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 605F72036FE; Fri, 1 Aug 2025 21:11:35 +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=1754082695; cv=none; b=Neh4UJ5D3FeCU/42H0PpxzhJRllVGLja7bAVgi19josKsXu6wu5FToV87gwJisRWfpMxK+C8u6fSNC+QgqY7JnErbNzJs3NHO4UHK6J5xEa5ljqAXv2N+lQRyK1oxFxWXXz4UrEbSnh2yL3qbD8gv2ZBUhgF4UsNBDnkY8bkxvs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754082695; c=relaxed/simple; bh=3yxcwkca5yKSX/TeLduikPqF5CqYYiXa99FX6vfUtSg=; h=Date:To:From:Subject:Message-Id; b=OHenDu6HeTmYOZuazFkLXP6dg7FNkE6iVN1uI6nO+ZjnKZuHyevHvtgW4Q9Og/7w9NhwLFPucNtAMPwzH3v9REYq0rEZH557WDn5TEYogwvsNDG9XuJC4y5Hfiw32ty7+B63xQaRL1PFtallcYCiUqRwlc8fBSlyfSbiFvU+k5k= 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=uLoBCnHM; 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="uLoBCnHM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9A4AC4CEE7; Fri, 1 Aug 2025 21:11:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1754082694; bh=3yxcwkca5yKSX/TeLduikPqF5CqYYiXa99FX6vfUtSg=; h=Date:To:From:Subject:From; b=uLoBCnHMQS4Cyts92bSw5IiUcxWWd85Gk9p/S/Wa4J+NYDDJzjb4EZNpLTE+xViFl t2JgRzEYiuFjeJI4UzjMNNaXfMAQr92ysv2KH0a+XWzh4DGM23YkTjBQA2DmJrBH7C YawcsFGgi1RAsXiGdVLUQeksz+iK8kjFc6450xsE= Date: Fri, 01 Aug 2025 14:11:34 -0700 To: mm-commits@vger.kernel.org,surenb@google.com,stable@vger.kernel.org,david@redhat.com,aarcange@redhat.com,sashal@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte.patch added to mm-hotfixes-unstable branch Message-Id: <20250801211134.D9A4AC4CEE7@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Sasha Levin Subject: mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE Date: Thu, 31 Jul 2025 10:44:31 -0400 With CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using kmap_local_page(), which requires unmapping in Last-In-First-Out order. The current code maps dst_pte first, then src_pte, but unmaps them in the same order (dst_pte, src_pte), violating the LIFO requirement. This causes the warning in kunmap_local_indexed(): WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c addr \!= __fix_to_virt(FIX_KMAP_BEGIN + idx) Fix this by reversing the unmap order to respect LIFO ordering. This issue follows the same pattern as similar fixes: - commit eca6828403b8 ("crypto: skcipher - fix mismatch between mapping and unmapping order") - commit 8cf57c6df818 ("nilfs2: eliminate staggered calls to kunmap in nilfs_rename") Both of which addressed the same fundamental requirement that kmap_local operations must follow LIFO ordering. Link: https://lkml.kernel.org/r/20250731144431.773923-1-sashal@kernel.org Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Signed-off-by: Sasha Levin Acked-by: David Hildenbrand Reviewed-by: Suren Baghdasaryan Cc: Andrea Arcangeli Cc: Signed-off-by: Andrew Morton --- mm/userfaultfd.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/mm/userfaultfd.c~mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte +++ a/mm/userfaultfd.c @@ -1453,10 +1453,15 @@ out: folio_unlock(src_folio); folio_put(src_folio); } - if (dst_pte) - pte_unmap(dst_pte); + /* + * Unmap in reverse order (LIFO) to maintain proper kmap_local + * index ordering when CONFIG_HIGHPTE is enabled. We mapped dst_pte + * first, then src_pte, so we must unmap src_pte first, then dst_pte. + */ if (src_pte) pte_unmap(src_pte); + if (dst_pte) + pte_unmap(dst_pte); mmu_notifier_invalidate_range_end(&range); if (si) put_swap_device(si); _ Patches currently in -mm which might be from sashal@kernel.org are mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte.patch