Re: [PATCH] selftests/mm: FOLL_LONGTERM need to be updated to 0x100

From: David Hildenbrand
Date: Wed Aug 09 2023 - 03:41:27 EST


On 08.08.23 14:43, Ayush Jain wrote:
After commit 2c2241081f7d ("mm/gup: move private gup FOLL_ flags to internal.h")
FOLL_LONGTERM flag value got updated from 0x10000 to 0x100 at
include/linux/mm_types.h.
As hmm.hmm_device_private.hmm_gup_test uses FOLL_LONGTERM
Updating same here as well.

Before this change test goes in an infinite assert loop in
hmm.hmm_device_private.hmm_gup_test
==========================================================
RUN hmm.hmm_device_private.hmm_gup_test ...
hmm-tests.c:1962:hmm_gup_test:Expected HMM_DMIRROR_PROT_WRITE..
..(2) == m[2] (34)
hmm-tests.c:157:hmm_gup_test:Expected ret (-1) == 0 (0)
hmm-tests.c:157:hmm_gup_test:Expected ret (-1) == 0 (0)
...
==========================================================

Call Trace:
<TASK>
? sched_clock+0xd/0x20
? __lock_acquire.constprop.0+0x120/0x6c0
? ktime_get+0x2c/0xd0
? sched_clock+0xd/0x20
? local_clock+0x12/0xd0
? lock_release+0x26e/0x3b0
pin_user_pages_fast+0x4c/0x70
gup_test_ioctl+0x4ff/0xbb0
? gup_test_ioctl+0x68c/0xbb0
__x64_sys_ioctl+0x99/0xd0
do_syscall_64+0x60/0x90
? syscall_exit_to_user_mode+0x2a/0x50
? do_syscall_64+0x6d/0x90
? syscall_exit_to_user_mode+0x2a/0x50
? do_syscall_64+0x6d/0x90
? irqentry_exit_to_user_mode+0xd/0x20
? irqentry_exit+0x3f/0x50
? exc_page_fault+0x96/0x200
entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f6aaa31aaff

After this change test is able to pass successfully.

Signed-off-by: Ayush Jain <ayush.jain3@xxxxxxx>
Reviewed-by: Raghavendra K T <raghavendra.kt@xxxxxxx>
---
tools/testing/selftests/mm/hmm-tests.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
index 4adaad1b822f..20294553a5dd 100644
--- a/tools/testing/selftests/mm/hmm-tests.c
+++ b/tools/testing/selftests/mm/hmm-tests.c
@@ -57,9 +57,14 @@ enum {
#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
/* Just the flags we need, copied from mm.h: */
+
+#ifndef FOLL_WRITE
#define FOLL_WRITE 0x01 /* check pte is writable */
-#define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite */
+#endif
+#ifndef FOLL_LONGTERM
+#define FOLL_LONGTERM 0x100 /* mapping lifetime is indefinite */
+#endif
FIXTURE(hmm)
{
int fd;

Kind of suboptimal that we are passing in FOLL_ flags. mm/gup_test.c should just have provided an abstraction for that.

Acked-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers,

David / dhildenb