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

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Message-ID: <9be602c1-d627-6302-be1c-66c8068c7ecf@redhat.com>
Date:   Wed, 9 Aug 2023 09:40:30 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Ayush Jain <ayush.jain3@....com>, jglisse@...hat.com,
        akpm@...ux-foundation.org, shuah@...nel.org
Cc:     linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, bharata@....com,
        kalpana.shetty@....com, santosh.shukla@....com,
        Raghavendra K T <raghavendra.kt@....com>
Subject: Re: [PATCH] selftests/mm: FOLL_LONGTERM need to be updated to 0x100

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@....com>
> Reviewed-by: Raghavendra K T <raghavendra.kt@....com>
> ---
>   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@...hat.com>

-- 
Cheers,

David / dhildenb