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Mon, 02 Nov 2026 02:49:51 +0000 X-Mizu-Trace-ID: 348b45477b4b0c16 X-Migadu-Flow: FLOW_OUT From: Kaitao Cheng To: Muchun Song , Oscar Salvador , David Hildenbrand , Andrew Morton , Mike Rapoport , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt Cc: Mani Tofigh , Zi Yan , Mike Kravetz , Baolin Wang , Miaohe Lin , Naoya Horiguchi , Frank van der Linden , Chris Down , Joshua Hahn , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Kaitao Cheng Subject: [PATCH v2 2/3] mm/hugetlb: Preserve persistent flags when returning folios to the pool Date: Mon, 2 Nov 2026 10:49:09 +0800 Message-ID: <20261102024910.31486-3-kaitao.cheng@linux.dev> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261102024910.31486-1-kaitao.cheng@linux.dev> References: <20261102024910.31486-1-kaitao.cheng@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 5F22D20002 X-Stat-Signature: snkihji9ktjc79hars6ad68msi9344tq X-Rspam-User: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793587794-509246 X-HE-Meta: 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 H5OFy9Qe vsIdWwDF9yJoSP2PZpmHHZel5vcySGgqPcgG5rPDzmD9oRMJp/voHjlINUSyA0s0FfeF3bABpvG1rRjBK+xGUhiZf+uwoXON7jJxToaDC3OWuemnpjZe7n+er5SFjJ6AnueyaMtaEL8Z8EddZY0SNmplHatNBtBBRGDHt3L8OqZBStlo+1idr53IrMask/W0Dg1rVdLD5pqNZe/ZxTgUoZvOVJl1XHopsuddnR9GihgA0PD0UxL8/lSTJWErtOKtifLKpNoJxSPW61uW63a+hAzjplYBU8XjXbA4SE9mBUUy+9fohkXLz2dHPkPWtBTeUwmkW/s3JVPao/7YbiFD9JD+o/ptCBw6ISeWQ9DrltU0IzW03aZGPDVRsFYXgag5o1ZYgcu1TiNQLxrulfHD7+FxthC0t9TaC9eK2 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Kaitao Cheng add_hugetlb_folio() returns a folio to the HugeTLB pool when vmemmap restoration fails. It clears folio->private and restores only HPG_vmemmap_optimized, losing other flags that must survive the rollback. Clearing HPG_cma causes a later free to bypass the CMA release path, leaving the CMA allocation bitmap set. Clearing HPG_raw_hwp_unreliable loses the indication that the locations of poisoned subpages are unknown, undermining the checks that prevent freeing or unpoisoning such folios. Preserve the existing flags instead of resetting folio->private. Callers already clear HPG_restore_reserve, HPG_migratable and HPG_freed before returning a folio to the pool. Clear HPG_temporary in free_huge_folio() before attempting to free a temporary folio, so a failed vmemmap restore does not leave that flag set on a folio returned as surplus. Add a VM_WARN_ON_ONCE_FOLIO() check for flags other than HPG_vmemmap_optimized, HPG_raw_hwp_unreliable and HPG_cma to detect incomplete transient flag cleanup. Fixes: 161df60e9e89 ("mm, hwpoison, hugetlb: support saving mechanism of raw error pages") Fixes: d2d786714080 ("mm/hugetlb: enable bootmem allocation from CMA areas") Closes: https://sashiko.dev/#/bug/linux-5363eb09-9c3c-4f8b-9f3c-a998a8c4b258 Suggested-by: David Hildenbrand Suggested-by: Muchun Song Suggested-by: Zi Yan Signed-off-by: Kaitao Cheng --- mm/hugetlb.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 4a008afaedf9..931ca3a30773 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1443,6 +1443,12 @@ void add_hugetlb_folio(struct hstate *h, struct folio *folio, lockdep_assert_held(&hugetlb_lock); + /* Callers must clear transient flags before returning to the pool. */ + VM_WARN_ON_ONCE_FOLIO((unsigned long)folio->private & + ~(BIT(HPG_vmemmap_optimized) | + BIT(HPG_raw_hwp_unreliable) | + BIT(HPG_cma)), folio); + INIT_LIST_HEAD(&folio->lru); h->nr_huge_pages++; h->nr_huge_pages_node[nid]++; @@ -1453,9 +1459,6 @@ void add_hugetlb_folio(struct hstate *h, struct folio *folio, } __folio_set_hugetlb(folio); - /* Clear all folio->private flags except hugetlb_vmemmap_optimized. */ - folio->private = NULL; - folio_set_hugetlb_vmemmap_optimized(folio); arch_clear_hugetlb_flags(folio); enqueue_hugetlb_folio(h, folio); @@ -1743,6 +1746,7 @@ void free_huge_folio(struct folio *folio) h->resv_huge_pages++; if (folio_test_hugetlb_temporary(folio)) { + folio_clear_hugetlb_temporary(folio); remove_hugetlb_folio(h, folio, false); spin_unlock_irqrestore(&hugetlb_lock, flags); update_and_free_hugetlb_folio(h, folio, true); -- 2.54.0 (Apple Git-157)