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Subject: Re: [PATCH v5 17/17] mm/page-flags: remove PG_private
Date: Mon, 21 Sep 2026 02:55:20 +0000 [thread overview]
Message-ID: <20260921025520.628971F000FF@smtp.kernel.org> (raw)
In-Reply-To: <20260920-remove-pg_private-v5-17-bb68b6a21869@nvidia.com>
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] mm: silent memory leak masking due to PG_private removal
--
commit aee12ed3446e69cb6eee57384ca09e768dab36dd
Author: Zi Yan <ziy@nvidia.com>
mm/page-flags: remove PG_private
This commit removes the PG_private page flag and replaces its usage with
checking if folio->private != NULL. The space left by PG_private is
reserved as PG_folio for future use.
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 7080a6a1a79e7..b0ddc652e76cc 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
[ ... ]
> @@ -1169,7 +1175,7 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page)
> */
> #define PAGE_FLAGS_CHECK_AT_FREE \
> (1UL << PG_lru | 1UL << PG_locked | \
> - 1UL << PG_private | 1UL << PG_private_2 | \
> + 1UL << PG_private_2 | \
[Severity: Medium]
Since PG_private is removed from PAGE_FLAGS_CHECK_AT_FREE, does this bypass
the safety check that ensures a page doesn't have uncleared private data?
Looking at __free_pages_prepare() in mm/page_alloc.c:
page_cpupid_reset_last(page);
page->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP;
page->private = 0;
reset_page_owner(page, order);
The head page's private field is silently zeroed here without any prior
verification that it was NULL. Previously, free_page_is_bad() would catch
and report leaked data via a bad_page() warning using
PAGE_FLAGS_CHECK_AT_FREE.
Now, if a buggy filesystem fails to detach and free folio->private data
before freeing the page, will this result in silent memory leaks?
> 1UL << PG_writeback | 1UL << PG_reserved | \
> 1UL << PG_active | \
> 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK)
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260920-remove-pg_private-v5-0-bb68b6a21869@nvidia.com?part=17
next prev parent reply other threads:[~2026-09-21 2:55 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-21 2:27 [PATCH v5 00/17] Remove PG_private by using page/folio->private checks instead Zi Yan
2026-09-21 2:27 ` [PATCH v5 01/17] mm/zsmalloc: replace PG_private with pointer comparison Zi Yan
2026-09-21 6:02 ` Lance Yang
2026-09-21 2:27 ` [PATCH v5 02/17] perf/ring_buffer: stop using PG_private as AUX page high-order marker Zi Yan
2026-09-21 6:19 ` Lance Yang
2026-09-21 2:27 ` [PATCH v5 03/17] xen/grant-table: stop setting PG_private on pages for grant mapping Zi Yan
2026-09-21 7:00 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 04/17] fscrypt: stop setting PG_private on bounce page Zi Yan
2026-09-21 7:03 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 05/17] mm/hugetlb: use direct assignment instead of folio_change_private() Zi Yan
2026-09-21 7:11 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 06/17] f2fs: stop using PG_private Zi Yan
2026-09-21 7:24 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 07/17] f2fs: convert the ->private flag helpers to folio-only Zi Yan
2026-09-21 7:39 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 08/17] erofs: mm/pagemap: add readahead_folio_last() to avoid folio->private Zi Yan
2026-09-21 8:20 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 09/17] erofs: use folio_attach/detach_private() instead of direct assignment Zi Yan
2026-09-21 8:45 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 10/17] mm/page-flags: check page/folio->private instead of PG_private Zi Yan
2026-09-21 9:22 ` David Hildenbrand (Arm)
2026-09-21 2:28 ` [PATCH v5 11/17] treewide: remove folio_set/clear_private() usage Zi Yan
2026-09-21 2:28 ` [PATCH v5 12/17] ceph: replace PagePrivate() with page_private() Zi Yan
2026-09-21 2:28 ` [PATCH v5 13/17] md: Use folio_alloc_buffers() Zi Yan
2026-09-21 9:23 ` David Hildenbrand (Arm)
2026-09-21 2:28 ` [PATCH v5 14/17] md: Use folio APIs in free_page() Zi Yan
2026-09-21 2:28 ` [PATCH v5 15/17] md: Remove the last use of page_buffers() Zi Yan
2026-09-21 2:28 ` [PATCH v5 16/17] treewide: remove PagePrivate() and PG_private from comments and docs Zi Yan
2026-09-21 2:28 ` [PATCH v5 17/17] mm/page-flags: remove PG_private Zi Yan
2026-09-21 2:55 ` sashiko-bot [this message]
2026-09-21 15:36 ` Zi Yan
2026-09-21 4:08 ` [PATCH v5 00/17] Remove PG_private by using page/folio->private checks instead Andrew Morton
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