From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DDE323BF88 for ; Mon, 3 Mar 2025 22:55:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741042540; cv=none; b=Lo2oD0NswPkyUBXDcSL74DXDevgSotEVs29VYkht0aV4evz5Rj87P29LyxORNiSm2BPqNbGWJQx5ng4YOcL12yid6GIHDPoLQZSnGtiIdxIQAojp/ch4HtlIx5Fv+w2mC2/+wNeJqBIAVuSGJXh3+3cj6fNWpsosz2aLU8oGziM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741042540; c=relaxed/simple; bh=U9hRw9Rz/hzkkUiqP5kvX1M579YMf8MUvbyoLdDGKpM=; h=Date:To:From:Subject:Message-Id; b=shf7uxn2TSx/rZZGPbkEayJUUwqu8p1EQcA8grDIs+3UstGkhWgzbsIbNX8OqljxLwsA5l/XTOuAmL9JvmzLCjOTsaJujCvGBGdFkbGzOeZqAl74a4dDz6fylaye031e6NKcyT5Zc92ZTvCI95OrykLpCktXUVOJMRvM0/bzi7I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=y5alUWOE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="y5alUWOE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66830C4CEEB; Mon, 3 Mar 2025 22:55:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1741042539; bh=U9hRw9Rz/hzkkUiqP5kvX1M579YMf8MUvbyoLdDGKpM=; h=Date:To:From:Subject:From; b=y5alUWOEDpEYmpOJBr08WloLD57OCHy6wLblQ+WR3527dvCTjBAIrJlUY5Y39JiPw EF/m+MAiNvmfTlaR4deNr8FBLq955f9as2+nobwP7LMAFp+hL7aupxSqCqSnUb8uRB zrqwMZsNM7Je3d870Btw/KNGXMfxfhV+BkLjesbc= Date: Mon, 03 Mar 2025 14:55:38 -0800 To: mm-commits@vger.kernel.org,willy@infradead.org,vbabka@suse.cz,tj@kernel.org,tglx@linutronix.de,muchun.song@linux.dev,mkoutny@suse.com,mingo@redhat.com,luto@kernel.org,lorenzo.stoakes@oracle.com,lizefan.x@bytedance.com,liam.howlett@oracle.com,kirill.shutemov@linux.intel.com,jannh@google.com,ioworker0@gmail.com,hannes@cmpxchg.org,dave.hansen@linux.intel.com,corbet@lwn.net,bp@alien8.de,david@redhat.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page.patch added to mm-unstable branch Message-Id: <20250303225539.66830C4CEEB@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: let _folio_nr_pages overlay memcg_data in first tail page has been added to the -mm mm-unstable branch. Its filename is mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: David Hildenbrand Subject: mm: let _folio_nr_pages overlay memcg_data in first tail page Date: Mon, 3 Mar 2025 17:29:56 +0100 Let's free up some more of the "unconditionally available on 64BIT" space in order-1 folios by letting _folio_nr_pages overlay memcg_data in the first tail page (second folio page). Consequently, we have the optimization now whenever we have CONFIG_MEMCG, independent of 64BIT. We have to make sure that page->memcg on tail pages does not return "surprises". page_memcg_check() already properly refuses PageTail(). Let's do that earlier in print_page_owner_memcg() to avoid printing wrong "Slab cache page" information. No other code should touch that field on tail pages of compound pages. Reset the "_nr_pages" to 0 when splitting folios, or when freeing them back to the buddy (to avoid false page->memcg_data "bad page" reports). Note that in __split_huge_page(), folio_nr_pages() would stop working already as soon as we start messing with the subpages. Most kernel configs should have at least CONFIG_MEMCG enabled, even if disabled at runtime. 64byte "struct memmap" is what we usually have on 64BIT. While at it, rename "_folio_nr_pages" to "_nr_pages". Hopefully memdescs / dynamically allocating "strut folio" in the future will further clean this up, e.g., making _nr_pages available in all configs and maybe even in small folios. Doing that should be fairly easy on top of this change. Link: https://lkml.kernel.org/r/20250303163014.1128035-4-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Kirill A. Shutemov Cc: Andy Lutomirks^H^Hski Cc: Borislav Betkov Cc: Dave Hansen Cc: Ingo Molnar Cc: Jann Horn Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Lance Yang Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcow (Oracle) Cc: Michal Koutn Cc: Muchun Song Cc: tejun heo Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Zefan Li Signed-off-by: Andrew Morton --- include/linux/mm.h | 4 ++-- include/linux/mm_types.h | 30 ++++++++++++++++++++++-------- mm/huge_memory.c | 16 +++++++++++++--- mm/internal.h | 4 ++-- mm/page_alloc.c | 6 +++++- mm/page_owner.c | 2 +- 6 files changed, 45 insertions(+), 17 deletions(-) --- a/include/linux/mm.h~mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page +++ a/include/linux/mm.h @@ -1199,10 +1199,10 @@ static inline unsigned int folio_large_o return folio->_flags_1 & 0xff; } -#ifdef CONFIG_64BIT +#ifdef NR_PAGES_IN_LARGE_FOLIO static inline long folio_large_nr_pages(const struct folio *folio) { - return folio->_folio_nr_pages; + return folio->_nr_pages; } #else static inline long folio_large_nr_pages(const struct folio *folio) --- a/include/linux/mm_types.h~mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page +++ a/include/linux/mm_types.h @@ -287,6 +287,11 @@ typedef struct { unsigned long val; } swp_entry_t; +#if defined(CONFIG_MEMCG) || defined(CONFIG_SLAB_OBJ_EXT) +/* We have some extra room after the refcount in tail pages. */ +#define NR_PAGES_IN_LARGE_FOLIO +#endif + /** * struct folio - Represents a contiguous set of bytes. * @flags: Identical to the page flags. @@ -312,7 +317,7 @@ typedef struct { * @_large_mapcount: Do not use directly, call folio_mapcount(). * @_nr_pages_mapped: Do not use outside of rmap and debug code. * @_pincount: Do not use directly, call folio_maybe_dma_pinned(). - * @_folio_nr_pages: Do not use directly, call folio_nr_pages(). + * @_nr_pages: Do not use directly, call folio_nr_pages(). * @_hugetlb_subpool: Do not use directly, use accessor in hugetlb.h. * @_hugetlb_cgroup: Do not use directly, use accessor in hugetlb_cgroup.h. * @_hugetlb_cgroup_rsvd: Do not use directly, use accessor in hugetlb_cgroup.h. @@ -377,13 +382,20 @@ struct folio { unsigned long _flags_1; unsigned long _head_1; /* public: */ - atomic_t _large_mapcount; - atomic_t _entire_mapcount; - atomic_t _nr_pages_mapped; - atomic_t _pincount; -#ifdef CONFIG_64BIT - unsigned int _folio_nr_pages; -#endif + union { + struct { + atomic_t _large_mapcount; + atomic_t _entire_mapcount; + atomic_t _nr_pages_mapped; + atomic_t _pincount; + }; + unsigned long _usable_1[4]; + }; + atomic_t _mapcount_1; + atomic_t _refcount_1; +#ifdef NR_PAGES_IN_LARGE_FOLIO + unsigned int _nr_pages; +#endif /* NR_PAGES_IN_LARGE_FOLIO */ /* private: the union with struct page is transitional */ }; struct page __page_1; @@ -435,6 +447,8 @@ FOLIO_MATCH(_last_cpupid, _last_cpupid); offsetof(struct page, pg) + sizeof(struct page)) FOLIO_MATCH(flags, _flags_1); FOLIO_MATCH(compound_head, _head_1); +FOLIO_MATCH(_mapcount, _mapcount_1); +FOLIO_MATCH(_refcount, _refcount_1); #undef FOLIO_MATCH #define FOLIO_MATCH(pg, fl) \ static_assert(offsetof(struct folio, fl) == \ --- a/mm/huge_memory.c~mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page +++ a/mm/huge_memory.c @@ -3307,10 +3307,11 @@ bool can_split_folio(struct folio *folio * It splits @folio into @new_order folios and copies the @folio metadata to * all the resulting folios. */ -static void __split_folio_to_order(struct folio *folio, int new_order) +static void __split_folio_to_order(struct folio *folio, int old_order, + int new_order) { - long nr_pages = folio_nr_pages(folio); long new_nr_pages = 1 << new_order; + long nr_pages = 1 << old_order; long index; /* @@ -3528,12 +3529,21 @@ static int __split_unmapped_folio(struct } } + /* + * Reset any memcg data overlay in the tail pages. + * folio_nr_pages() is unreliable until prep_compound_page() + * was called again. + */ +#ifdef NR_PAGES_IN_LARGE_FOLIO + folio->_nr_pages = 0; +#endif + /* complete memcg works before add pages to LRU */ split_page_memcg(&folio->page, old_order, split_order); split_page_owner(&folio->page, old_order, split_order); pgalloc_tag_split(folio, old_order, split_order); - __split_folio_to_order(folio, split_order); + __split_folio_to_order(folio, old_order, split_order); after_split: /* --- a/mm/internal.h~mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page +++ a/mm/internal.h @@ -682,8 +682,8 @@ static inline void folio_set_order(struc return; folio->_flags_1 = (folio->_flags_1 & ~0xffUL) | order; -#ifdef CONFIG_64BIT - folio->_folio_nr_pages = 1U << order; +#ifdef NR_PAGES_IN_LARGE_FOLIO + folio->_nr_pages = 1U << order; #endif } --- a/mm/page_alloc.c~mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page +++ a/mm/page_alloc.c @@ -1178,8 +1178,12 @@ __always_inline bool free_pages_prepare( if (unlikely(order)) { int i; - if (compound) + if (compound) { page[1].flags &= ~PAGE_FLAGS_SECOND; +#ifdef NR_PAGES_IN_LARGE_FOLIO + folio->_nr_pages = 0; +#endif + } for (i = 1; i < (1 << order); i++) { if (compound) bad += free_tail_page_prepare(page, page + i); --- a/mm/page_owner.c~mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page +++ a/mm/page_owner.c @@ -507,7 +507,7 @@ static inline int print_page_owner_memcg rcu_read_lock(); memcg_data = READ_ONCE(page->memcg_data); - if (!memcg_data) + if (!memcg_data || PageTail(page)) goto out_unlock; if (memcg_data & MEMCG_DATA_OBJEXTS) _ Patches currently in -mm which might be from david@redhat.com are mm-gup-reject-foll_split_pmd-with-hugetlb-vmas.patch mm-rmap-reject-hugetlb-folios-in-folio_make_device_exclusive.patch mm-rmap-convert-make_device_exclusive_range-to-make_device_exclusive.patch mm-rmap-convert-make_device_exclusive_range-to-make_device_exclusive-fix.patch mm-rmap-implement-make_device_exclusive-using-folio_walk-instead-of-rmap-walk.patch mm-memory-detect-writability-in-restore_exclusive_pte-through-can_change_pte_writable.patch mm-use-single-swp_device_exclusive-entry-type.patch mm-page_vma_mapped-device-exclusive-entries-are-not-migration-entries.patch kernel-events-uprobes-handle-device-exclusive-entries-correctly-in-__replace_page.patch mm-ksm-handle-device-exclusive-entries-correctly-in-write_protect_page.patch mm-rmap-handle-device-exclusive-entries-correctly-in-try_to_unmap_one.patch mm-rmap-handle-device-exclusive-entries-correctly-in-try_to_migrate_one.patch mm-rmap-handle-device-exclusive-entries-correctly-in-page_vma_mkclean_one.patch mm-page_idle-handle-device-exclusive-entries-correctly-in-page_idle_clear_pte_refs_one.patch mm-damon-handle-device-exclusive-entries-correctly-in-damon_folio_young_one.patch mm-damon-handle-device-exclusive-entries-correctly-in-damon_folio_mkold_one.patch mm-rmap-keep-mapcount-untouched-for-device-exclusive-entries.patch mm-rmap-avoid-ebusy-from-make_device_exclusive.patch lib-test_hmm-make-dmirror_atomic_map-consume-a-single-page.patch mm-memory-remove-pageanonexclusive-sanity-check-in-restore_exclusive_pte.patch mm-memory-pass-folio-and-pte-to-restore_exclusive_pte.patch mm-memory-document-restore_exclusive_pte.patch mm-mmu_notifier-use-mmu_notify_clear-in-remove_device_exclusive_entry.patch mm-factor-out-large-folio-handling-from-folio_order-into-folio_large_order.patch mm-factor-out-large-folio-handling-from-folio_nr_pages-into-folio_large_nr_pages.patch mm-let-_folio_nr_pages-overlay-memcg_data-in-first-tail-page.patch mm-move-hugetlb-specific-things-in-folio-to-page.patch mm-move-_pincount-in-folio-to-page-on-32bit.patch mm-move-_entire_mapcount-in-folio-to-page-on-32bit.patch mm-rmap-pass-dst_vma-to-folio_dup_file_rmap_pte-and-friends.patch mm-rmap-pass-vma-to-__folio_add_rmap.patch mm-rmap-abstract-large-mapcount-operations-for-large-folios-hugetlb.patch bit_spinlock-__always_inline-unlock-functions.patch mm-rmap-use-folio_large_nr_pages-in-add-remove-functions.patch mm-rmap-basic-mm-owner-tracking-for-large-folios-hugetlb.patch mm-copy-on-write-cow-reuse-support-for-pte-mapped-thp.patch mm-convert-folio_likely_mapped_shared-to-folio_maybe_mapped_shared.patch mm-config_no_page_mapcount-to-prepare-for-not-maintain-per-page-mapcounts-in-large-folios.patch fs-proc-page-remove-per-page-mapcount-dependency-for-proc-kpagecount-config_no_page_mapcount.patch fs-proc-task_mmu-remove-per-page-mapcount-dependency-for-pm_mmap_exclusive-config_no_page_mapcount.patch fs-proc-task_mmu-remove-per-page-mapcount-dependency-for-mapmax-config_no_page_mapcount.patch fs-proc-task_mmu-remove-per-page-mapcount-dependency-for-smaps-smaps_rollup-config_no_page_mapcount.patch mm-stop-maintaining-the-per-page-mapcount-of-large-folios-config_no_page_mapcount.patch