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Tue, 24 Jun 2025 06:26:40 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHB++0lFTLwZ/uIk8rBEB0BBiiS6oB3ZZcMHttMMaAQRA6oRGfpEoNz6CBPLYmL2Iv0nln+BzUAN1KxqAb6mdU= X-Received: by 2002:a17:90b:57e7:b0:311:ffe8:20e9 with SMTP id 98e67ed59e1d1-3159d8c5337mr29147770a91.17.1750771600470; Tue, 24 Jun 2025 06:26:40 -0700 (PDT) MIME-Version: 1.0 References: <20250621004808.368878-1-liwang@redhat.com> <20250624032748.393836-1-liwang@redhat.com> <4b69c14f-1001-48a0-9c83-6d2284b5a04a@redhat.com> In-Reply-To: <4b69c14f-1001-48a0-9c83-6d2284b5a04a@redhat.com> From: Li Wang Date: Tue, 24 Jun 2025 21:26:28 +0800 X-Gm-Features: Ac12FXy1PZJe5Ze5GMdmSt_1RC6z_ZvRWIazH3Pf6KOdGmj8grD0u2i4fh_nz9c Message-ID: Subject: Re: [PATCH v2] ksm_tests: Skip hugepage test when Transparent Hugepages are disabled To: David Hildenbrand Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Aruna Ramakrishna , Bagas Sanjaya , Catalin Marinas , Dave Hansen , Joey Gouly , Johannes Weiner , Keith Lucas , Ryan Roberts , Shuah Khan X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: Q1DvRYDRNRwQ9rhozmxUjAp07jrSwL9a_8PEov40YXw_1750771601 X-Mimecast-Originator: redhat.com Content-Type: multipart/alternative; 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charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi David, On Tue, Jun 24, 2025 at 4:25=E2=80=AFPM David Hildenbrand wrote: > On 24.06.25 05:27, Li Wang wrote: > > Some systems (e.g. minimal or real-time kernels) may not enable > > Transparent Hugepages (THP), causing MADV_HUGEPAGE to return EINVAL. > > This patch introduces a runtime check using the existing THP sysfs > > interface and skips the hugepage merging test (`-H`) when THP is > > not available. > > > > To avoid those failures: > > But we deliberately have in tools/testing/selftests/mm/config: > > CONFIG_TRANSPARENT_HUGEPAGE=3Dy > > So isn't this rather a test setup issue? Meaning, the environment is > not well prepared. > It's true that CONFIG_TRANSPARENT_HUGEPAGE=3Dy is explicitly enabled in tools/testing/selftests/mm/config, so ideally the runtime environment should also support THP. However, in practice, we've found that on some systems: - THP is disabled at boot time (transparent_hugepage=3Dnever) - Or manually disabled via sysfs - Or unavailable in RT kernels, containers, or minimal CI environments In these cases, the test will fail with EINVAL on madvise(MADV_HUGEPAGE), even though the kernel config is correct. To make the test suite more robust and avoid false negatives, this patch adds a runtime check for /sys/kernel/mm/transparent_hugepage/enabled. If THP is not available, the hugepage test (-H) is skipped with a clear message. --=20 Regards, Li Wang --0000000000005458120638514735 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi=C2=A0David,

On Tue, Jun 24, 202= 5 at 4:25=E2=80=AFPM David Hildenbrand <david@redhat.com> wrote:
On 24.06.25 05:27, Li Wang wrote:
> Some systems (e.g. minimal or real-time kernels) may not enable
> Transparent Hugepages (THP), causing MADV_HUGEPAGE to return EINVAL. > This patch introduces a runtime check using the existing THP sysfs
> interface and skips the hugepage merging test (`-H`) when THP is
> not available.
>
> To avoid those failures:

But we deliberately have in tools/testing/selftests/mm/config:

CONFIG_TRANSPARENT_HUGEPAGE=3Dy

So isn't this rather a test setup issue? Meaning, the environment is not well prepared.

It's true that CONFIG_TRANSPARENT_HUGEPAGE= =3Dy=C2=A0is= explicitly
enabled=C2=A0in tools= /testing/selftests/mm/config, so ideally the= =C2=A0runtime
= environment should also support THP.

However, in practice, we've found that on some syst= ems:

-=C2= =A0THP is disabled at boot time (transparent_hugepage=3Dnever)
-=C2=A0Or man= ually disabled via sysfs
-=C2=A0Or unavailable in RT kernels, containers, or minima= l CI environments

In these cases, the test will fail with EINVAL on = madvise(MADV_HUGEPAGE),
even though the kernel config is correct.

To make the test suite = more robust and avoid false negatives, this patch
adds a runtime check for /sys/kernel/mm/transp= arent_hugepage/enabled.

If THP is not= available, the hugepage test (-H) is skipped with a clear message.


--
Regards,
Li Wang
--0000000000005458120638514735--