* [PATCH] unshare_test: set nr_open using soft limit
@ 2025-03-28 14:47 lufei
2025-03-31 18:32 ` Petr Vorel
0 siblings, 1 reply; 3+ messages in thread
From: lufei @ 2025-03-28 14:47 UTC (permalink / raw)
To: linux-kselftest; +Cc: pvorel, viro, lufei
Set maximum file descriptor number limit by rlimit.rlim_max than
nr_open(hard limit). Hard limit may cause dup2 fail.
Signed-off-by: lufei <lufei@uniontech.com>
---
tools/testing/selftests/core/unshare_test.c | 28 +++++++++++++--------
1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/core/unshare_test.c b/tools/testing/selftests/core/unshare_test.c
index 7fec9dfb1b0e..2c4e7104b0d9 100644
--- a/tools/testing/selftests/core/unshare_test.c
+++ b/tools/testing/selftests/core/unshare_test.c
@@ -26,10 +26,11 @@ TEST(unshare_EMFILE)
.exit_signal = SIGCHLD,
};
int fd;
- ssize_t n, n2;
- static char buf[512], buf2[512];
+ ssize_t n, n2, n3;
+ static char buf[512], buf2[512], buf3[512];
struct rlimit rlimit;
int nr_open;
+ int rlimit_max;
fd = open("/proc/sys/fs/nr_open", O_RDWR);
ASSERT_GE(fd, 0);
@@ -42,22 +43,24 @@ TEST(unshare_EMFILE)
ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit));
- /* bump fs.nr_open */
- n2 = sprintf(buf2, "%d\n", nr_open + 1024);
+ rlimit_max = rlimit.rlim_max;
+
+ /* bump rlimit.rlim_max */
+ n2 = sprintf(buf2, "%d\n", rlimit_max + 1024);
lseek(fd, 0, SEEK_SET);
write(fd, buf2, n2);
/* bump ulimit -n */
- rlimit.rlim_cur = nr_open + 1024;
- rlimit.rlim_max = nr_open + 1024;
+ rlimit.rlim_cur = rlimit_max + 1024;
+ rlimit.rlim_max = rlimit_max + 1024;
EXPECT_EQ(0, setrlimit(RLIMIT_NOFILE, &rlimit)) {
lseek(fd, 0, SEEK_SET);
write(fd, buf, n);
exit(EXIT_FAILURE);
}
- /* get a descriptor past the old fs.nr_open */
- EXPECT_GE(dup2(2, nr_open + 64), 0) {
+ /* get a descriptor past the old rlimit.rlim_max */
+ EXPECT_GE(dup2(2, rlimit_max + 64), 0) {
lseek(fd, 0, SEEK_SET);
write(fd, buf, n);
exit(EXIT_FAILURE);
@@ -74,15 +77,20 @@ TEST(unshare_EMFILE)
if (pid == 0) {
int err;
- /* restore fs.nr_open */
+ n3 = sprintf(buf3, "%d\n", rlimit_max);
lseek(fd, 0, SEEK_SET);
- write(fd, buf, n);
+ write(fd, buf3, n3);
+
/* ... and now unshare(CLONE_FILES) must fail with EMFILE */
err = unshare(CLONE_FILES);
EXPECT_EQ(err, -1)
exit(EXIT_FAILURE);
EXPECT_EQ(errno, EMFILE)
exit(EXIT_FAILURE);
+
+ /* restore fs.nr_open */
+ lseek(fd, 0, SEEK_SET);
+ write(fd, buf, n);
exit(EXIT_SUCCESS);
}
--
2.39.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] unshare_test: set nr_open using soft limit
2025-03-28 14:47 [PATCH] unshare_test: set nr_open using soft limit lufei
@ 2025-03-31 18:32 ` Petr Vorel
2025-04-01 1:43 ` Lu Fei
0 siblings, 1 reply; 3+ messages in thread
From: Petr Vorel @ 2025-03-31 18:32 UTC (permalink / raw)
To: lufei; +Cc: linux-kselftest, viro
Hi all,
> Set maximum file descriptor number limit by rlimit.rlim_max than
> nr_open(hard limit). Hard limit may cause dup2 fail.
