[LTP] [PATCH v2 1/3] lib: add functions to adjust oom score

[LTP] [PATCH v2 1/3] lib: add functions to adjust oom score

[Li Wang]

This introduces function to LTP for adjusting the oom_score_adj of
target process, which may be helpful in OOM tests to prevent kernel
killing the main or lib process during test running.

The exported global tst_enable_oom_protection function can be used
at anywhere you want to protect, but please remember that if you
do enable protection on a process($PID) that all the children will
inherit its score and be ignored by OOM Killer as well. So that's
why tst_cancel_oom_protection is recommended to combination in use.

Signed-off-by: Li Wang <liwang@redhat.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
---

Notes:
    Changes v1->v2:
        * Move commit messages to source code comment
        * correct typos

 include/tst_memutils.h | 19 +++++++++++++++++++
 lib/tst_memutils.c     | 29 +++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/include/tst_memutils.h b/include/tst_memutils.h
index f605f544e..dc18df6d2 100644
--- a/include/tst_memutils.h
+++ b/include/tst_memutils.h
@@ -25,4 +25,23 @@ void tst_pollute_memory(size_t maxsize, int fillchar);
  */
 long long tst_available_mem(void);
 
+/*
+ * Enable OOM protection to prevent process($PID) being killed by OOM Killer.
+ *   echo -1000 >/proc/$PID/oom_score_adj
+ *
+ * Note:
+ *  This exported tst_enable_oom_protection function can be used at anywhere
+ *  you want to protect, but please remember that if you do enable protection
+ *  on a process($PID) that all the children will inherit its score and be
+ *  ignored by OOM Killer as well. So that's why tst_cancel_oom_protection is
+ *  recommended to combination in use.
+ */
+void tst_enable_oom_protection(pid_t pid);
+
+/*
+ * Cancel the OOM protection for the process($PID).
+ *   echo 0 >/proc/$PID/oom_score_adj
+ */
+void tst_cancel_oom_protection(pid_t pid);
+
 #endif /* TST_MEMUTILS_H__ */
diff --git a/lib/tst_memutils.c b/lib/tst_memutils.c
index bd09cf6fa..d97b35007 100644
--- a/lib/tst_memutils.c
+++ b/lib/tst_memutils.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2020 SUSE LLC <mdoucha@suse.cz>
  */
 
+#include <stdio.h>
 #include <unistd.h>
 #include <limits.h>
 #include <sys/sysinfo.h>
@@ -91,3 +92,31 @@ long long tst_available_mem(void)
 
 	return mem_available;
 }
+
+static void set_oom_score_adj(pid_t pid, int value)
+{
+	int val;
+	char score_path[64];
+
+	if (access("/proc/self/oom_score_adj", F_OK) == -1) {
+		tst_res(TINFO, "Warning: oom_score_adj does not exist");
+		return;
+	}
+
+	sprintf(score_path, "/proc/%d/oom_score_adj", pid);
+	SAFE_FILE_PRINTF(score_path, "%d", value);
+
+	SAFE_FILE_SCANF(score_path, "%d", &val);
+	if (val != value)
+		tst_brk(TBROK, "oom_score_adj = %d, but expect %d.", val, value);
+}
+
+void tst_enable_oom_protection(pid_t pid)
+{
+	set_oom_score_adj(pid, -1000);
+}
+
+void tst_cancel_oom_protection(pid_t pid)
+{
+	set_oom_score_adj(pid, 0);
+}
-- 
2.31.1


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[LTP] [PATCH v2 2/3] lib: enable OOM protection for the main process

[Li Wang]

Here invoke OOM protection in fork_testrun, since it is the key point
to distiguish many process branches. We do protect main ($PID) process
from killing by OOM Killer, hope this can help to get the completed
correct report for all of LTP tests.

