From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35114 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752100AbeBBRB0 (ORCPT ); Fri, 2 Feb 2018 12:01:26 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yisheng Xie , Catalin Marinas , Michal Hocko , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.4 47/67] kmemleak: add scheduling point to kmemleak_scan() Date: Fri, 2 Feb 2018 17:58:16 +0100 Message-Id: <20180202140820.602701736@linuxfoundation.org> In-Reply-To: <20180202140815.091718203@linuxfoundation.org> References: <20180202140815.091718203@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yisheng Xie [ Upstream commit bde5f6bc68db51128f875a756e9082a6c6ff7b4c ] kmemleak_scan() will scan struct page for each node and it can be really large and resulting in a soft lockup. We have seen a soft lockup when do scan while compile kernel: watchdog: BUG: soft lockup - CPU#53 stuck for 22s! [bash:10287] [...] Call Trace: kmemleak_scan+0x21a/0x4c0 kmemleak_write+0x312/0x350 full_proxy_write+0x5a/0xa0 __vfs_write+0x33/0x150 vfs_write+0xad/0x1a0 SyS_write+0x52/0xc0 do_syscall_64+0x61/0x1a0 entry_SYSCALL64_slow_path+0x25/0x25 Fix this by adding cond_resched every MAX_SCAN_SIZE. Link: http://lkml.kernel.org/r/1511439788-20099-1-git-send-email-xieyisheng1@huawei.com Signed-off-by: Yisheng Xie Suggested-by: Catalin Marinas Acked-by: Catalin Marinas Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- mm/kmemleak.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1394,6 +1394,8 @@ static void kmemleak_scan(void) if (page_count(page) == 0) continue; scan_block(page, page + 1, NULL); + if (!(pfn % (MAX_SCAN_SIZE / sizeof(*page)))) + cond_resched(); } } put_online_mems();