From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC8F5C433FE for ; Mon, 7 Feb 2022 11:37:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359467AbiBGL2o (ORCPT ); Mon, 7 Feb 2022 06:28:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1383564AbiBGLW6 (ORCPT ); Mon, 7 Feb 2022 06:22:58 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B8CBC043181; Mon, 7 Feb 2022 03:22:57 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 34F6DB80EC3; Mon, 7 Feb 2022 11:22:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 612E2C004E1; Mon, 7 Feb 2022 11:22:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644232975; bh=cpJn+EIkjNPDv9SUqXa9/2HaFKcFbCOvxSlkiqMAxbU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1ejXNo88Zgswkt7UQmB7mEWOX63s2JJbrPlnWuGjb8mSfkQ90RjXiYZaoOGefWsDP DE+zGZJn9LAf9oMHw3qqwAZ41zlldQnPJedi1TsRI7sB5+zO9WDs0Kb3c3M5fbJnT6 2VlkAHoA274IzNIapruAcHBXRQjHvZurSPdmw7hk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lang Yu , David Hildenbrand , Catalin Marinas , Oscar Salvador , Andrew Morton , Linus Torvalds Subject: [PATCH 5.10 19/74] mm/kmemleak: avoid scanning potential huge holes Date: Mon, 7 Feb 2022 12:06:17 +0100 Message-Id: <20220207103757.867500990@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220207103757.232676988@linuxfoundation.org> References: <20220207103757.232676988@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Lang Yu commit c10a0f877fe007021d70f9cada240f42adc2b5db upstream. When using devm_request_free_mem_region() and devm_memremap_pages() to add ZONE_DEVICE memory, if requested free mem region's end pfn were huge(e.g., 0x400000000), the node_end_pfn() will be also huge (see move_pfn_range_to_zone()). Thus it creates a huge hole between node_start_pfn() and node_end_pfn(). We found on some AMD APUs, amdkfd requested such a free mem region and created a huge hole. In such a case, following code snippet was just doing busy test_bit() looping on the huge hole. for (pfn = start_pfn; pfn < end_pfn; pfn++) { struct page *page = pfn_to_online_page(pfn); if (!page) continue; ... } So we got a soft lockup: watchdog: BUG: soft lockup - CPU#6 stuck for 26s! [bash:1221] CPU: 6 PID: 1221 Comm: bash Not tainted 5.15.0-custom #1 RIP: 0010:pfn_to_online_page+0x5/0xd0 Call Trace: ? kmemleak_scan+0x16a/0x440 kmemleak_write+0x306/0x3a0 ? common_file_perm+0x72/0x170 full_proxy_write+0x5c/0x90 vfs_write+0xb9/0x260 ksys_write+0x67/0xe0 __x64_sys_write+0x1a/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae I did some tests with the patch. (1) amdgpu module unloaded before the patch: real 0m0.976s user 0m0.000s sys 0m0.968s after the patch: real 0m0.981s user 0m0.000s sys 0m0.973s (2) amdgpu module loaded before the patch: real 0m35.365s user 0m0.000s sys 0m35.354s after the patch: real 0m1.049s user 0m0.000s sys 0m1.042s Link: https://lkml.kernel.org/r/20211108140029.721144-1-lang.yu@amd.com Signed-off-by: Lang Yu Acked-by: David Hildenbrand Acked-by: Catalin Marinas Cc: Oscar Salvador Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/kmemleak.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1401,7 +1401,8 @@ static void kmemleak_scan(void) { unsigned long flags; struct kmemleak_object *object; - int i; + struct zone *zone; + int __maybe_unused i; int new_leaks = 0; jiffies_last_scan = jiffies; @@ -1441,9 +1442,9 @@ static void kmemleak_scan(void) * Struct page scanning for each node. */ get_online_mems(); - for_each_online_node(i) { - unsigned long start_pfn = node_start_pfn(i); - unsigned long end_pfn = node_end_pfn(i); + for_each_populated_zone(zone) { + unsigned long start_pfn = zone->zone_start_pfn; + unsigned long end_pfn = zone_end_pfn(zone); unsigned long pfn; for (pfn = start_pfn; pfn < end_pfn; pfn++) { @@ -1452,8 +1453,8 @@ static void kmemleak_scan(void) if (!page) continue; - /* only scan pages belonging to this node */ - if (page_to_nid(page) != i) + /* only scan pages belonging to this zone */ + if (page_zone(page) != zone) continue; /* only scan if page is in use */ if (page_count(page) == 0)