[PATCH v2 1/1] lib: Retry safe_clone() on ENOSPC|EUSERS

[PATCH v2 1/1] lib: Retry safe_clone() on ENOSPC|EUSERS

[Petr Vorel]

In some tests we are creating the namespaces faster than they are being
asynchronously cleaned up in the kernel:

$ sudo ./userns08 -i 10
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:36: TBROK: clone3 failed: ENOSPC (28)

Thus retrying the clone() on ENOSPC (or EUSERS for kernel < 4.9).

Suggested-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
changes v1->v2:
* use TST_RETRY_FN_EXP_BACKOFF() (Cyril)

NOTE: 0.1s seems to be safe, although using TST_RETRY_FUNC() with 1s
(the default) would be of course OK.

Kind regards,
Petr

 lib/tst_test.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/tst_test.c b/lib/tst_test.c
index 384c73e163..2e89d954ec 100644
--- a/lib/tst_test.c
+++ b/lib/tst_test.c
@@ -436,6 +436,9 @@ pid_t safe_fork(const char *filename, unsigned int lineno)
 	return pid;
 }
 
+/* too fast creating namespaces => retrying */
+#define TST_CHECK_ENOSPC(x) ((x) >= 0 || !(errno == ENOSPC || errno == EUSERS))
+
 pid_t safe_clone(const char *file, const int lineno,
 		 const struct tst_clone_args *args)
 {
@@ -444,7 +447,7 @@ pid_t safe_clone(const char *file, const int lineno,
 	if (!tst_test->forks_child)
 		tst_brk(TBROK, "test.forks_child must be set!");
 
-	pid = tst_clone(args);
+	pid = TST_RETRY_FN_EXP_BACKOFF(tst_clone(args), TST_CHECK_ENOSPC, 0.1);
 
 	switch (pid) {
 	case -1:
-- 
2.35.1

Re: [PATCH v2 1/1] lib: Retry safe_clone() on ENOSPC|EUSERS

[Petr Vorel]

Oops, wrong list, sorry.

Kind regards,
Petr

> In some tests we are creating the namespaces faster than they are being
> asynchronously cleaned up in the kernel:

> $ sudo ./userns08 -i 10
> userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
> userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
> userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
> userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
> userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
> userns08.c:36: TBROK: clone3 failed: ENOSPC (28)

> Thus retrying the clone() on ENOSPC (or EUSERS for kernel < 4.9).

> Suggested-by: Cyril Hrubis <chrubis@suse.cz>
> Signed-off-by: Petr Vorel <pvorel@suse.cz>
> ---
> changes v1->v2:
> * use TST_RETRY_FN_EXP_BACKOFF() (Cyril)

> NOTE: 0.1s seems to be safe, although using TST_RETRY_FUNC() with 1s
> (the default) would be of course OK.

> Kind regards,
> Petr

>  lib/tst_test.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

> diff --git a/lib/tst_test.c b/lib/tst_test.c
> index 384c73e163..2e89d954ec 100644
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -436,6 +436,9 @@ pid_t safe_fork(const char *filename, unsigned int lineno)
>  	return pid;
>  }

> +/* too fast creating namespaces => retrying */
> +#define TST_CHECK_ENOSPC(x) ((x) >= 0 || !(errno == ENOSPC || errno == EUSERS))
> +
>  pid_t safe_clone(const char *file, const int lineno,
>  		 const struct tst_clone_args *args)
>  {
> @@ -444,7 +447,7 @@ pid_t safe_clone(const char *file, const int lineno,
>  	if (!tst_test->forks_child)
>  		tst_brk(TBROK, "test.forks_child must be set!");

> -	pid = tst_clone(args);
> +	pid = TST_RETRY_FN_EXP_BACKOFF(tst_clone(args), TST_CHECK_ENOSPC, 0.1);

>  	switch (pid) {
>  	case -1: