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Ka0/Iedm/fNlZeXI1LswepKVlz2AEbbKDPPKIVSlIs5eYiTgbHUOz8K3IlQRzkwxKG9TH/Exnka/qIJBZ5IsE8gy0Wai24FZv3FmsCJ9M/AUtvEZSXEdmst7NDpCLPduTS20lQiVfWJ0lFKd6Vk6KRhsXs8E2pk59ECRURYEuNzqw9Z2EOx1Vbbyqn6iuh/hFJyHYvd1OAHc+EXjZNBaCr/jdfO+nALT41JxV/yCv9NVieUSagQrA6xQj74sVQhJKsD1T8WwRWZSCZpAxX999pP8JtgECsEfDAa/wqKwU8hgpXfM/eswgrXtF7S2dDf+5eMik4GNEImeFuKw2oESjg86SUKQyt368epq4O+2u+KKjKPKcAFtU3SEZd3D1+GDYyXtozyncfEMDTBK2FFLAVjZKRy4iae+5jSdo9k584BhM19UjgswqpcsWlg== 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: List-Subscribe: List-Unsubscribe: --=_MailMate_5AA9C52F-3C17-4BAB-8ABC-EE01248E817D_= Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 8 Oct 2024, at 9:06, David Hildenbrand wrote: > On 08.10.24 14:57, Vlastimil Babka wrote: >> On 10/8/24 13:52, Zi Yan wrote: >>> On 8 Oct 2024, at 4:26, David Hildenbrand wrote: >>> >>>> >>>> I remember we discussed that in the past and that we do *not* want t= o sprinkle these CONFIG_INIT_ON_ALLOC_DEFAULT_ON checks all over the kern= el. >>>> >>>> Ideally, we'd use GFP_ZERO and have the buddy just do that for us? T= here is the slight chance that we zero-out when we're not going to use th= e allocated folio, but ... that can happen either way even with the curre= nt code? >>> >>> I agree that putting CONFIG_INIT_ON_ALLOC_DEFAULT_ON here is not idea= l, but >> >> Create some nice inline wrapper for the test and it will look less ugl= y? :) something like? static inline bool alloc_zeroed() { return static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, &init_on_alloc); } I missed another folio_zero_user() caller in alloc_anon_folio() for mTHP.= So both PMD THP and mTHP are zeroed twice for all arch. Adding Ryan for mTHP. >> >>> folio_zero_user() uses vmf->address to improve cache performance by c= hanging >>> subpage clearing order. See commit c79b57e462b5 ("mm: hugetlb: clear = target >>> sub-page last when clearing huge page=E2=80=9D). If we use GFP_ZERO, = we lose this >>> optimization. To keep it, vmf->address will need to be passed to allo= cation >>> code. Maybe that is acceptable? >> >> I'd rather not change the page allocation code for this... > > Although I'm curious if that optimization from 2017 is still valuable := ) Maybe Ying can give some insight on this. Do we need some general guidance on who is responsible for zeroing alloca= ted folios? Should people use GFP_ZERO instead of zeroing by themselves if po= ssible? Best Regards, Yan, Zi --=_MailMate_5AA9C52F-3C17-4BAB-8ABC-EE01248E817D_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEEh7yFAW3gwjwQ4C9anbJR82th+ooFAmcFN7QPHHppeUBudmlk aWEuY29tAAoJEJ2yUfNrYfqKrxQP/3P24uVMN6E67bbuZCRTeBXHbLDcJDCqhYGb 6loGgfyfPkolxsES9BhBR9rvexe/bdXShconru/gKx6TszjNZJ328sMeTLBi+DY2 UMjbZamSPfOBqMNDCEhq46GaCDmD8fz+9aL3PqifPMv+rnrhs0YRnfQ4EnGxGGds z6M5GFQORaX/tjtpHY4kTG/VO6Er7+WQwyZ8WcxPIT/uVWST+Werx7UbgbRPRFlo YnTa2Hf6Kcz2E50L6VoNiz7XHUGcurS4lRU1pwds12joaaQvwmaK6JK3dzXZy6Ls CYcMMfGHTWEsL5Sjb8zlffrNCdb/4CI1bHrjPGW6MpxMynh/u1uQRtRoTfymLqod /6x7ocX1W/ldyie2cVQyWUd9fVKj9cOoDKk8m8r66igCBW0Urxqs2fAm7a6RuKIc o3cjl6t5Jb6SYFn7/iW2I7vevY5tVrKs5yKLJ0EZ5iRowcQNOlH9o+GbTy8ynoaj Lu7uW7wr5JAhdO0yB4mImbbBIVxcE8bIvJkVpdzb+NLYvEuTCRA5N99uoqdSI6IR cuFjQfYqHYqSAaNuOa7ALQhbzKT8f5LPmA6r50U1KzmkePYqpgMIbJDZuujwckXd QExvWb4te/ROsvlWfRaUaKwqiw2NxI83UQhU8WxYDn+Fzdzbcdu6cgd/ry/jHDzL gY6Krycw =sQIt -----END PGP SIGNATURE----- --=_MailMate_5AA9C52F-3C17-4BAB-8ABC-EE01248E817D_=--