It actually changes from failure:
# ./unshare_test
TAP version 13
1..1
# Starting 1 tests from 1 test cases.
# RUN global.unshare_EMFILE ...
# unshare_test.c:60:unshare_EMFILE:Expected dup2(2, nr_open + 64) (-1) >= 0 (0)
# unshare_EMFILE: Test failed
# FAIL global.unshare_EMFILE
not ok 1 global.unshare_EMFILE
# FAILED: 0 / 1 tests passed.
# Totals: pass:0 fail:1 xfail:0 xpass:0 skip:0 error:0
to pass:
TAP version 13
1..1
# Starting 1 tests from 1 test cases.
# RUN global.unshare_EMFILE ...
# OK global.unshare_EMFILE
ok 1 global.unshare_EMFILE
# PASSED: 1 / 1 tests passed.
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> Signed-off-by: lufei <lufei@uniontech.com>
> ---
> tools/testing/selftests/core/unshare_test.c | 28 +++++++++++++--------
> 1 file changed, 18 insertions(+), 10 deletions(-)
> diff --git a/tools/testing/selftests/core/unshare_test.c b/tools/testing/selftests/core/unshare_test.c
> index 7fec9dfb1b0e..2c4e7104b0d9 100644
> --- a/tools/testing/selftests/core/unshare_test.c
> +++ b/tools/testing/selftests/core/unshare_test.c
> @@ -26,10 +26,11 @@ TEST(unshare_EMFILE)
> .exit_signal = SIGCHLD,
> };
> int fd;
> - ssize_t n, n2;
> - static char buf[512], buf2[512];
> + ssize_t n, n2, n3;
> + static char buf[512], buf2[512], buf3[512];
> struct rlimit rlimit;
> int nr_open;
> + int rlimit_max;
> fd = open("/proc/sys/fs/nr_open", O_RDWR);
> ASSERT_GE(fd, 0);
> @@ -42,22 +43,24 @@ TEST(unshare_EMFILE)
> ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit));
> - /* bump fs.nr_open */
> - n2 = sprintf(buf2, "%d\n", nr_open + 1024);
> + rlimit_max = rlimit.rlim_max;
> +
> + /* bump rlimit.rlim_max */
> + n2 = sprintf(buf2, "%d\n", rlimit_max + 1024);
> lseek(fd, 0, SEEK_SET);
> write(fd, buf2, n2);
> /* bump ulimit -n */
> - rlimit.rlim_cur = nr_open + 1024;
> - rlimit.rlim_max = nr_open + 1024;
> + rlimit.rlim_cur = rlimit_max + 1024;
> + rlimit.rlim_max = rlimit_max + 1024;
> EXPECT_EQ(0, setrlimit(RLIMIT_NOFILE, &rlimit)) {
> lseek(fd, 0, SEEK_SET);
> write(fd, buf, n);
> exit(EXIT_FAILURE);
> }
> - /* get a descriptor past the old fs.nr_open */
> - EXPECT_GE(dup2(2, nr_open + 64), 0) {
> + /* get a descriptor past the old rlimit.rlim_max */
> + EXPECT_GE(dup2(2, rlimit_max + 64), 0) {
> lseek(fd, 0, SEEK_SET);
> write(fd, buf, n);
> exit(EXIT_FAILURE);
> @@ -74,15 +77,20 @@ TEST(unshare_EMFILE)
> if (pid == 0) {
> int err;
> - /* restore fs.nr_open */
> + n3 = sprintf(buf3, "%d\n", rlimit_max);
> lseek(fd, 0, SEEK_SET);
> - write(fd, buf, n);
> + write(fd, buf3, n3);
nit: do we really need buf3? Can't we reuse buf2?
Or do I miss something obvious?
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Kind regards,
Petr
> +
> /* ... and now unshare(CLONE_FILES) must fail with EMFILE */
> err = unshare(CLONE_FILES);
> EXPECT_EQ(err, -1)
> exit(EXIT_FAILURE);
> EXPECT_EQ(errno, EMFILE)
> exit(EXIT_FAILURE);
> +
> + /* restore fs.nr_open */
> + lseek(fd, 0, SEEK_SET);
> + write(fd, buf, n);
> exit(EXIT_SUCCESS);
> }
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] unshare_test: set nr_open using soft limit
2025-03-31 18:32 ` Petr Vorel
@ 2025-04-01 1:43 ` Lu Fei
0 siblings, 0 replies; 3+ messages in thread
From: Lu Fei @ 2025-04-01 1:43 UTC (permalink / raw)
To: Petr Vorel; +Cc: linux-kselftest, viro
Hi Petr,
Thanks very much for reply.
On Mon, Mar 31, 2025 at 08:32:27PM +0200, Petr Vorel wrote:
> Hi all,
>
> > Set maximum file descriptor number limit by rlimit.rlim_max than
> > nr_open(hard limit). Hard limit may cause dup2 fail.
>
> It actually changes from failure:
>
> # ./unshare_test
> TAP version 13
> 1..1
> # Starting 1 tests from 1 test cases.
