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Shutemov" , Yin Fengwei , David Hildenbrand , Yu Zhao , Catalin Marinas , Will Deacon , Anshuman Khandual , Yang Shi , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 2/5] mm: Allow deferred splitting of arbitrary large anon folios References: <20230703135330.1865927-1-ryan.roberts@arm.com> <20230703135330.1865927-3-ryan.roberts@arm.com> Date: Fri, 07 Jul 2023 16:21:06 +0800 In-Reply-To: <20230703135330.1865927-3-ryan.roberts@arm.com> (Ryan Roberts's message of "Mon, 3 Jul 2023 14:53:27 +0100") Message-ID: <877crcgmj1.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: D2B04180009 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: hmiyxwnud4zdgiy3rqrnknjjrhj53kr9 X-HE-Tag: 1688718168-466480 X-HE-Meta: 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 JFZ1w6vP Rp7wiprTunEAmvRrcQbK0gMIOZEApNtuHbfrafy9C0nJbcLE4P7CewUi6O9IQB+yGJUklO/bNcrBBbLFE+YMKgHgZU1eRbVrpzF7jXERPhSnyq4aO38WCQ3Xyh1bZTYvcxMOdSFGK7Xs9uQ3VseUe9K8dqRB03k8+AMRzcwOYuloNUKsUD1/vlPQmwUA9wDYXLNzS12E/a68cCD9trD1VmjW0cEqXOmg+q5sxkG528t6FgnEvkq10SAv2LbxMMiEM2zyE 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: Ryan Roberts writes: > With the introduction of large folios for anonymous memory, we would > like to be able to split them when they have unmapped subpages, in order > to free those unused pages under memory pressure. So remove the > artificial requirement that the large folio needed to be at least > PMD-sized. > > Signed-off-by: Ryan Roberts > Reviewed-by: Yu Zhao > Reviewed-by: Yin Fengwei > --- > mm/rmap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 82ef5ba363d1..bbcb2308a1c5 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1474,7 +1474,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, > * page of the folio is unmapped and at least one page > * is still mapped. > */ > - if (folio_test_pmd_mappable(folio) && folio_test_anon(folio)) > + if (folio_test_large(folio) && folio_test_anon(folio)) > if (!compound || nr < nr_pmdmapped) > deferred_split_folio(folio); > } One possible issue is that even for large folios mapped only in one process, in zap_pte_range(), we will always call deferred_split_folio() unnecessarily before freeing a large folio. Best Regards, Huang, Ying