linux-kernel - Re: [PATCH] kselftest: fix OOM in memory compaction test

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Message-ID: <7f319aac-ef79-a7b0-372c-b52062063f97@kernel.org>
Date:   Tue, 9 Jan 2018 09:47:24 -0700
From:   Shuah Khan <shuah@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Sri Jayaramappa <sjayaram@...mai.com>, stable@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shuah Khan <shuahkh@....samsung.com>,
        Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH] kselftest: fix OOM in memory compaction test

On 01/09/2018 09:26 AM, Arnd Bergmann wrote:
> Running the compaction_test sometimes results in out-of-memory
> failures. When I debugged this, it turned out that the code to
> reset the number of hugepages to the initial value is simply
> broken since we write into an open sysctl file descriptor
> multiple times without seeking back to the start.
> 
> Adding the lseek here fixes the problem.
> 
> Cc: stable@...r.kernel.org
> Reported-by: Naresh Kamboju <naresh.kamboju@...aro.org>
> Link: https://bugs.linaro.org/show_bug.cgi?id=3145
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  tools/testing/selftests/vm/compaction_test.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/testing/selftests/vm/compaction_test.c b/tools/testing/selftests/vm/compaction_test.c
> index a65b016d4c13..1097f04e4d80 100644
> --- a/tools/testing/selftests/vm/compaction_test.c
> +++ b/tools/testing/selftests/vm/compaction_test.c
> @@ -137,6 +137,8 @@ int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
>  	printf("No of huge pages allocated = %d\n",
>  	       (atoi(nr_hugepages)));
>  
> +	lseek(fd, 0, SEEK_SET);
> +
>  	if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
>  	    != strlen(initial_nr_hugepages)) {
>  		perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
> 


Thanks for the patch. I will get this into 4.16-rc1

thanks,
-- Shuah