The patch titled
Subject: trace/events/page_ref: trace the raw page mapcount value
has been added to the -mm mm-unstable branch. Its filename is
trace-events-page_ref-trace-the-raw-page-mapcount-value.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/trace-events-page_ref-trace-the-raw-page-mapcount-value.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: trace/events/page_ref: trace the raw page mapcount value
Date: Tue, 9 Apr 2024 21:22:58 +0200
We want to limit the use of page_mapcount() to the places where it is
absolutely necessary. We already trace raw page->refcount, raw
page->flags and raw page->mapping, and don't involve any folios. Let's
also trace the raw mapcount value that does not consider the entire
mapcount of large folios, and we don't add "1" to it.
When dealing with typed folios, this makes a lot more sense. ... and
it's for debugging purposes only either way.
Link: https://lkml.kernel.org/r/20240409192301.907377-16-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Richard Chang <richardycc@xxxxxxxxxx>
Cc: Rich Felker <dalias@xxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/trace/events/page_ref.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/include/trace/events/page_ref.h~trace-events-page_ref-trace-the-raw-page-mapcount-value
+++ a/include/trace/events/page_ref.h
@@ -30,7 +30,7 @@ DECLARE_EVENT_CLASS(page_ref_mod_templat
__entry->pfn = page_to_pfn(page);
__entry->flags = page->flags;
__entry->count = page_ref_count(page);
- __entry->mapcount = page_mapcount(page);
+ __entry->mapcount = atomic_read(&page->_mapcount);
__entry->mapping = page->mapping;
__entry->mt = get_pageblock_migratetype(page);
__entry->val = v;
@@ -79,7 +79,7 @@ DECLARE_EVENT_CLASS(page_ref_mod_and_tes
__entry->pfn = page_to_pfn(page);
__entry->flags = page->flags;
__entry->count = page_ref_count(page);
- __entry->mapcount = page_mapcount(page);
+ __entry->mapcount = atomic_read(&page->_mapcount);
__entry->mapping = page->mapping;
__entry->mt = get_pageblock_migratetype(page);
__entry->val = v;
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-madvise-make-madv_populate_readwrite-handle-vm_fault_retry-properly.patch
mm-madvise-dont-perform-madvise-vma-walk-for-madv_populate_readwrite.patch
mm-userfaultfd-dont-place-zeropages-when-zeropages-are-disallowed.patch
s390-mm-re-enable-the-shared-zeropage-for-pv-and-skeys-kvm-guests.patch
mm-convert-folio_estimated_sharers-to-folio_likely_mapped_shared.patch
mm-convert-folio_estimated_sharers-to-folio_likely_mapped_shared-fix.patch
selftests-memfd_secret-add-vmsplice-test.patch
mm-merge-folio_is_secretmem-and-folio_fast_pin_allowed-into-gup_fast_folio_allowed.patch
mm-optimize-config_per_vma_lock-member-placement-in-vm_area_struct.patch
mm-remove-prot-parameter-from-move_pte.patch
mm-gup-consistently-name-gup-fast-functions.patch
mm-treewide-rename-config_have_fast_gup-to-config_have_gup_fast.patch
mm-use-gup-fast-instead-fast-gup-in-remaining-comments.patch
drivers-virt-acrn-fix-pfnmap-pte-checks-in-acrn_vm_ram_map.patch
mm-pass-vma-instead-of-mm-to-follow_pte.patch
mm-follow_pte-improvements.patch
mm-allow-for-detecting-underflows-with-page_mapcount-again.patch
mm-rmap-always-inline-anon-file-rmap-duplication-of-a-single-pte.patch
mm-rmap-add-fast-path-for-small-folios-when-adding-removing-duplicating.patch
mm-track-mapcount-of-large-folios-in-single-value.patch
mm-improve-folio_likely_mapped_shared-using-the-mapcount-of-large-folios.patch
mm-make-folio_mapcount-return-0-for-small-typed-folios.patch
mm-memory-use-folio_mapcount-in-zap_present_folio_ptes.patch
mm-huge_memory-use-folio_mapcount-in-zap_huge_pmd-sanity-check.patch
mm-memory-failure-use-folio_mapcount-in-hwpoison_user_mappings.patch
mm-page_alloc-use-folio_mapped-in-__alloc_contig_migrate_range.patch
mm-migrate-use-folio_likely_mapped_shared-in-add_page_for_migration.patch
sh-mm-cache-use-folio_mapped-in-copy_from_user_page.patch
mm-filemap-use-folio_mapcount-in-filemap_unaccount_folio.patch
mm-migrate_device-use-folio_mapcount-in-migrate_vma_check_page.patch
trace-events-page_ref-trace-the-raw-page-mapcount-value.patch
xtensa-mm-convert-check_tlb_entry-to-sanity-check-folios.patch
mm-debug-print-only-page-mapcount-excluding-folio-entire-mapcount-in-__dump_folio.patch
documentation-admin-guide-cgroup-v1-memoryrst-dont-reference-page_mapcount.patch
