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Tue, 03 Mar 2026 12:30:16 -0800 (PST) X-Received: by 2002:a05:690e:bcf:b0:64a:db39:f010 with SMTP id 956f58d0204a3-64cc1f34d1dmr14893811d50.0.1772569816232; Tue, 03 Mar 2026 12:30:16 -0800 (PST) MIME-Version: 1.0 References: <20260226012929.169479-1-npache@redhat.com> <20260226012929.169479-4-npache@redhat.com> <25723c0f-c702-44ad-93e9-1056313680cd@kernel.org> <0421d482-a2b0-420c-b83f-1cc057d6662a@kernel.org> In-Reply-To: <0421d482-a2b0-420c-b83f-1cc057d6662a@kernel.org> From: Nico Pache Date: Tue, 3 Mar 2026 13:29:47 -0700 X-Gm-Features: AaiRm52wsoZnP7uPLaOh2G5LImV-hzDx9TaDGRG6Fh4Po-vgQKPJJrvFAeGABZw Message-ID: Subject: Re: [PATCH mm-unstable v2 3/5] mm/khugepaged: define COLLAPSE_MAX_PTES_LIMIT as HPAGE_PMD_NR - 1 To: "David Hildenbrand (Arm)" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jackmanb@google.com, jack@suse.cz, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: z1j7Cl-3ZjMITIOVUIY1OoyE5sgWpza07A03uDFNI4I_1772569817 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9937C1C0015 X-Stat-Signature: kx8dtxpi1wygj9d8ra4emsyksnwnh1yd X-Rspam-User: X-HE-Tag: 1772569819-40445 X-HE-Meta: U2FsdGVkX1/fRaGwU2QWwPdZweu1/GX8gjROVLv+bVWglRnfE35DoPvd+CyAepS5C0BtM4EoDpAsg/Ca6az3Dbkda16BCb2cEE7TAMClNvgrIqLqj1vnqWMCxIkdoEKGBN81eEt+JMStuecDrtvmTy599wv5ViaIpWGxUPJl1CuwHb5lcqrbWXgPXOt8HB+8zXchS5bFrGciy6U5565MzY2peOlaLxaX8dwKc7dTww9/9POczlVfBYFiOjTfQerbgAGySeM/A29SB9Wk3tEvtLGXyvYkITqAAkkHck5+FgKwMgDKnJinGaFLfKJpNUuDVoa1/N0RJAr0Awl9XK4RHd+X1ny5qJh7eaOp6milAaAH6Q9ihagXrFUsqv3Mu9JvZDLIGwCbrPLJB76PcX2PBe+Dzh4zDBpyXEuoFv0yeZuUCdaWBDhqj72055nLKunzaLdckD7qs4YE3Ddsq/YkXcpQXLfJhARTYReUHcYuSNf5xg7jdZgCG8oyWmJdJ8aYHVRvf8ujyzV6cQ3yzdkOm+dxjBSgq4Q11ssK0iBwWCLxqi4C9/WPp0kPcdJj7hikr0B2ldSgjfLG425G84NuedfeODE/jQmSMtVxknQZxrAArYspH7lSINcjG1NSOtYRVD+RVvW7v5btKqeA+TDF+i40POlDdEFkEoJtSIzMd/daQ/AwWEpLrwF/Kwlpd7UfIgvC9PUX1aiiv2u3MlkS1PUO3JIB7ZiRjeA7MZqtgtXJcJBHz1bMeaPqOt/8MwIlH8TghvL0a5Barqo08splK2zosWrJmAX+LQ5M+BvrT0tW+Q/0tBLseqwMKTnAsD9SnPh249CFO6xaiZoULbNMcqTVb+QppeoP0LoPCwcqmWqyBXADatufDN4d7uxeAYEhrwc6pQUOTfJf5QHMU9LaJt6fKRDdy2g3ukldw3TLzEWkt9edhM9O3MvyBvFtn4YDlXQktjBKCnB53DUJQk6 rUMXMPd3 3FHt+RVTDAYfR5cAKfxX8SB2TX1M08YHNda+Img4lJLQ70p5z5bd6Ki4SSx/hi06AKj0e8szLrBOQ1LcDf68I/aZfXrvjDLquZbBmldmHzJHwIN4fsw3ZYvsH341pel+vfBqWZZ7SPWWTy7yYvzz/NsuL1lZpPpEi5ZVba3y6NPp02Y9FDGOildH9IrTFg1qSuR29Ew2o0jYXFcerSTciN/VsngAWQ63NLGG00qtRpuOKwWcoba/sIiZ/V7PxS4Z5GGxGvrUzQskVGI1XfcZm+9stbK8Q7y6nbZJs3X5HfVBcpiY0W9kvx73yqihwRa3Nx7etOLJJ1dXBQdNffnVa/S3+iBExRKeh2shUHyNFimO067GPaSYvpuZ7mKpp3ivU9SmoRlSFtfAiOA9Imri6eqo6a0x9LYPqTuWdt7sqGaYxcqvhVv01i+2/3u2JysmGJQBnRtbH9WHyCLDGHJ+ngYhcBPqHzPZQ/3jy+w9zCUaGOWk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Feb 27, 2026 at 1:53=E2=80=AFAM David Hildenbrand (Arm) wrote: > > On 2/26/26 21:17, Nico Pache wrote: > > On Thu, Feb 26, 2026 at 2:28=E2=80=AFAM David Hildenbrand (Arm) > > wrote: > >> > >> On 2/26/26 02:29, Nico Pache wrote: > >>> The value (HPAGE_PMD_NR - 1) is used often in the khugepaged code to > >>> signify the limit of the max_ptes_* values. Add a define for this to > >>> increase code readability and reuse. > >>> > >>> Acked-by: Pedro Falcato > >>> Reviewed-by: Zi Yan > >>> Signed-off-by: Nico Pache > >>> --- > >>> mm/khugepaged.c | 9 +++++---- > >>> 1 file changed, 5 insertions(+), 4 deletions(-) > >>> > >>> diff --git a/mm/khugepaged.c b/mm/khugepaged.c > >>> index 2ef4b972470b..4615f34911d1 100644 > >>> --- a/mm/khugepaged.c > >>> +++ b/mm/khugepaged.c > >>> @@ -89,6 +89,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); > >>> * > >>> * Note that these are only respected if collapse was initiated by k= hugepaged. > >>> */ > >>> +#define COLLAPSE_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1) > >> > >> I'd call it "KHUGEPAGED_MAX_PTES_LIMIT", because it's khugepaged > >> specific (no madvise) and matches the parameters. > > > > Ok before changing that, note that this is also leveraged in the mTHP > > set. It's technically used for madvise collapse because when it's not > > khugepaged we set max_ptes_none=3D 511. > > It's more about disabling that parameter, right? Yeah, we conditionally set `max_ptes_none =3D ..._MAX_PTES_LIMIT` for the case where no pte limit should be enforced. -- Nico > > -- > Cheers, > > David >