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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=X4SIFBEx; 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 66CE1606A324 for ; Mon, 2 Nov 2026 09:11:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=X4SIFBEx Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12B221F000C1; Mon, 2 Nov 2026 09:11:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793610666; bh=D5RkqP2tY/U34SmqxIrtmZ8h9C95VS8eUS3H2JGyIcc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=X4SIFBEx0PSNmylZuL+3YdIyiZli5R/xegiTYNYEIN2tDTbZEQEiopQkKOjGCJCoI GHb0fgaDRJbfVeeIaVcbqr0yotGy/O1omVb7TM70lmfzREiDUf26bzQUzRZ/vKTSUD IdCQkyXGVYzqbgSGMRFqn1LDUdajA6N6TThscDq+R6xLXFNrSBMDp3f9HdrwUmGV8p 1j1WnUfsiDHFLjEhIx9keqVwzBbRfOZMzBKBtceQWjdNX7yrAFjKfyaXiQgQT7mXNL LZul7GydUiVIn7ELkV6ENFNfGY8oO98MbQqB9Y8y1Twh7Cx+oTy/zHbEDrJL/7YwHG g5uLDONS4fNXA== Message-ID: <5d79db66-2195-4f8d-a721-e1756bc6ead0@kernel.org> Date: Mon, 2 Nov 2026 10:11:01 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/page_alloc: release isolated freepages on compound range mismatch To: Zhenghui Hao , akpm@linux-foundation.org Cc: vbabka@kernel.org, surenb@google.com, mhocko@suse.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: 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 11/2/26 10:06, Zhenghui Hao wrote: > alloc_contig_frozen_range_noprof() isolates [outer_start, outer_end) > before checking whether a __GFP_COMP request exactly matches the > allocated range. If it does not, the function returns -EINVAL without > releasing cc.freepages, leaking the isolated pages. > > Call release_free_list() before returning -EINVAL, while the pageblock > is still isolated, matching the cleanup already used when > isolate_freepages_range() fails. > > Use WARN_ONCE() as well: the condition is reachable through the exported > API, and repeated invalid calls should not flood dmesg. > > Tested with an order-9 free pageblock and a one-page __GFP_COMP > subrange: > before: free_buddy=0, leaked=512/512 > after: free_buddy=1, leaked=0/512 How did you reproduce this? Using a hacky kernel module? > > Fixes: e98337d11bbdf ("mm/contig_alloc: support __GFP_COMP") I thought we discussed this in the past: if you are able to trigger the WARN something is messed up already. And indeed, same patch already here, SMH https://lore.kernel.org/linux-mm/20260629-free-pfn-on-alloc-contig-range-error-path-v1-1-496ff9ca22db@nvidia.com/ -- Cheers, David