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From: Muchun Song In-Reply-To: <20230828090941.GD3223@kernel.org> Date: Mon, 28 Aug 2023 17:18:23 +0800 Cc: Usama Arif , Linux-MM , Mike Kravetz , linux-kernel@vger.kernel.org, Muchun Song , fam.zheng@bytedance.com, liangma@liangbit.com, punit.agrawal@bytedance.com Content-Transfer-Encoding: quoted-printable Message-Id: References: <20230825111836.1715308-1-usama.arif@bytedance.com> <20230825111836.1715308-4-usama.arif@bytedance.com> <20230828074729.GC3223@kernel.org> <2be1ab83-f047-245f-68ad-62c4478914a5@linux.dev> <20230828090941.GD3223@kernel.org> To: Mike Rapoport X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 48A1980004 X-Stat-Signature: uoa1g8o654izkruabowqdfp6pcp7hjyj X-Rspam-User: X-HE-Tag: 1693214329-732214 X-HE-Meta: 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 XFEkryqf yiKEkpNVZdtreX/KlSQWSPCX2viOQ3xqslS0ip+whHb9ykZ3A8Q6MHnsdu5/8I8d4da+YhMk9eh8nSRcBNwZzLiE5KpodoPaho9Cu15x7W1bPW4FZLULTbCe9zWjGb1F6JhW4II94cO2n5Wyz+BghV8dNwh7TKJbAFdmC8lfv4OVDhC/EL1xOEwLDAafY5i1j3M18xhdaIptoUaZqoprrHIbrVUg5WTinmAlCopGy5mHmGmodABv4h66f+oL/I3Ar5y4wtpywmsRjMQuE2CfQGQ6HdEc8zRTYc/KQ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Aug 28, 2023, at 17:09, Mike Rapoport wrote: >=20 > On Mon, Aug 28, 2023 at 04:52:10PM +0800, Muchun Song wrote: >>=20 >>=20 >> On 2023/8/28 15:47, Mike Rapoport wrote: >>> On Fri, Aug 25, 2023 at 12:18:35PM +0100, Usama Arif wrote: >>>> For reserved memory regions marked with this flag, >>>> reserve_bootmem_region is not called during = memmap_init_reserved_pages. >>>> This can be used to avoid struct page initialization for >>>> regions which won't need them, for e.g. hugepages with >>>> HVO enabled. >>>>=20 >>>> Signed-off-by: Usama Arif >>>> --- >>>> include/linux/memblock.h | 10 ++++++++++ >>>> mm/memblock.c | 32 +++++++++++++++++++++++++++----- >>>> 2 files changed, 37 insertions(+), 5 deletions(-) >>>>=20 >>>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >>>> index f71ff9f0ec81..6d681d053880 100644 >>>> --- a/include/linux/memblock.h >>>> +++ b/include/linux/memblock.h >>>> @@ -40,6 +40,8 @@ extern unsigned long long max_possible_pfn; >>>> * via a driver, and never indicated in the firmware-provided = memory map as >>>> * system RAM. This corresponds to = IORESOURCE_SYSRAM_DRIVER_MANAGED in the >>>> * kernel resource tree. >>>> + * @MEMBLOCK_RSRV_NOINIT_VMEMMAP: memory region for which struct = pages are >>>> + * not initialized (only for reserved regions). >>>> */ >>>> enum memblock_flags { >>>> MEMBLOCK_NONE =3D 0x0, /* No special request */ >>>> @@ -47,6 +49,8 @@ enum memblock_flags { >>>> MEMBLOCK_MIRROR =3D 0x2, /* mirrored region */ >>>> MEMBLOCK_NOMAP =3D 0x4, /* don't add to kernel direct mapping */ >>>> MEMBLOCK_DRIVER_MANAGED =3D 0x8, /* always detected via a driver = */ >>>> + /* don't initialize struct pages associated with this reserver = memory block */ >>>> + MEMBLOCK_RSRV_NOINIT_VMEMMAP =3D 0x10, >>> The flag means that struct page shouldn't be initialized, it may be = used >>> not only by vmemmap optimizations. >>> Please drop _VMEMMAP. >>=20 >> The area at where the struct pages located is vmemmap, I think the >> "vmemap" suffix does not mean that it is for "vmemmap optimization", >> it could specify the target which will not be initialized. For me, >> MEMBLOCK_RSRV_NOINIT does not tell me what should not be initialized, >> memblock itself or its struct page (aka vmemmap pages)? So maybe >> the suffix is better to keep? > In general case the area is memmap rather than vmemmap, so a better = suffix Right. memmap > then would be _MEMMAP. I'm not too fond of that either, but I cannot = think > of better name. I have no strong opinion, if we cannot think a better name, just drop = the suffix as you suggested and let the comments more specified. :-) Thanks.