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 95B11C433EF for ; Tue, 1 Feb 2022 00:52:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230527AbiBAAwO (ORCPT ); Mon, 31 Jan 2022 19:52:14 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:36076 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231351AbiBAAwJ (ORCPT ); Mon, 31 Jan 2022 19:52:09 -0500 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 4D73DB82CA2; Tue, 1 Feb 2022 00:52:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C129CC340E8; Tue, 1 Feb 2022 00:52:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1643676727; bh=QOi8H3QAK1EPbB/Xm/Ov9s81bm+RTRA6MdtBDdjQxt4=; h=Date:To:From:Subject:From; b=HeaqmVmZgE1tfS8Mm9ZUwg2XcWpCNg1zzWWOk0Ot/5gIzFUfyxxX2/PGEG84oTKMI N3POAQd+D3sE/LYtcgD6C/2d5LgB404pYIXYP6SVY9TbMARSr+07oRsG89Km2Dt8j5 aCpw5GbFtrIgZWiBEFynI/gGwhIT8DqsUvxwZvEc= Received: by hp1 (sSMTP sendmail emulation); Mon, 31 Jan 2022 16:52:05 -0800 Date: Mon, 31 Jan 2022 16:52:05 -0800 To: mm-commits@vger.kernel.org, stable@vger.kernel.org, osalvador@suse.de, david@redhat.com, catalin.marinas@arm.com, lang.yu@amd.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-kmemleak-avoid-scanning-potential-huge-holes.patch added to -mm tree Message-Id: <20220201005205.C129CC340E8@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm/kmemleak: avoid scanning potential huge holes has been added to the -mm tree. Its filename is mm-kmemleak-avoid-scanning-potential-huge-holes.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-kmemleak-avoid-scanning-potential-huge-holes.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-kmemleak-avoid-scanning-potential-huge-holes.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Lang Yu Subject: mm/kmemleak: avoid scanning potential huge holes 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 --- mm/kmemleak.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/mm/kmemleak.c~mm-kmemleak-avoid-scanning-potential-huge-holes +++ a/mm/kmemleak.c @@ -1410,7 +1410,8 @@ 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; @@ -1450,9 +1451,9 @@ 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++) { @@ -1461,8 +1462,8 @@ 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) _ Patches currently in -mm which might be from lang.yu@amd.com are mm-kmemleak-avoid-scanning-potential-huge-holes.patch