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 704FA2DECCB; Thu, 14 May 2026 00:40:45 +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=1778719245; cv=none; b=C3Mc4I6eKnAhTe5XWB6g1kmIto5EcQxZQ56dsuld4t+j7bBh4Uc5llpsOOKwUZ1ca554049RBhU/40zlPpLkLW9USySNUjhWoyU/xuPUIutkhj1ndBSuFoV0Ca14sj2inAjOlB3SEmmRSN/1MnmN1ialuMSLnQJYpoCwAD+b/8c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778719245; c=relaxed/simple; bh=XAyeEy4GxA9PfJacGuRzD6P63mOdoJPc92cyjAAm2EQ=; h=Date:To:From:Subject:Message-Id; b=qDex4zsKnjU1HtrNQV89J5Z7FJJ3wh4j60BTPtovIrpNAOEaub8GEghpCrkgN27u1L0I+3xT9PBFp6qcwxA/J3sEy0GffPjzH5cTN55d8qNk/hW993FujKRx7LQmRMc1uwvSJaZ36NmDneP/0eX0lSxk5Yo+bhmJRJQoFyjimqs= 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=j44iKPug; 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="j44iKPug" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF563C19425; Thu, 14 May 2026 00:40:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1778719245; bh=XAyeEy4GxA9PfJacGuRzD6P63mOdoJPc92cyjAAm2EQ=; h=Date:To:From:Subject:From; b=j44iKPug4Vb+PoskZ+VHjQcN98W5kXwhCst+YiOFwa8el+YnAn0VuLOecuQLbuvLe x18J4pcf44CWIs1D7uolcMO/m9WeQcF3etwCSOAwUbDmGdQutc5Xq4A3P2L+9RO4+b JSWJrQzH/CapZdMdlrkbz8ejR2r9Z2g2u0Pb78vU= Date: Wed, 13 May 2026 17:40:44 -0700 To: mm-commits@vger.kernel.org,vbabka@kernel.org,surenb@google.com,stable@vger.kernel.org,rppt@kernel.org,osalvador@suse.de,mhocko@suse.com,maobibo@loongson.cn,ljs@kernel.org,liam@infradead.org,lance.yang@linux.dev,hughd@google.com,baolin.wang@linux.alibaba.com,david@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-fix-__vm_normal_page-to-handle-missing-support-for-pmd_special-pud_special.patch removed from -mm tree Message-Id: <20260514004044.EF563C19425@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special() has been removed from the -mm tree. Its filename was mm-fix-__vm_normal_page-to-handle-missing-support-for-pmd_special-pud_special.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: "David Hildenbrand (Arm)" Subject: mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special() Date: Thu, 30 Apr 2026 13:31:22 +0200 On x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a "WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d", from the VM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by "BUG: Bad rss-counter state"s, then later "BUG: Bad page state"s when reclaim gets to call shrink_huge_zero_folio_scan(). It's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and indeed, whereas pte_special() and pte_mkspecial() are subject to a dedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial() are subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on any 32-bit architecture. While the problem was exposed through commit d80a9cb1a64a ("mm/huge_memory: add and use normal_or_softleaf_folio_pmd()"), it was an oversight in commit af38538801c6 ("mm/memory: factor out common code from vm_normal_page_*()") and would result in other problems: * huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and numamaps as file-backed THP * folio_walk_start() returning the folio even without FW_ZEROPAGE set. Callers seem to tolerate that, though. ... and triggering the VM_WARN_ON_ONE(), although never reported so far. To fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider whether pmd_special/pud_special is actually implemented. Link: https://lore.kernel.org/20260430-pmd_special-v1-1-dbcbcfd72c20@kernel.org Fixes: af38538801c6 ("mm/memory: factor out common code from vm_normal_page_*()") Signed-off-by: David Hildenbrand (Arm) Reported-by: Hugh Dickins Closes: https://lore.kernel.org/r/74a75b59-2e13-3985-ee99-d5521f39df2a@google.com Reported-by: Bibo Mao Closes: https://lore.kernel.org/r/20260430041121.2839350-1-maobibo@loongson.cn Debugged-by: Hugh Dickins Reviewed-by: Lance Yang Tested-by: Bibo Mao Reviewed-by: Baolin Wang Reviewed-by: Oscar Salvador Reviewed-by: Lorenzo Stoakes Cc: Liam R. Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton --- mm/memory.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) --- a/mm/memory.c~mm-fix-__vm_normal_page-to-handle-missing-support-for-pmd_special-pud_special +++ a/mm/memory.c @@ -612,6 +612,21 @@ static void print_bad_page_map(struct vm dump_stack(); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); } + +static inline bool pgtable_level_has_pxx_special(enum pgtable_level level) +{ + switch (level) { + case PGTABLE_LEVEL_PTE: + return IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL); + case PGTABLE_LEVEL_PMD: + return IS_ENABLED(CONFIG_ARCH_SUPPORTS_PMD_PFNMAP); + case PGTABLE_LEVEL_PUD: + return IS_ENABLED(CONFIG_ARCH_SUPPORTS_PUD_PFNMAP); + default: + return false; + } +} + #define print_bad_pte(vma, addr, pte, page) \ print_bad_page_map(vma, addr, pte_val(pte), page, PGTABLE_LEVEL_PTE) @@ -684,7 +699,7 @@ static inline struct page *__vm_normal_p unsigned long addr, unsigned long pfn, bool special, unsigned long long entry, enum pgtable_level level) { - if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { + if (pgtable_level_has_pxx_special(level)) { if (unlikely(special)) { #ifdef CONFIG_FIND_NORMAL_PAGE if (vma->vm_ops && vma->vm_ops->find_normal_page) @@ -699,8 +714,9 @@ static inline struct page *__vm_normal_p return NULL; } /* - * With CONFIG_ARCH_HAS_PTE_SPECIAL, any special page table - * mappings (incl. shared zero folios) are marked accordingly. + * With working pte_special()/pmd_special()..., any special page + * table mappings (incl. shared zero folios) are marked + * accordingly. */ } else { if (unlikely(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))) { _ Patches currently in -mm which might be from david@kernel.org are sh-use-folio_mapped-instead-of-page_mapped-in-sh4_flush_cache_page.patch bpf-arena-use-page_ref_count-instead-of-page_mapped-in-arena_free_pages.patch mm-remove-page_mapped.patch sparc-mm-remove-register_page_bootmem_info.patch mm-bootmem_info-drop-initialization-of-page-lru.patch mm-bootmem_info-stop-using-pg_private.patch mm-bootmem_info-remove-call-to-kmemleak_free_part_phys.patch mm-bootmem_info-stop-marking-the-pgdat-as-node_info.patch mm-bootmem_info-stop-marking-mem_section_usage-as-mix_section_info.patch s390-mm-use-free_reserved_page-in-vmem_free_pages.patch powerpc-mm-remove-config_have_bootmem_info_node.patch