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 26CC622F767; Sat, 17 Oct 2026 17:28:25 +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=1792258107; cv=none; b=jeK3a2VFwuKCc1rLcSGGLpAxu2DDeMXy14GExtuUJPGDgJf2M1khbQ3R0xB2wExPmXPaFAFtTcJBDcV8LYV4CnNFs9FABHp+96hNlGMhYLoQsQ3a3TGvz4kpA7gukGDJh13kJGfoE4/yNgwUbnhm6OB0m9e05bzNqNSR7Q3AOyg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792258107; c=relaxed/simple; bh=oXRN4zif6CRVCfdXyuhUbpH6ZWaDYAdltr5x1NfVEts=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Uu1SJutFTEkc6zt91I2y2WxjzMN5I3HgZREimPOQ6ijrWHduxMU/eTe55A8y5OfoxrGwT8sw7VRZHHY7CF/i347ElMQVUiItVRjrRwMqGOZEFX4m2M+nGLVOw4wixKyjtpaadi6uBhRz4jAPLQTtFbHr4JvBAYIHRHTD+bbOuyI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VrO0X+OK; 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="VrO0X+OK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AA961F000C4; Sat, 17 Oct 2026 17:28:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792258105; bh=bkt7i6Lwe3zsaxd4IySKfgUaMzoHihb1q1UIhJaC8vA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VrO0X+OK2RV6QP0ZrKb6QtiRAcTRrw9HhPrhAckaT1wzi8bFYBOVEwFTfeZkwEKzg A4y5Zh1AKMao+Gfroav2O8hSBvufvmITxVmGty06dDD1x78xAN5B+iiWuZ6I7LNfQf PR4MATr7NU2+1iz9awOq7k7a7GCLRAf1swoWNkJE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jinjiang Tu , David Hildenbrand , Andrei Vagin , Andrii Nakryiko , Baolin Wang , Brahmajit Das , Catalin Marinas , Christophe Leroy , David Rientjes , Dev Jain , Hugh Dickins , Joern Engel , Kefeng Wang , Lorenzo Stoakes , Michal Hocko , Ryan Roberts , Thiago Jung Bauermann , Andrew Morton , Sasha Levin Subject: [PATCH 6.6 0774/1674] mm/smaps: fix race between smaps_hugetlb_range and migration Date: Sat, 17 Oct 2026 17:50:46 +0200 Message-ID: <20261017160450.971643828@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160431.119607952@linuxfoundation.org> References: <20261017160431.119607952@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jinjiang Tu [ Upstream commit 45d19b4b6c2d422771c29b83462d84afcbb33f01 ] smaps_hugetlb_range() handles the pte without holdling ptl, and may be concurrenct with migration, leaing to BUG_ON in pfn_swap_entry_to_page(). The race is as follows. smaps_hugetlb_range migrate_pages huge_ptep_get remove_migration_ptes folio_unlock pfn_swap_entry_folio BUG_ON To fix it, hold ptl lock in smaps_hugetlb_range(). Link: https://lkml.kernel.org/r/20250724090958.455887-1-tujinjiang@huawei.com Link: https://lkml.kernel.org/r/20250724090958.455887-2-tujinjiang@huawei.com Fixes: 25ee01a2fca0 ("mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps") Signed-off-by: Jinjiang Tu Acked-by: David Hildenbrand Cc: Andrei Vagin Cc: Andrii Nakryiko Cc: Baolin Wang Cc: Brahmajit Das Cc: Catalin Marinas Cc: Christophe Leroy Cc: David Rientjes Cc: Dev Jain Cc: Hugh Dickins Cc: Joern Engel Cc: Kefeng Wang Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Ryan Roberts Cc: Thiago Jung Bauermann Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- fs/proc/task_mmu.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index ac7e356cacebc..5c6214d8e0937 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -724,8 +724,11 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask, struct mem_size_stats *mss = walk->private; struct vm_area_struct *vma = walk->vma; struct page *page = NULL; - pte_t ptent = ptep_get(pte); + spinlock_t *ptl; + pte_t ptent; + ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte); + ptent = ptep_get(pte); if (pte_present(ptent)) { page = vm_normal_page(vma, addr, ptent); } else if (is_swap_pte(ptent)) { @@ -740,6 +743,7 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask, else mss->private_hugetlb += huge_page_size(hstate_vma(vma)); } + spin_unlock(ptl); return 0; } #else -- 2.53.0