From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794455279; b=eQaCaR++Igf4U5YOwfk3GQWOi9YVIJgjisD1mTqecOOkiAlbxeCHxppf7tn2MAIUUAJT Yx17QPGoxWT2t6brVkRKmp6lIfytSwBAOm7E5okLban2w09gyoVm3eZX5fpAsz7Jm+fnF 5g6YE7Q3F8Xb6hfRFkrObzflS+vn9xstZZ9uI5NCFTeO1POxhHKd5Dj5XHMYHcQyCk6lQ S4PvnEZ0oBD4GOHhT3chIFWzSjUDczc3rW0urekWFC6TuQ4x2CEdkAkHCJYQDKV8m4xQ8 Lp+tXXhyKipHuVlz0NGTL85Y7gJYLTtuws+LWWViS2vTxYjimg6vqlIk1c4y1301kkw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794455279; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=ShFOLd8JJMDMfRs8kbJ2xRTG7jrnMeWavY86zBMAdAM=; b=BS2eYQgbO+EtdPj+4dyTKckoRyHRaG5u5U4C6cDYAlpynIZknWznCLEGeTX5aL0T9nQc sVQpcU6kpue+iWXUqFKFua9fZYUh93EDVUkyaUcvSlUwNexbZYEZATQqnypM4urN87DIb gUSjbqz/vZmM4/kQv/F8EeAnyapN6eX66ha6HPb3umtNDCQsmTxPGetfN5WWVgsopvILG jI6N9svGFtCjqN5WOp/EnBh9jeMd3tEhDGpiSinap7iKGCMSLMpG1HV5Bay1vBLch7AQr xqqRK3n5WJI1svpGxspNMbY2eIYrCZE2eHDPtX9iGxxvUK6ckBPB/RW8znFqvK+bWvg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Wv7FGhcN; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D87D606A31C for ; Thu, 12 Nov 2026 03:47:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Wv7FGhcN Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80A961F00A06; Thu, 12 Nov 2026 03:47:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794455279; bh=ShFOLd8JJMDMfRs8kbJ2xRTG7jrnMeWavY86zBMAdAM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Wv7FGhcNmyREQ/mIOM4iNV6zoeGRsQ6JXamESMQ/uS/CLhBzfMJJ6wZGQj17D938W UdnjRSvrUEm9qx3AXMHaGs4EpOLPsJxXCELzDOo6EW5ZqAnKVmfcI90r6ic6QvtSHJ RBuvTFYCH++fbHJ8C0cvdMCpA0+qi0Jq0iUYY9bGWLx2PE0pS5PCB/NGDSBWRrYU2L 8/MTV1cJ7OkvkfP+P6tM9Glac/+1rb9yuRihcmMBAH0ckP9Ly6qG9t8Dal4Opfd9CM shprfn5FBOE31offGtHnpV/H9qe2vnAV6h3Y6p65iaEdnM5bGyWnrPtGDtEaP1keCI bf5CRgPUOhFyA== From: Sasha Levin To: stable@vger.kernel.org Cc: "Lorenzo Stoakes (ARM)" , Andrew Morton , Luiz Capitulino , "Vlastimil Babka (SUSE)" , Pedro Falcato , "Liam R. Howlett" , Jann Horn , =?UTF-8?q?Jakub=20Mat=C4=9Bna?= , Sasha Levin Subject: [PATCH 6.6.y] mm/vma: fix expansion of VMA_MIXEDMAP_BIT VMAs Date: Wed, 11 Nov 2026 22:47:57 -0500 Message-ID: <20261112034659.1574521-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109201217-failed-6.6-8146c6478224@kernel.org> References: <20261109201217-failed-6.6-8146c6478224@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: "Lorenzo Stoakes (ARM)" [ Upstream commit 8146c6478224d8f6395c6b08a19c344a56d79867 ] Commit ca3d76b0aa80 ("mm: add merging after mremap resize") combined merging with expansion of mremap()'d VMAs, however it also unintentionally disallowed the expansion of unmergeable VMAs. Previously it was possible to expand a mixed mapping which mremap() had already ensured was a legal expansion. This is clearly seen in the mremap() logic, as it checks vma_is_fixed_mapping() to determine legality of an expansion rather than vma_can_merge(). Additionally, copy_vma() allows for a failed merge to result in a new VMA being instantiated if MREMAP_MAYMOVE is specified. However, this is not attempted, as a failure in vma_merge_extend() is assumed to be an -ENOMEM failure. Since vma_merge_extend() is used exclusively by mremap() to perform a merge and/or expansion, resolve the issue by invoking vma_expand() for unmergeable VMAs there. Explicitly assert that the VMA is both non-fixed and a mixed mapping. This provides double insurance against broken changes in future. Note that khugepaged_enter_vma() (which vma_merge_new_range() runs) is redundant in this case, as a mixed mapping is not subject to khugepaged. Also update the VMA userland tests to add a required predicate. Link: https://lore.kernel.org/20261023-vma-expansion-fix-v1-1-6142baf1f46b@kernel.org Fixes: ca3d76b0aa80 ("mm: add merging after mremap resize") Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton Reported-by: Luiz Capitulino Closes: https://lore.kernel.org/all/20261023023106.515365-1-luizcap@redhat.com/ Acked-by: Vlastimil Babka (SUSE) Reviewed-by: Pedro Falcato Cc: Liam R. Howlett Cc: Jann Horn Cc: Jakub Matěna Cc: [ sashal: Adapted vma_merge_extend() changes to the inline mremap() implementation using the older vma_expand() interface. ] Signed-off-by: Sasha Levin --- mm/mremap.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index 0739a31b54eed..a37bcfda29261 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1120,10 +1120,21 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, * the next vma if it becomes adjacent to the expanded * vma and otherwise compatible. */ - vma = vma_merge(&vmi, mm, vma, extension_start, - extension_end, vma->vm_flags, vma->anon_vma, - vma->vm_file, extension_pgoff, vma_policy(vma), - vma->vm_userfaultfd_ctx, anon_vma_name(vma)); + if (!(vma->vm_flags & (VM_PFNMAP | VM_DONTEXPAND | + VM_MIXEDMAP))) { + vma = vma_merge(&vmi, mm, vma, extension_start, + extension_end, vma->vm_flags, vma->anon_vma, + vma->vm_file, extension_pgoff, vma_policy(vma), + vma->vm_userfaultfd_ctx, anon_vma_name(vma)); + } else { + /* Mixed mappings are permitted to be expanded, not merged. */ + VM_WARN_ON_ONCE(vma->vm_flags & (VM_PFNMAP | VM_DONTEXPAND)); + VM_WARN_ON_ONCE(!(vma->vm_flags & VM_MIXEDMAP)); + vma_prev(&vmi); /* Reposition to start of VMA. */ + if (vma_expand(&vmi, vma, vma->vm_start, + extension_end, vma->vm_pgoff, NULL)) + vma = NULL; + } if (!vma) { vm_unacct_memory(pages); ret = -ENOMEM; -- 2.53.0