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 ABEB7388E7C for ; Tue, 3 Mar 2026 09:04:30 +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=1772528670; cv=none; b=bn+6Xvj+ys454D1sHQHfiJR2dwzHFQZoWpOk0XcDhLxWPslwVSdSFwXpLmRmOlSiXWeZH7yVMH+bmoLeHU2btYA6DEq/ef+RvbX4L8eZs/ouQj4cTnO0b1z4zWuriVZAhMg3sZbdODPRxLRg9vl1EZfqBoPiSHCViVgyXBy+c1Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772528670; c=relaxed/simple; bh=pcRg7UWy0oARLBPCzhsxNcvTwx5WBbNiYe8TNPnBms8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HdgD4r6nDpYEf5Y0KKtIH/tNX2ehn+4nTYhfVYemC1PPHM0XILPDyBG3Sm9m2xZXdp+u+eCi08BWuv1gh6NdHPaW3dR02CUSYA/jM50KdLmwOjDwg1lgv/1Kt6rGvWnucb/r/lOUxvkV6TPiLrcb1bRr0KChs2Hg81wHDLf1zig= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bwIg7by1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bwIg7by1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF6CBC116C6; Tue, 3 Mar 2026 09:04:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772528670; bh=pcRg7UWy0oARLBPCzhsxNcvTwx5WBbNiYe8TNPnBms8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=bwIg7by14/5Ml7GW5fG35Fybc0TWws4oWZAyqe1+hYdj4ZFel58Ezue5rsG8gjtAC Yg6gNAhYGp2wPP41LGs3qtEBF/Vk4AvoLjtLfxWmrE4gTF5kA9r/c6K3YxArzWAQrL BxxSdp9ycAwcg1Qu7kwPB0f9yLdLy4t8CnqCepfaHToGgZAD51vpW0ekyCw2QANT3+ rybJCFWvfrIPw52F/oB1oSnhR+HsyAdjPe77nDzKwIkW9QkEn9IZH7eTaRf+WWxujU 7x2pOm7B3QudTSqhVH5AB+Ed/bkj4rpTvlQ45FdazcS0AvKpf4q1pLg7AOdePTHnlA 5CF0w2qRGr05Q== Message-ID: Date: Tue, 3 Mar 2026 10:04:26 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [BUG] mm/mempolicy: possible double-unlock in migrate_to_node() on 6.6 To: Matthew Wilcox , "liying3@sungrowpower.com" Cc: akpm , linux-mm , linux-kernel , victor7q , Greg Kroah-Hartman References: <2026030310525141773825@sungrowpower.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/3/26 05:15, Matthew Wilcox wrote: > On Tue, Mar 03, 2026 at 10:52:51AM +0800, liying3@sungrowpower.com wrote: >> Hi Andrew, >> >> I found that a fix is required for this submission in branch 6.6. >> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a13b2b9b0b0b04612c7d81e3b3dfb485c5f7abc3 > > Agreed, although your email should more properly have been directed to > David and possibly Greg. Are you going to submit a patch to fix this, > or do you prefer that somebody else does it? > >> Regarding the difference between branches 6.6 and 6.12, in branch 6.6, mmap_read_lock() and mmap_read_unlock() are called outside the migrate_to_node() function. >> Therefore, mmap_read_unlock(mm) should not be invoked inside migrate_to_node(); otherwise, it would result in a double unlock of the mm. >> diff --git a/mm/mempolicy.c b/mm/mempolicy.c >> index 54f1b78d1b2c0f..94c74c594d102a 100644 >> --- a/mm/mempolicy.c >> +++ b/mm/mempolicy.c >> @@ -1071,6 +1071,10 @@ static long migrate_to_node(struct mm_struct *mm, int source, int dest, >> VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))); >> vma = find_vma(mm, 0); >> + if (unlikely(!vma)) { >> + mmap_read_unlock(mm); // this line should be deleted >> + return 0; >> + } Right, that unlock must go. Let me know if I should prepare a fix. -- Cheers, David