> # RUN global.unshare_EMFILE ...
> # unshare_test.c:60:unshare_EMFILE:Expected dup2(2, nr_open + 64) (-1) >= 0 (0)
> # unshare_EMFILE: Test failed
> # FAIL global.unshare_EMFILE
> not ok 1 global.unshare_EMFILE
> # FAILED: 0 / 1 tests passed.
> # Totals: pass:0 fail:1 xfail:0 xpass:0 skip:0 error:0
>
> to pass:
>
> TAP version 13
> 1..1
> # Starting 1 tests from 1 test cases.
> # RUN global.unshare_EMFILE ...
> # OK global.unshare_EMFILE
> ok 1 global.unshare_EMFILE
> # PASSED: 1 / 1 tests passed.
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> > Signed-off-by: lufei <lufei@uniontech.com>
> > ---
> > tools/testing/selftests/core/unshare_test.c | 28 +++++++++++++--------
> > 1 file changed, 18 insertions(+), 10 deletions(-)
>
> > diff --git a/tools/testing/selftests/core/unshare_test.c b/tools/testing/selftests/core/unshare_test.c
> > index 7fec9dfb1b0e..2c4e7104b0d9 100644
> > --- a/tools/testing/selftests/core/unshare_test.c
> > +++ b/tools/testing/selftests/core/unshare_test.c
> > @@ -26,10 +26,11 @@ TEST(unshare_EMFILE)
> > .exit_signal = SIGCHLD,
> > };
> > int fd;
> > - ssize_t n, n2;
> > - static char buf[512], buf2[512];
> > + ssize_t n, n2, n3;
> > + static char buf[512], buf2[512], buf3[512];
> > struct rlimit rlimit;
> > int nr_open;
> > + int rlimit_max;
>
> > fd = open("/proc/sys/fs/nr_open", O_RDWR);
> > ASSERT_GE(fd, 0);
> > @@ -42,22 +43,24 @@ TEST(unshare_EMFILE)
>
> > ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit));
>
> > - /* bump fs.nr_open */
> > - n2 = sprintf(buf2, "%d\n", nr_open + 1024);
> > + rlimit_max = rlimit.rlim_max;
> > +
> > + /* bump rlimit.rlim_max */
> > + n2 = sprintf(buf2, "%d\n", rlimit_max + 1024);
> > lseek(fd, 0, SEEK_SET);
> > write(fd, buf2, n2);
>
> > /* bump ulimit -n */
> > - rlimit.rlim_cur = nr_open + 1024;
> > - rlimit.rlim_max = nr_open + 1024;
> > + rlimit.rlim_cur = rlimit_max + 1024;
> > + rlimit.rlim_max = rlimit_max + 1024;
> > EXPECT_EQ(0, setrlimit(RLIMIT_NOFILE, &rlimit)) {
> > lseek(fd, 0, SEEK_SET);
> > write(fd, buf, n);
> > exit(EXIT_FAILURE);
> > }
>
> > - /* get a descriptor past the old fs.nr_open */
> > - EXPECT_GE(dup2(2, nr_open + 64), 0) {
> > + /* get a descriptor past the old rlimit.rlim_max */
> > + EXPECT_GE(dup2(2, rlimit_max + 64), 0) {
> > lseek(fd, 0, SEEK_SET);
> > write(fd, buf, n);
> > exit(EXIT_FAILURE);
> > @@ -74,15 +77,20 @@ TEST(unshare_EMFILE)
> > if (pid == 0) {
> > int err;
>
> > - /* restore fs.nr_open */
> > + n3 = sprintf(buf3, "%d\n", rlimit_max);
> > lseek(fd, 0, SEEK_SET);
> > - write(fd, buf, n);
> > + write(fd, buf3, n3);
> nit: do we really need buf3? Can't we reuse buf2?
> Or do I miss something obvious?
>
Reuse buf2 is better. I'll make change.
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
>
> Kind regards,
> Petr
>
> > +
> > /* ... and now unshare(CLONE_FILES) must fail with EMFILE */
> > err = unshare(CLONE_FILES);
> > EXPECT_EQ(err, -1)
> > exit(EXIT_FAILURE);
> > EXPECT_EQ(errno, EMFILE)
> > exit(EXIT_FAILURE);
> > +
> > + /* restore fs.nr_open */
> > + lseek(fd, 0, SEEK_SET);
> > + write(fd, buf, n);
> > exit(EXIT_SUCCESS);
> > }
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-03-28 14:47 [PATCH] unshare_test: set nr_open using soft limit lufei
2025-03-31 18:32 ` Petr Vorel
2025-04-01 1:43 ` Lu Fei
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