Re: [LTP] [PATCH] mmap_24-1: Change vm.max_map_count if needed

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> diff --git a/testcases/open_posix_testsuite/conformance/interfaces/mmap/24-1.c b/testcases/open_posix_testsuite/conformance/interfaces/mmap/24-1.c
> index 6cc8349e1..91677d289 100644
> --- a/testcases/open_posix_testsuite/conformance/interfaces/mmap/24-1.c
> +++ b/testcases/open_posix_testsuite/conformance/interfaces/mmap/24-1.c
> @@ -31,12 +31,40 @@
>  #include <stdint.h>
>  #include "posixtest.h"
>  
> +#define MAX_MAP_COUNT_PATH "/proc/sys/vm/max_map_count"
> +#define MAP_COUNT_LIMIT 65530
> +
> +void proc_write_val(const char *path, size_t val)
> +{
> +	FILE *procfile;
> +
> +	procfile = fopen(path, "r+");
> +
> +	if (!procfile)
> +		return;

We should print a message that we failed to open the file for the update
here, otherwise it's not clear if we managed to update the limit or not.

> +	fprintf(procfile, "%zu", val);
> +	fclose(procfile);
> +}
> +
>  int main(void)
>  {
>  	char tmpfname[256];
>  	void *pa;
> -	size_t len;
> +	size_t len, max_map_count = 0;
>  	int fd;
> +	FILE *procfile;
> +
> +	/* Change vm.max_map_count to avoid OOM */
> +	procfile = fopen(MAX_MAP_COUNT_PATH, "r+");
> +
> +	if (procfile) {
> +		fscanf(procfile, "%zu", &max_map_count);
> +		fclose(procfile);
> +	}
> +
> +	if (max_map_count > MAP_COUNT_LIMIT)
> +		proc_write_val(MAX_MAP_COUNT_PATH, MAP_COUNT_LIMIT);
>  
>  	/* Size of the shared memory object */
>  	size_t shm_size = 1024;
> @@ -78,5 +106,10 @@ int main(void)
>  
>  	close(fd);
>  	printf("Test FAILED: Did not get ENOMEM as expected\n");
> +
> +	/* Restore original vm.max_map_count */
> +	if (max_map_count > MAP_COUNT_LIMIT)
> +		proc_write_val(MAX_MAP_COUNT_PATH, max_map_count);


Otherwise it looks good:

Reviewed-by: Cyril Hrubis <chrubis@suse.cz>

-- 
Cyril Hrubis
chrubis@suse.cz

-- 
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