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Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn Subject: Re: [PATCH v3 20/20] mm: stop maintaining the per-page mapcount of large folios (CONFIG_NO_PAGE_MAPCOUNT) Message-ID: <20251014122335.dpyk5advbkioojnm@master> Reply-To: Wei Yang References: <20250303163014.1128035-1-david@redhat.com> <20250303163014.1128035-21-david@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250303163014.1128035-21-david@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) On Mon, Mar 03, 2025 at 05:30:13PM +0100, David Hildenbrand wrote: [...] >@@ -1678,6 +1726,22 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, > break; > case RMAP_LEVEL_PMD: > case RMAP_LEVEL_PUD: >+ if (IS_ENABLED(CONFIG_NO_PAGE_MAPCOUNT)) { >+ last = atomic_add_negative(-1, &folio->_entire_mapcount); >+ if (level == RMAP_LEVEL_PMD && last) >+ nr_pmdmapped = folio_large_nr_pages(folio); >+ nr = folio_dec_return_large_mapcount(folio, vma); >+ if (!nr) { >+ /* Now completely unmapped. */ >+ nr = folio_large_nr_pages(folio); >+ } else { >+ partially_mapped = last && >+ nr < folio_large_nr_pages(folio); Hi, David Do you think this is better to be? partially_mapped = last && nr < nr_pmdmapped; As commit 349994cf61e6 mentioned, we don't support partially mapped PUD-sized folio yet. Not sure what I missed here. >+ nr = 0; >+ } >+ break; >+ } >+ > folio_dec_large_mapcount(folio, vma); > last = atomic_add_negative(-1, &folio->_entire_mapcount); > if (last) { >-- >2.48.1 > -- Wei Yang Help you, Help me