Fundamental principle:

                   ltp test harness --> library process
  (oom protection)   main --> tst_run_tcases --> ... --> fork_testrun
  (cancel protection)  testrun --> run_tests --> ... --> testname
                         child_test --> ... --> end

Signed-off-by: Li Wang <liwang@redhat.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
---

Notes:
    Changes v1->v2:
        * remove the protection for parent process as suggested by Martin

 lib/tst_test.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/tst_test.c b/lib/tst_test.c
index ce2b8239d..0b370e691 100644
--- a/lib/tst_test.c
+++ b/lib/tst_test.c
@@ -1441,11 +1441,14 @@ static int fork_testrun(void)
 
 	SAFE_SIGNAL(SIGINT, sigint_handler);
 
+	tst_enable_oom_protection(getpid());
+
 	test_pid = fork();
 	if (test_pid < 0)
 		tst_brk(TBROK | TERRNO, "fork()");
 
 	if (!test_pid) {
+		tst_cancel_oom_protection(getpid());
 		SAFE_SIGNAL(SIGALRM, SIG_DFL);
 		SAFE_SIGNAL(SIGUSR1, SIG_DFL);
 		SAFE_SIGNAL(SIGINT, SIG_DFL);
-- 
2.31.1


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Re: [LTP] [PATCH v2 2/3] lib: enable OOM protection for the main process

[Cyril Hrubis]

Hi!
> Here invoke OOM protection in fork_testrun, since it is the key point
> to distiguish many process branches. We do protect main ($PID) process
> from killing by OOM Killer, hope this can help to get the completed
> correct report for all of LTP tests.
> 
> Fundamental principle:
> 
>                    ltp test harness --> library process
>   (oom protection)   main --> tst_run_tcases --> ... --> fork_testrun
>   (cancel protection)  testrun --> run_tests --> ... --> testname
>                          child_test --> ... --> end
> 
> Signed-off-by: Li Wang <liwang@redhat.com>
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> ---
> 
> Notes:
>     Changes v1->v2:
>         * remove the protection for parent process as suggested by Martin
> 
>  lib/tst_test.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/lib/tst_test.c b/lib/tst_test.c
> index ce2b8239d..0b370e691 100644
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -1441,11 +1441,14 @@ static int fork_testrun(void)
>  
>  	SAFE_SIGNAL(SIGINT, sigint_handler);
>  
> +	tst_enable_oom_protection(getpid());
> +
>  	test_pid = fork();
>  	if (test_pid < 0)
>  		tst_brk(TBROK | TERRNO, "fork()");
>  
>  	if (!test_pid) {
> +		tst_cancel_oom_protection(getpid());
>  		SAFE_SIGNAL(SIGALRM, SIG_DFL);
>  		SAFE_SIGNAL(SIGUSR1, SIG_DFL);
>  		SAFE_SIGNAL(SIGINT, SIG_DFL);

The fork_testrun() function is called in a loop, it would be a bit
cleaner to put the tst_enable_protection() call to the tst_run_tcases()
instead since we don't have to enable it over and over.

-- 
Cyril Hrubis
chrubis@suse.cz

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[LTP] [PATCH v2 3/3] oom: enable OOM protection for mem lib process

[Li Wang]

Just simply invoke oom protection on mem library to make
it can collect full state of children.

Signed-off-by: Li Wang <liwang@redhat.com>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
---
 testcases/kernel/mem/lib/mem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/testcases/kernel/mem/lib/mem.c b/testcases/kernel/mem/lib/mem.c
index ac890491c..566e29055 100644
--- a/testcases/kernel/mem/lib/mem.c
+++ b/testcases/kernel/mem/lib/mem.c
@@ -129,8 +129,11 @@ void oom(int testcase, int lite, int retcode, int allow_sigkill)
 	pid_t pid;
 	int status, threads;
 
+	tst_enable_oom_protection(getpid());
+
 	switch (pid = SAFE_FORK()) {
 	case 0:
+		tst_cancel_oom_protection(getpid());
 		threads = MAX(1, tst_ncpus() - 1);
 		child_alloc(testcase, lite, threads);
 	default:
-- 
2.31.1


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Re: [LTP] [PATCH v2 3/3] oom: enable OOM protection for mem lib process

[Cyril Hrubis]

