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 0DED5321443; Mon, 18 Aug 2025 13:17:30 +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=1755523050; cv=none; b=QN/5+C1+rRljWRd9tXxAUl6Hy7/nExyzN/YN6KCxsZvWT8eZeI6dqlyuNIyOv/njomMAaV6/x53HL/Spe2nVp3pOVEp30lnxs4limBtB5yhIHGGwVMKxekySCyOoCmqWx0Nnxu+srRJhjidOqVdKp48IrEsWyy9wh6dga2flcAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755523050; c=relaxed/simple; bh=aT0h892pZlRAdcg0UFHniUZA67aCUJX6aR4Z99OVimo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XlMYquEwNc8lr7m9EAfZzPin/evlAJuu97/8xHmx1sciZgeXgGPIIVYTb2RTHP4iAddinIiLvq9Bdi77k4hz3VTF/rV+b45gfWyy3MWS9qynrIJInIfrU4X/Do9bCf5+HGojdLgp8ZaKbhAVbhEOYc2uiT3OQZcjknBy0iCMaEI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=U5iED7zR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="U5iED7zR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F7BDC4CEEB; Mon, 18 Aug 2025 13:17:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755523049; bh=aT0h892pZlRAdcg0UFHniUZA67aCUJX6aR4Z99OVimo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U5iED7zRB7VZ1F6UmW9HcdMnXjDBVg6ndVqNxmt0sbdqDjlUIC5jTuqi68emWZN/h jHhESS+W0ztZ5Ib2g739WovPOX+klbf62rWFChDSds2McO8gl+vdKiQcG6QQAkjGYC I/bC0zAZ4j87IDJNv5lmQ8Y3hFoINj0fvHxTvMcw= 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 6.15 056/515] mm/smaps: fix race between smaps_hugetlb_range and migration Date: Mon, 18 Aug 2025 14:40:42 +0200 Message-ID: <20250818124500.575184338@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124458.334548733@linuxfoundation.org> References: <20250818124458.334548733@linuxfoundation.org> User-Agent: quilt/0.68 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 6.15-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 e57e323817e7..3b8eaa7722c8 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1020,10 +1020,13 @@ 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; - pte_t ptent = huge_ptep_get(walk->mm, addr, pte); struct folio *folio = NULL; bool present = false; + spinlock_t *ptl; + pte_t ptent; + ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte); + ptent = huge_ptep_get(walk->mm, addr, pte); if (pte_present(ptent)) { folio = page_folio(pte_page(ptent)); present = true; @@ -1042,6 +1045,7 @@ 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 -- 2.50.1