Re: [PATCH v3 01/10] selftests/mm: Report errno when things fail in gup_longterm

[David Hildenbrand]

  
  		/*

 * TODO: if the kernel ever supports long-term R/W pinning on
@@ -202,7 +204,8 @@ static void do_test(int fd, size_t size, enum test_type 
type, bool shared)
/* Skip on errors, as we might just lack kernel support. */
ret = io_uring_queue_init(1, &ring, 0);
if (ret < 0) {
-   ksft_test_result_skip("io_uring_queue_init() failed\n");
+   ksft_test_result_skip("io_uring_queue_init() failed 
(%s)\n",
+ strerror(errno));


This function is documented to return -errno. I'm not sure if errno is 
guaranteed to be left unmodified (not clearly documented in the man 
page). So you might just want to use strerror(-ret) here.


Same applies to the other io_uring functions.

--
Cheers,

David / dhildenb

Re: [PATCH v3 01/10] selftests/mm: Report errno when things fail in gup_longterm

[Dev Jain]

On 28/02/25 10:24 pm, Brendan Jackman wrote:

Just reporting failure doesn't tell you what went wrong. This can fail
in different ways so report errno to help the reader get started
debugging.

Signed-off-by: Brendan Jackman 


Reviewed-by: Dev Jain 

[PATCH v3 01/10] selftests/mm: Report errno when things fail in gup_longterm

[Brendan Jackman]

Just reporting failure doesn't tell you what went wrong. This can fail
in different ways so report errno to help the reader get started
debugging.

Signed-off-by: Brendan Jackman 
---
 tools/testing/selftests/mm/gup_longterm.c | 37 ++-
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/mm/gup_longterm.c 
b/tools/testing/selftests/mm/gup_longterm.c
index 
9423ad439a6140163bdef2974615bb86406a8c14..879e9e4e8cce8127656fabe098abf7db5f6c5e23
 100644
--- a/tools/testing/selftests/mm/gup_longterm.c
+++ b/tools/testing/selftests/mm/gup_longterm.c
@@ -96,13 +96,13 @@ static void do_test(int fd, size_t size, enum test_type 
type, bool shared)
int ret;
 
if (ftruncate(fd, size)) {
-   ksft_test_result_fail("ftruncate() failed\n");
+   ksft_test_result_fail("ftruncate() failed (%s)\n", 
strerror(errno));
return;
}
 
if (fallocate(fd, 0, 0, size)) {
if (size == pagesize)
-   ksft_test_result_fail("fallocate() failed\n");
+   ksft_test_result_fail("fallocate() failed (%s)\n", 
strerror(errno));
else
ksft_test_result_skip("need more free huge pages\n");
return;
@@ -112,7 +112,7 @@ static void do_test(int fd, size_t size, enum test_type 
type, bool shared)
   shared ? MAP_SHARED : MAP_PRIVATE, fd, 0);
if (mem == MAP_FAILED) {
if (size == pagesize || shared)
-   ksft_test_result_fail("mmap() failed\n");
+   ksft_test_result_fail("mmap() failed (%s)\n", 
strerror(errno));
else
ksft_test_result_skip("need more free huge pages\n");
return;
@@ -130,7 +130,7 @@ static void do_test(int fd, size_t size, enum test_type 
type, bool shared)
 */
ret = mprotect(mem, size, PROT_READ);
if (ret) {
-   ksft_test_result_fail("mprotect() failed\n");
+   ksft_test_result_fail("mprotect() failed (%s)\n", 
strerror(errno));
goto munmap;
}
/* FALLTHROUGH */
@@ -165,18 +165,20 @@ static void do_test(int fd, size_t size, enum test_type 
type, bool shared)
args.flags |= rw ? PIN_LONGTERM_TEST_FLAG_USE_WRITE : 0;
ret = ioctl(gup_fd, PIN_LONGTERM_TEST_START, &args);
if (ret && errno == EINVAL) {
-   ksft_test_result_skip("PIN_LONGTERM_TEST_START 
failed\n");
+   ksft_test_result_skip("PIN_LONGTERM_TEST_START failed 
(EINVAL)n");
break;
} else if (ret && errno == EFAULT) {
ksft_test_result(!should_work, "Should have failed\n");
break;
} else if (ret) {
-   ksft_test_result_fail("PIN_LONGTERM_TEST_START 
failed\n");
+   ksft_test_result_fail("PIN_LONGTERM_TEST_START failed 
(%s)\n",
+ strerror(errno));
break;
}
 
if (ioctl(gup_fd, PIN_LONGTERM_TEST_STOP))
-   ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP 
failed\n");
+   ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed 
(%s)\n",
+  strerror(errno));
 
/*
 * TODO: if the kernel ever supports long-term R/W pinning on
@@ -202,7 +204,8 @@ static void do_test(int fd, size_t size, enum test_type 
type, bool shared)
/* Skip on errors, as we might just lack kernel support. */
ret = io_uring_queue_init(1, &ring, 0);
if (ret < 0) {
-   ksft_test_result_skip("io_uring_queue_init() failed\n");
+   ksft_test_result_skip("io_uring_queue_init() failed 
(%s)\n",
+ strerror(errno));
break;
}
/*
@@ -215,13 +218,15 @@ static void do_test(int fd, size_t size, enum test_type 
type, bool shared)
/* Only new kernels return EFAULT. */
if (ret && (errno == ENOSPC || errno == EOPNOTSUPP ||
errno == EFAULT)) {
-   ksft_test_result(!should_work, "Should have failed\n");
+   ksft_test_result(!should_work, "Should have failed 
(%s)\n",
+strerror(errno));
} else if (ret) {
/*
 * We might just lack support or have insufficient
 * MEMLOCK limits.
 */
-   ksft_test_result_skip("io_uring_register_buffers() 
failed\n");
+