
  	long max_maps;
  	long map_count;
-	long max_iters;
+	long max_iters = 0;
  	long memfree;
  
  	/*
@@ -174,7 +174,8 @@ static void max_map_count_test(void)
  	 */
  	memfree = read_meminfo("CommitLimit:") - read_meminfo("Committed_AS:");
  	/* 64 used as a bias to make sure no overflow happen */
-	max_iters = memfree / sysconf(_SC_PAGESIZE) * 1024 - 64;
+	if (memfree > 0)
+		max_iters = memfree / sysconf(_SC_PAGESIZE) * 1024 - 64;
  	if (max_iters > MAX_MAP_COUNT)
  		max_iters = MAX_MAP_COUNT;




-- 
With Regards,
Madhura P S


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Re: [LTP] [PATCH] max_map_count: Fails due to negative memfree value

[Zhouping Liu]

----- Original Message -----
> From: "madhura" <madhura@linux.vnet.ibm.com>
> To: ltp-list@lists.sourceforge.net
> Sent: Thursday, January 17, 2013 7:48:49 PM
> Subject: [LTP]  [PATCH] max_map_count: Fails due to negative memfree value
> 
> In situations when memory is occupied to a certain higher limit by
> system processes, the amount of memory available may be in
> negative/low values not suitable for testing.
> Hence its better to have a memory check prior to the test beginning.
> 
> Signed-off-by: Madhura P S <madhura@linux.vnet.ibm.com>
> 
> ---
> ltp-full-20130109/testcases/kernel/mem/tunable/max_map_count.c.org
> 	2013-01-17 17:15:38.957032558 +0530
> +++ ltp-full-20130109/testcases/kernel/mem/tunable/max_map_count.c
> 	2013-01-17 17:16:58.092909326 +0530
> @@ -152,7 +152,7 @@ static void max_map_count_test(void)
>   	pid_t pid;
>   	long max_maps;
>   	long map_count;
> -	long max_iters;
> +	long max_iters = 0;
>   	long memfree;
>   
>   	/*
> @@ -174,7 +174,8 @@ static void max_map_count_test(void)
>   	 */
>   	memfree = read_meminfo("CommitLimit:") -
>   	read_meminfo("Committed_AS:");
>   	/* 64 used as a bias to make sure no overflow happen */
> -	max_iters = memfree / sysconf(_SC_PAGESIZE) * 1024 - 64;
> +	if (memfree > 0)
> +		max_iters = memfree / sysconf(_SC_PAGESIZE) * 1024 - 64;

Generally, the situation (CommitLimit < Committed_AS) can't be hit,
IMO, if yes, that means your system has been some broken(I suppose it's kernel's issue)

so you should here add the below lines to catch the exception:

        else {
               tst_resm(TINFO, "CommmitLimit is %ld, Committed_AS"
                        " is %ld", commit_limit, committed);
               tst_brkm(TBROK, cleanup, "Unexpected error: "
                        "CommitLimit < Committed_AS");
        }

-- 
Thanks,
Zhouping

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