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Fri, 06 Nov 2026 10:06:06 +0000 X-Mizu-Trace-ID: f3d9d3dc338d93a1 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 , Qi Zheng Subject: [PATCH v3 2/4] mm/hugetlb: Preserve persistent flags when returning folios to the pool Date: Fri, 6 Nov 2026 18:05:19 +0800 Message-ID: <20261106100521.30099-3-kaitao.cheng@linux.dev> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261106100521.30099-1-kaitao.cheng@linux.dev> References: <20261106100521.30099-1-kaitao.cheng@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 9q5t711x7a476to7h5dezwioak94dnm6 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-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 99127A0002 X-HE-Tag: 1793959567-208569 X-HE-Meta: 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 qOG181kO t+P0yneRqYifgA4QpiQgqzqsDGD/VSllNBHhQ+xRKiSRVxaQonassxoJFj5gvf454C1YaET1T+aUAuIkiEjg6avXc7IPCptaY/seTtHadQUp/GBx/kBk/J9uWqKObkcGPvDnvARRfo7bhkB775a9vba7MGF/EEu6TOrF4U76HLV5yaGjDbw+dThMAwm8GaOA/pvc/oCrrxhsoKmI0b2R3K818I5SlZNizGgBeS7PSbz+U3Ypcw7SzPJx982ZIdth3sB4EuMAuXsF1DlJYNP6khTuX+xjiPEvX3c9wN0XRXfmfyIsgdwPjEFv6RR6F6Vwmhlk0WB0ukUKAU0KVXw5P8T1f9yBtQkcPj2RKP+kqdRH0oNAO/lvpFUMg90X0ITbrs0I2Krnv5BiYgZxy8oiJlbK6Dg== 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 Acked-by: Muchun Song Acked-by: Zi Yan Acked-by: Qi Zheng 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 6fba92b0f674..5b5353ff5ee2 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1450,6 +1450,12 @@ 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]++; @@ -1460,9 +1466,6 @@ 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); @@ -1750,6 +1753,7 @@ 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); -- 2.53.0