From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7C8B9409DE0; Thu, 28 May 2026 19:54:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779998050; cv=none; b=kbTJbsRPUPT49UDlRAUlFw93Fy2hr/TgoMs+WbaMOwoIlVu6Dz6avcx34hIAVzLagyeVRW8NGihZyPPxu168P5d6GcyuU66a4VWeEyorKcCwcAila0the00vl++Po3jYozhhPGi9pow9sSEKsJ7iGudZpGwyrmKsgJyHEmabOoo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779998050; c=relaxed/simple; bh=TJBYtCBK8Tx5Mumv7vXzqWvO/bRwv3sYY7rbAN/FZRU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NauT1ExajuPesWo5ABI9WT09QDeZB2JOCr6Rq3zdX8IfzhjC2wYwlQO0WFws7PAgke4MwvP4e+r4j3zjnZZlz+cAaVo25bvVuWj3aTMDM9OE1ZjYYA7FCxqV1yN1iJkfNPHgLHvlQFn0RizTr89t6qZH8e4ch7tDF+3QlsKlRxI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RTRnnEU/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RTRnnEU/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 841741F00A3A; Thu, 28 May 2026 19:54:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779998049; bh=75hrHeJGhdskIk1BP1nKaEPcRAuYmofK6lB8sFG4JtM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RTRnnEU/w/G2fmlDO72zsenHyYSopVsXjBI2csw395lWcKBd0rZM5PjzlN4iiRU4Q V0X+DGmCl+SxLE99NTe5Mo6zskvPMC1kdEjGunMUaOOedbL/mRYRCkzLvlSK/+//sJ RYYJUY/yBLaGryLv1YswJNKqxSrhw0C9/SKzt/CM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "David Hildenbrand (Arm)" , Hugh Dickins , Bibo Mao , Lance Yang , Baolin Wang , Oscar Salvador , Lorenzo Stoakes , "Liam R. Howlett" , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , Andrew Morton Subject: [PATCH 7.0 034/461] mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special() Date: Thu, 28 May 2026 21:42:43 +0200 Message-ID: <20260528194647.883513551@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194646.819809818@linuxfoundation.org> References: <20260528194646.819809818@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Hildenbrand (Arm) commit c0c6ccd9828c3a1950623b546fa57292a77b5c73 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- mm/memory.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) --- a/mm/memory.c +++ b/mm/memory.c @@ -625,6 +625,21 @@ 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) @@ -697,7 +712,7 @@ 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) @@ -712,8 +727,9 @@ 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))) {