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 691CF275112; Mon, 17 Nov 2025 16:02:36 +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=1763395356; cv=none; b=jSDtHw/hdbkl6T7c5Dc6HUHPxnEZrpa2Cj5uMFUeoDBJ7EvP2sRN5HgjGc9803MPawbwjcKN8M7rBCxq2423TWWt663Oa/hR2aJHWRNtxWV8aoTx0W+QiOcrj7Y3m2jjLoLi+efgrSQm4dxxayRsYkizS/t5Nlmudb+Jclcn6k4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763395356; c=relaxed/simple; bh=Jkvmu4Q+7pA4zSpi9OFk7bJIcNsGVtBgomWoRKHdM8A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BiOgSsI2eqbl74C4bSuy/TPaZTkMRXo/4xY7Z8GI1w2F788Cb2YwXBG61+3gwQ+Hxxo+C4JBctF9ZT0nW16cy9taYfEegJ3hkilbIqEjJES7qjcaFTpZfP46+m86Ah20yV7O0DopogY9DbvwpPZfmi8CyOQUl960R1kn4USabnI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HRN9ah8J; 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="HRN9ah8J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B502C113D0; Mon, 17 Nov 2025 16:02:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763395356; bh=Jkvmu4Q+7pA4zSpi9OFk7bJIcNsGVtBgomWoRKHdM8A=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=HRN9ah8J0i3UDd6igt5wSrmwF/x03+POYYvvNYin0MqGa7LWADEznY83zaPtwUDRs ScnopSM94D7deN4mSE1KVPZzP934yzIg+LXrta6j2nrouhyFH8av2u/a0qRtna5hcS 25x8yxJl/uczThIH67MpaOJdwwfBJbiJeFru+UKaP8JGt3PlkKh4hRQ652Cb9cKrPs E2r8M8rZOR3hxKd5EgzdfshSFNvH8gXZCEuOUMYRte20uezKAeZzYovSXDLoq6Ifp0 HcHsxX7esNJloZeJSP6iRggCBQFjamV20khnzZ5sVK1x/n1QLcw8tOqAiGCv274hvX 8cuBHc5tDmKWQ== Message-ID: Date: Mon, 17 Nov 2025 17:02:24 +0100 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC mm v6] mm: introduce a new page type for page pool in page type To: Byungchul Park , linux-mm@kvack.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, almasrymina@google.com, toke@redhat.com, asml.silence@gmail.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com, dtatulea@nvidia.com References: <20251117052041.52143-1-byungchul@sk.com> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: <20251117052041.52143-1-byungchul@sk.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 17/11/2025 06.20, Byungchul Park wrote: > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 600d9e981c23..01dd14123065 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1041,7 +1041,6 @@ static inline bool page_expected_state(struct page *page, > #ifdef CONFIG_MEMCG > page->memcg_data | > #endif > - page_pool_page_is_pp(page) | > (page->flags.f & check_flags))) > return false; > > @@ -1068,8 +1067,6 @@ static const char *page_bad_reason(struct page *page, unsigned long flags) > if (unlikely(page->memcg_data)) > bad_reason = "page still charged to cgroup"; > #endif > - if (unlikely(page_pool_page_is_pp(page))) > - bad_reason = "page_pool leak"; > return bad_reason; > } This code have helped us catch leaks in the past. When this happens the result is that the page is marked as a bad page. > > @@ -1378,9 +1375,12 @@ __always_inline bool free_pages_prepare(struct page *page, > mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); > folio->mapping = NULL; > } > - if (unlikely(page_has_type(page))) > + if (unlikely(page_has_type(page))) { > + /* networking expects to clear its page type before releasing */ > + WARN_ON_ONCE(PageNetpp(page)); > /* Reset the page_type (which overlays _mapcount) */ > page->page_type = UINT_MAX; > + } > > if (is_check_pages_enabled()) { > if (free_page_is_bad(page)) What happens to the page? ... when it gets marked with: page->page_type = UINT_MAX Will it get freed and allowed to be used by others? - if so it can result in other hard-to-catch bugs --Jesper