Hi!
> Just simply invoke oom protection on mem library to make
> it can collect full state of children.
> 
> Signed-off-by: Li Wang <liwang@redhat.com>
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> ---
>  testcases/kernel/mem/lib/mem.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/testcases/kernel/mem/lib/mem.c b/testcases/kernel/mem/lib/mem.c
> index ac890491c..566e29055 100644
> --- a/testcases/kernel/mem/lib/mem.c
> +++ b/testcases/kernel/mem/lib/mem.c
> @@ -129,8 +129,11 @@ void oom(int testcase, int lite, int retcode, int allow_sigkill)
>  	pid_t pid;
>  	int status, threads;
>  
> +	tst_enable_oom_protection(getpid());
> +
>  	switch (pid = SAFE_FORK()) {
>  	case 0:
> +		tst_cancel_oom_protection(getpid());
>  		threads = MAX(1, tst_ncpus() - 1);
>  		child_alloc(testcase, lite, threads);
>  	default:

Looking at the code we have, we always pass getpid(). We may as well
change the library to use /proc/self/oom_score_adj if 0 is passed
instead of the pid.

-- 
Cyril Hrubis
chrubis@suse.cz

-- 
Mailing list info: https://lists.linux.it/listinfo/ltp

Re: [LTP] [PATCH v2 3/3] oom: enable OOM protection for mem lib process

[Li Wang]

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On Fri, Dec 17, 2021 at 10:49 PM Cyril Hrubis <chrubis@suse.cz> wrote:


>
> > +     tst_enable_oom_protection(getpid());
> > +
> >       switch (pid = SAFE_FORK()) {
> >       case 0:
> > +             tst_cancel_oom_protection(getpid());
> >               threads = MAX(1, tst_ncpus() - 1);
> >               child_alloc(testcase, lite, threads);
> >       default:
>
> Looking at the code we have, we always pass getpid(). We may as well
> change the library to use /proc/self/oom_score_adj if 0 is passed
> instead of the pid.
>

Yes, agree with all suggestions (include comments in 1/3 2/3).

-- 
Regards,
Li Wang

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[-- Attachment #2: Type: text/plain, Size: 60 bytes --]


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Re: [LTP] [PATCH v2 1/3] lib: add functions to adjust oom score

[Cyril Hrubis]

Hi!
> +/*
> + * Enable OOM protection to prevent process($PID) being killed by OOM Killer.
> + *   echo -1000 >/proc/$PID/oom_score_adj
> + *
> + * Note:
> + *  This exported tst_enable_oom_protection function can be used at anywhere
> + *  you want to protect, but please remember that if you do enable protection
> + *  on a process($PID) that all the children will inherit its score and be
> + *  ignored by OOM Killer as well. So that's why tst_cancel_oom_protection is
> + *  recommended to combination in use.
> + */
> +void tst_enable_oom_protection(pid_t pid);
> +
> +/*
> + * Cancel the OOM protection for the process($PID).
> + *   echo 0 >/proc/$PID/oom_score_adj
> + */
> +void tst_cancel_oom_protection(pid_t pid);

Minor nit: opposite of enable is disable not cancel.

>  #endif /* TST_MEMUTILS_H__ */
> diff --git a/lib/tst_memutils.c b/lib/tst_memutils.c
> index bd09cf6fa..d97b35007 100644
> --- a/lib/tst_memutils.c
> +++ b/lib/tst_memutils.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2020 SUSE LLC <mdoucha@suse.cz>
>   */
>  
> +#include <stdio.h>
>  #include <unistd.h>
>  #include <limits.h>
>  #include <sys/sysinfo.h>
> @@ -91,3 +92,31 @@ long long tst_available_mem(void)
>  
>  	return mem_available;
>  }
> +
> +static void set_oom_score_adj(pid_t pid, int value)
> +{
> +	int val;
> +	char score_path[64];
> +
> +	if (access("/proc/self/oom_score_adj", F_OK) == -1) {
> +		tst_res(TINFO, "Warning: oom_score_adj does not exist");
> +		return;
> +	}
> +
> +	sprintf(score_path, "/proc/%d/oom_score_adj", pid);
> +	SAFE_FILE_PRINTF(score_path, "%d", value);
> +
> +	SAFE_FILE_SCANF(score_path, "%d", &val);
> +	if (val != value)
> +		tst_brk(TBROK, "oom_score_adj = %d, but expect %d.", val, value);
> +}
> +
> +void tst_enable_oom_protection(pid_t pid)
> +{
> +	set_oom_score_adj(pid, -1000);
> +}
> +
> +void tst_cancel_oom_protection(pid_t pid)
> +{
> +	set_oom_score_adj(pid, 0);
> +}
> -- 
> 2.31.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz

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