From patchwork Tue May 23 14:52:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 13252480 X-Patchwork-Delegate: kuba@kernel.org Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 1978B1F17A for ; Tue, 23 May 2023 14:53:03 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6770FA for ; Tue, 23 May 2023 07:53:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684853581; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0VBtvZeRIDwJBsf1UEDSI5VydF2ePAZSTRJieedCE2w=; b=IBn7Cxe36nbymCfb2hiITfYvTyEnrPVkNVRRG3/sM1H5/LOz6XJ3/bMStnbfTE4FAhq1Hh UAZbtUYUHuWRefB1+Nfn5zFnkbgGBcLdT/oCaVFJSbWCh+zxcUerla6h/MxcS4m9IrqG9T 67y4H5ll9XWEcR8xlCp13G16L7PYQts= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-630-F7ED3jOaNYOIEIWeDgZB8w-1; Tue, 23 May 2023 10:52:56 -0400 X-MC-Unique: F7ED3jOaNYOIEIWeDgZB8w-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8BAEC8039BE; Tue, 23 May 2023 14:52:54 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.45.242.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 43415400F49; Tue, 23 May 2023 14:52:54 +0000 (UTC) Received: from [10.1.1.1] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 503A1307372E8; Tue, 23 May 2023 16:52:53 +0200 (CEST) Subject: [PATCH RFC net-next/mm V4 1/2] mm/page_pool: catch page_pool memory leaks From: Jesper Dangaard Brouer To: Ilias Apalodimas , netdev@vger.kernel.org, Eric Dumazet , linux-mm@kvack.org, Mel Gorman Cc: Jesper Dangaard Brouer , lorenzo@kernel.org, =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , linyunsheng@huawei.com, bpf@vger.kernel.org, "David S. Miller" , Jakub Kicinski , Paolo Abeni , Andrew Morton , willy@infradead.org Date: Tue, 23 May 2023 16:52:53 +0200 Message-ID: <168485357325.2849279.485978688281828101.stgit@firesoul> In-Reply-To: <168485351546.2849279.13771638045665633339.stgit@firesoul> References: <168485351546.2849279.13771638045665633339.stgit@firesoul> User-Agent: StGit/1.4 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC Pages belonging to a page_pool (PP) instance must be freed through the PP APIs in-order to correctly release any DMA mappings and release refcnt on the DMA device when freeing PP instance. When PP release a page (page_pool_release_page) the page->pp_magic value is cleared. This patch detect a leaked PP page in free_page_is_bad() via unexpected state of page->pp_magic value being PP_SIGNATURE. We choose to report and treat it as a bad page. It would be possible to release the page via returning it to the PP instance as the page->pp pointer is likely still valid. Notice this code is only activated when either compiled with CONFIG_DEBUG_VM or boot cmdline debug_pagealloc=on, and CONFIG_PAGE_POOL. Reduced example output of leak with PP_SIGNATURE = dead000000000040: BUG: Bad page state in process swapper/0 pfn:110bbf page:000000005bc8cfb8 refcount:0 mapcount:0 mapping:0000000000000000 index:0x110bbf000 pfn:0x110bbf flags: 0x2fffff80000000(node=0|zone=2|lastcpupid=0x1fffff) raw: 002fffff80000000 dead000000000040 ffff888117255000 0000000000000000 raw: 0000000110bbf000 000000000000003e 00000000ffffffff 0000000000000000 page dumped because: page_pool leak [...] Signed-off-by: Jesper Dangaard Brouer --- mm/page_alloc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 47421bedc12b..e6b996da39d4 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1085,6 +1085,9 @@ static inline bool page_expected_state(struct page *page, page_ref_count(page) | #ifdef CONFIG_MEMCG page->memcg_data | +#endif +#ifdef CONFIG_PAGE_POOL + ((page->pp_magic & ~0x3UL) == PP_SIGNATURE) | #endif (page->flags & check_flags))) return false; @@ -1111,6 +1114,10 @@ static const char *page_bad_reason(struct page *page, unsigned long flags) #ifdef CONFIG_MEMCG if (unlikely(page->memcg_data)) bad_reason = "page still charged to cgroup"; +#endif +#ifdef CONFIG_PAGE_POOL + if (unlikely((page->pp_magic & ~0x3UL) == PP_SIGNATURE)) + bad_reason = "page_pool leak"; #endif return bad_reason; }