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Sun, 07 Dec 2025 04:24:44 -0800 (PST) Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.200.81.1.6\)) Subject: Re: [PATCH v1 4/4] mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather From: Nadav Amit In-Reply-To: <0914A8DB-447C-4E62-B151-62E5E4E99749@gmail.com> Date: Sun, 7 Dec 2025 14:24:32 +0200 Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Arnd Bergmann , Muchun Song , Oscar Salvador , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pedro Falcato , Rik van Riel , Harry Yoo , Laurence Oberman , Prakash Sangappa , stable@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20251205213558.2980480-1-david@kernel.org> <20251205213558.2980480-5-david@kernel.org> <0914A8DB-447C-4E62-B151-62E5E4E99749@gmail.com> To: "David Hildenbrand (Red Hat)" X-Mailer: Apple Mail (2.3864.200.81.1.6) > On 7 Dec 2025, at 14:15, Nadav Amit wrote: >=20 >=20 >> On 5 Dec 2025, at 23:35, David Hildenbrand (Red Hat) = wrote: >>=20 >> @@ -400,6 +411,7 @@ static inline void __tlb_reset_range(struct = mmu_gather *tlb) >>=20 >=20 > @@ -400,6 +411,7 @@ static inline void __tlb_reset_range(struct = mmu_gather *tlb) > tlb->cleared_pmds =3D 0; > tlb->cleared_puds =3D 0; > tlb->cleared_p4ds =3D 0; > + tlb->unshared_tables =3D 0; > /* > * Do not reset mmu_gather::vma_* fields here, we do not > * call into tlb_start_vma() again to set them if there is an >=20 > I understand you don=E2=80=99t want to initialize = fully_unshared_tables here, but > tlb_gather_mmu() needs to happen somewhere. So you probably want it to > take place in tlb_gather_mmu(), no? To clarify my messed up response: the code needs to initialize = fully_unshared_tables somewhere during tlb_gather_mmu() invocation.