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AJvYcCUhoOeRE/6sjIkOsTDOpdk6W9Lt3PkUHssriVn/Jhs/Wmz3YI8OaGwDzHrgAvf+wHM4ydc0GXZx/Q==@kvack.org X-Gm-Message-State: AOJu0YzCmEnWzbo3VPvmpCCefvcDTcIYuZTcRdKzHFgPlvUm8CXGpHIj lFYcuoTKJj4Le+eqoeEfZS26ATjHBTeb3egblrFrWpzRV9+wuRNP2X5H876OmpE8eX3GRlaYrk2 aKaeUH9b8ql3FGQU7Zp9cOpe5pcuumcQJeAYTUIxZ8w== X-Gm-Gg: ATEYQzw4O9FX41HKp7mjOOcOwl+WCvnZXjRfvbRQFjXQSnaL5OSuNXk3EWOHIxR7SNB p9diKYZR9lN/0rVLAphf+pW8KDb3IR598P1Um61GoDdEzfJ7FNL/D5Dq7Que9n3IdZPfKRq4yeW GicfT+hLI348i60EznNu9CyZYjJDutEQNQMLGkOMe+/YmifcNcls/jr1XJdNpUNr+vKEO9mYdlG aXaIBSzD4watyIaMIu3KkgykMn3TkxhObUdEuypMrwWMraqdFdoihfCy8DvO6u/wgxy9GWo3w2Z yaWMbZ5k8GvDWRskD/7vFNyw2KXqV8ubaYqwRQYiNQ== X-Received: by 2002:a05:690e:23c4:b0:64a:fe95:2ba7 with SMTP id 956f58d0204a3-64e62fa66bfmr100462d50.31.1773331964675; Thu, 12 Mar 2026 09:12:44 -0700 (PDT) MIME-Version: 1.0 References: <20260310031138.509730-1-r@hev.cc> <20260310031138.509730-2-r@hev.cc> <7937d789-539f-47db-838f-c153ca6cfc50@kernel.org> In-Reply-To: <7937d789-539f-47db-838f-c153ca6cfc50@kernel.org> From: hev Date: Fri, 13 Mar 2026 00:12:32 +0800 X-Gm-Features: AaiRm51siSCEAkZ-ba-2YedtaHq7E4-85jHPxVQW2_x0EqyQuvL291b70026mMs Message-ID: Subject: Re: [PATCH v4 1/2] huge_mm: add stubs for THP-disabled configs To: "David Hildenbrand (Arm)" Cc: Alexander Viro , Andrew Morton , Baolin Wang , Barry Song , Christian Brauner , Dev Jain , Jan Kara , Kees Cook , Lance Yang , "Liam R. Howlett" , Lorenzo Stoakes , Matthew Wilcox , Nico Pache , Ryan Roberts , Zi Yan , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C449E1C0015 X-Stat-Signature: mbm4gjhud6ne8aetm1ambwzfqki1wa85 X-Rspam-User: X-HE-Tag: 1773331965-860667 X-HE-Meta: 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 9Mg2kUCC VYO6jmLQpu4ZZBR7Ov7Z34/KaeQbRdzXcFZch6lKZH2H5EXox4jMZiX2Q5o/ijcHQQV1wItFMu8LbLRcobsgfPzszoyJLQxibLTZbu0rH1Awg9LUAgNcoDDMyQZaVihBGtL6iz7WkUHq3Z/GiBKcKx0La8zQRBfo8VMwe3Qse8ji8+Op6qfAp3q45yUonpl1FlAbRDx3036GOe1n/LVNN9qO1ZUWsnraYD0EuI5qdhJsuRF0ol/v4UaPL3d8EFXBZGkYaN+KRxDn6A2YI6UOrSCCXa8QFXGiF581rbVL+GeyvWYqdvxhkCIZZhKnGcALWKs3K9mMAbzxFP6hbXsDF5GObMmf47KB6SORHsS6JAJuvcxh6E+Nf9bEMguSRcZO5yGkA4sqKTCL4JwLt2TYGGcdAn26yJKsYYpey+FzMI5a0EYQDfMabOaFQCwGvWR9C2N2lnrR43OjV8V0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi David, On Thu, Mar 12, 2026 at 11:57=E2=80=AFPM David Hildenbrand (Arm) wrote: > > On 3/12/26 16:53, David Hildenbrand (Arm) wrote: > > On 3/10/26 04:11, WANG Rui wrote: > >> hugepage_global_enabled() and hugepage_global_always() only exist > >> when CONFIG_TRANSPARENT_HUGEPAGE is set. Add inline stubs that > >> return false to let code compile when THP is disabled. > >> > >> Signed-off-by: WANG Rui > >> --- > >> include/linux/huge_mm.h | 10 ++++++++++ > >> 1 file changed, 10 insertions(+) > >> > >> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > >> index a4d9f964dfde..badeebd4ea98 100644 > >> --- a/include/linux/huge_mm.h > >> +++ b/include/linux/huge_mm.h > >> @@ -570,6 +570,16 @@ void map_anon_folio_pmd_nopf(struct folio *folio,= pmd_t *pmd, > >> > >> #else /* CONFIG_TRANSPARENT_HUGEPAGE */ > >> > >> +static inline bool hugepage_global_enabled(void) > >> +{ > >> + return false; > >> +} > >> + > >> +static inline bool hugepage_global_always(void) > >> +{ > >> + return false; > >> +} > >> + > >> static inline bool folio_test_pmd_mappable(struct folio *folio) > >> { > >> return false; > > > > There are other ways to enable PMD THP. So I don't quite think this is > > the right tool for the job. > > Ah, you care about file THPs ... gah. > > Why can't we simply do the alignment without considering the current > setting? The main motivation of raising the alignment here is to increase the chance of getting PMD-sized THPs for executable mappings. If THP is not in "always" mode, the kernel will not automatically collapse file-backed mappings into THPs, so the increased alignment would not actually improve THP usage. In that case we would only be introducing additional padding in the virtual address layout, which slightly reduces ASLR entropy without providing a practical benefit. That's why the current code limits this to the "always" mode. Thanks, Rui