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 X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29490C2B9F4 for ; Mon, 14 Jun 2021 13:23:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 097376128A for ; Mon, 14 Jun 2021 13:23:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233470AbhFNNZO (ORCPT ); Mon, 14 Jun 2021 09:25:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233102AbhFNNZO (ORCPT ); Mon, 14 Jun 2021 09:25:14 -0400 Received: from mail-ed1-x533.google.com (mail-ed1-x533.google.com [IPv6:2a00:1450:4864:20::533]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A8B0C061574; Mon, 14 Jun 2021 06:23:11 -0700 (PDT) Received: by mail-ed1-x533.google.com with SMTP id w21so46411846edv.3; Mon, 14 Jun 2021 06:23:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=RUx64tq9BpIwVZt1SvBA673QJ3mEok3gmg2Ilw9YkAw=; b=edAA06FfFrqR55mdDZHjATZP2XflwzR4lokED4y77aoKEyLqnkDPxKYC+w90mKk++U pFg2SuYmbbV+qjgaC4ZlHlbsWxhWVWxpsPZkBYDrAIhmmlaDA6akh1MjwgZkCS1YKVEK G16IW7FfBqkvb6GUHhfbBPA733Z4KcHU6oPf0fH9XpqakBA2qgugMb1RNPD3gcBwh6fo 7nEeIL+vZkuKxHYbw+Miny8+AXwS69hDPMUzbPbZABibnW3XiWIwDiqpQFpFv9IPxuNr 8pXq3oB3bkpfoAOjdjSMJdrX7dJV3cC+ziAtKE6Gt8NFehxL7zJPxnok+VpOZlAZs01K ue/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=RUx64tq9BpIwVZt1SvBA673QJ3mEok3gmg2Ilw9YkAw=; b=PrWdmsJcGl8pwXDyjTCCrfxhDi4R22zBLfcY8X49L3cZb+20Gq1yfAXbzhT7x7GbIF t9NwLpSyx7OipqsXIJ1WJk73XTpmCAkLPANhOR0NdGGozJjFpeFlL2LU6721a6fRLgxE C2oryufYyVxTKmwBDDggUzuMKZ8f7cTNJSlL41jFXiKEy9CDL9cd17p0hzNqkCEOp2jn WsXMcgZOMyDHEgiiZ2v97QMBAOoih68cCbtRryN2uZ1JQceawqqA+RkdVoSbIkHQW95B 44oqgA7KI2Pfcodca3Dp+g88YejS1S/tZ9q8lHmBCeyVlKqmRELPz0pTE8DK5/pkkK1W iQoA== X-Gm-Message-State: AOAM532nsx5bBgBSRL/qUjQ1reFy3g7B/u8HtCpPmNeSnGGDR8re2ixk eiWZFR/FhpYhXj8TA/OccSFbtn/7UK9WA7hTjBA= X-Google-Smtp-Source: ABdhPJwj7ZM5/GfOD9oHG48QJhQeKaOGZLGhXIFLtD6xyup/eUmEGjWlC27fAHOQoenMThw9CnBQR/XbRSYRc5ooilY= X-Received: by 2002:a05:6402:22f9:: with SMTP id dn25mr16985626edb.241.1623676989585; Mon, 14 Jun 2021 06:23:09 -0700 (PDT) MIME-Version: 1.0 From: Dongliang Mu Date: Mon, 14 Jun 2021 21:22:43 +0800 Message-ID: Subject: Suggestions on how to debug kernel crashes where printk and gdb both does not work To: alex.aring@gmail.com, "David S. Miller" , Jakub Kicinski , linux-kernel , linux-wpan@vger.kernel.org, netdev@vger.kernel.org, stefan@datenfreihafen.org, syzkaller-bugs , syzbot+b80c9959009a9325cdff@syzkaller.appspotmail.com, Dan Carpenter , Greg KH Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-wpan@vger.kernel.org Dear kernel developers, I was trying to debug the crash - memory leak in hwsim_add_one [1] recently. However, I encountered a disgusting issue: my breakpoint and printk/pr_alert in the functions that will be surely executed do not work. The stack trace is in the following. I wrote this email to ask for some suggestions on how to debug such cases? Thanks very much. Looking forward to your reply. [] kmalloc include/linux/slab.h:556 [inline] [] kzalloc include/linux/slab.h:686 [inline] [] hwsim_alloc_edge.constprop.0+0x22/0x80 drivers/net/ieee802154/mac802154_hwsim.c:385 [] hwsim_subscribe_all_others drivers/net/ieee802154/mac802154_hwsim.c:709 [inline] [] hwsim_add_one+0x3b3/0x640 drivers/net/ieee802154/mac802154_hwsim.c:802 [] hwsim_probe+0x44/0xd0 drivers/net/ieee802154/mac802154_hwsim.c:848 [] platform_probe+0x81/0x120 drivers/base/platform.c:1447 [] really_probe+0x159/0x500 drivers/base/dd.c:576 [] driver_probe_device+0x8b/0x100 drivers/base/dd.c:763 [] device_driver_attach+0x105/0x110 drivers/base/dd.c:1039 [] __driver_attach drivers/base/dd.c:1117 [inline] [] __driver_attach+0xa1/0x140 drivers/base/dd.c:1070 [] bus_for_each_dev+0xa9/0x100 drivers/base/bus.c:305 [] bus_add_driver+0x160/0x280 drivers/base/bus.c:622 [] driver_register+0xc3/0x150 drivers/base/driver.c:171 [] hwsim_init_module+0xae/0x107 drivers/net/ieee802154/mac802154_hwsim.c:899 [] do_one_initcall+0x63/0x2e0 init/main.c:1249 [] do_initcall_level init/main.c:1322 [inline] [] do_initcalls init/main.c:1338 [inline] [] do_basic_setup init/main.c:1358 [inline] [] kernel_init_freeable+0x1f4/0x26e init/main.c:1560 [] kernel_init+0xc/0x1a7 init/main.c:1447 [] ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 [1] https://groups.google.com/g/syzkaller-bugs/c/iEEZ_UOvoEY/m/6sm4bt6EAgAJ -- My best regards to you. No System Is Safe! Dongliang Mu