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 1BFEAC43217 for ; Mon, 23 May 2022 22:14:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230501AbiEWWOY (ORCPT ); Mon, 23 May 2022 18:14:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229697AbiEWWOW (ORCPT ); Mon, 23 May 2022 18:14:22 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB9C56D945; Mon, 23 May 2022 15:14:20 -0700 (PDT) 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 sin.source.kernel.org (Postfix) with ESMTPS id E4A3CCE1941; Mon, 23 May 2022 22:14:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17BD8C385A9; Mon, 23 May 2022 22:14:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653344057; bh=BtnYCdlUBKX6YqS/BraKh22u8nz1TCw7j+9R1vskYOQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=k9BhonP0X+z778fxt/u02FGrHj5D510oCITyE4f6lDSzAPgfHnXUes/jfy4VfLrE/ 3QbasTeMap/V1oSB5s7BQ267SqGCKHWEc5s/yce5mwtQJluyG76bOMklKJ5vQedHxf UZfm7iH5QC6Nximri882B/sWSXl0jnfN6ea1UZh3zNCHSML5+0rVqGGnf7w04x01at F/dxZl77ZfP6VKQ0UNzEXcCS1hRU9XQfHPPtt1KIs1KwWohxf0SXgU2U2ODK2gtO9n 0Kramiu5uPQ5tbNXMh/2cRhdp0/W3KdxANznXrGIncJHq16yDli+3UX74fpP9Rzqpu 15hZuZYOOheFQ== Date: Mon, 23 May 2022 15:14:14 -0700 From: Nathan Chancellor To: Saravana Kannan Cc: Jonathan Corbet , Greg Kroah-Hartman , "Rafael J. Wysocki" , "Rafael J. Wysocki" , Rob Herring , Linus Walleij , Will Deacon , Ulf Hansson , Kevin Hilman , Thierry Reding , Mark Brown , Pavel Machek , Geert Uytterhoeven , Yoshihiro Shimoda , Paul Kocialkowski , linux-gpio@vger.kernel.org, linux-pm@vger.kernel.org, iommu@lists.linux-foundation.org, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v1] driver core: Extend deferred probe timeout on driver registration Message-ID: References: <20220429220933.1350374-1-saravanak@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 23, 2022 at 01:04:03PM -0700, Saravana Kannan wrote: > On Mon, May 23, 2022 at 8:17 AM Nathan Chancellor wrote: > > > > On Fri, May 20, 2022 at 05:15:55PM -0700, Saravana Kannan wrote: > > > On Fri, May 20, 2022 at 5:04 PM Nathan Chancellor wrote: > > > > > > > > On Fri, May 20, 2022 at 04:49:48PM -0700, Saravana Kannan wrote: > > > > > On Fri, May 20, 2022 at 4:30 PM Nathan Chancellor wrote: > > > > > > > > > > > > Hi Saravana, > > > > > > > > > > > > On Fri, Apr 29, 2022 at 03:09:32PM -0700, Saravana Kannan wrote: > > > > > > > The deferred probe timer that's used for this currently starts at > > > > > > > late_initcall and runs for driver_deferred_probe_timeout seconds. The > > > > > > > assumption being that all available drivers would be loaded and > > > > > > > registered before the timer expires. This means, the > > > > > > > driver_deferred_probe_timeout has to be pretty large for it to cover the > > > > > > > worst case. But if we set the default value for it to cover the worst > > > > > > > case, it would significantly slow down the average case. For this > > > > > > > reason, the default value is set to 0. > > > > > > > > > > > > > > Also, with CONFIG_MODULES=y and the current default values of > > > > > > > driver_deferred_probe_timeout=0 and fw_devlink=on, devices with missing > > > > > > > drivers will cause their consumer devices to always defer their probes. > > > > > > > This is because device links created by fw_devlink defer the probe even > > > > > > > before the consumer driver's probe() is called. > > > > > > > > > > > > > > Instead of a fixed timeout, if we extend an unexpired deferred probe > > > > > > > timer on every successful driver registration, with the expectation more > > > > > > > modules would be loaded in the near future, then the default value of > > > > > > > driver_deferred_probe_timeout only needs to be as long as the worst case > > > > > > > time difference between two consecutive module loads. > > > > > > > > > > > > > > So let's implement that and set the default value to 10 seconds when > > > > > > > CONFIG_MODULES=y. > > > > > > > > > > > > > > Cc: Greg Kroah-Hartman > > > > > > > Cc: "Rafael J. Wysocki" > > > > > > > Cc: Rob Herring > > > > > > > Cc: Linus Walleij > > > > > > > Cc: Will Deacon > > > > > > > Cc: Ulf Hansson > > > > > > > Cc: Kevin Hilman > > > > > > > Cc: Thierry Reding > > > > > > > Cc: Mark Brown > > > > > > > Cc: Pavel Machek > > > > > > > Cc: Geert Uytterhoeven > > > > > > > Cc: Yoshihiro Shimoda > > > > > > > Cc: Paul Kocialkowski > > > > > > > Cc: linux-gpio@vger.kernel.org > > > > > > > Cc: linux-pm@vger.kernel.org > > > > > > > Cc: iommu@lists.linux-foundation.org > > > > > > > Signed-off-by: Saravana Kannan > > > > > > > > > > > > I bisected a boot hang with ARCH=s390 defconfig in QEMU down to this > > > > > > change as commit 2b28a1a84a0e ("driver core: Extend deferred probe > > > > > > timeout on driver registration") in next-20220520 (bisect log below). > > > > > > > > > > > > $ make -skj"$(nproc)" ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- defconfig bzImage > > > > > > > > > > > > $ timeout --foreground 15m stdbuf -oL -eL \ > > > > > > qemu-system-s390x \ > > > > > > -initrd ... \ > > > > > > -M s390-ccw-virtio \ > > > > > > -display none \ > > > > > > -kernel arch/s390/boot/bzImage \ > > > > > > -m 512m \ > > > > > > -nodefaults \ > > > > > > -serial mon:stdio > > > > > > ... > > > > > > [ 2.077303] In-situ OAM (IOAM) with IPv6 > > > > > > [ 2.077639] NET: Registered PF_PACKET protocol family > > > > > > [ 2.078063] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this. > > > > > > [ 2.078795] Key type dns_resolver registered > > > > > > [ 2.079317] cio: Channel measurement facility initialized using format extended (mode autodetected) > > > > > > [ 2.081494] Discipline DIAG cannot be used without z/VM > > > > > > [ 260.626363] random: crng init done > > > > > > qemu-system-s390x: terminating on signal 15 from pid 3815762 (timeout) > > > > > > > > > > > > We have a simple rootfs available if necessary: > > > > > > > > > > > > https://github.com/ClangBuiltLinux/boot-utils/raw/bc0d17785eb67f1edd0ee0a134970a807895f741/images/s390/rootfs.cpio.zst > > > > > > > > > > > > If there is any other information I can provide, please let me know! > > > > > > > > > > Hmm... strange. Can you please try the following command line options > > > > > and tell me which of these has the issue and which don't? > > > > > > > > Sure thing! > > > > > > > > > 1) deferred_probe_timeout=0 > > > > > > > > No issue. > > > > > > > > > 2) deferred_probe_timeout=1 > > > > > 3) deferred_probe_timeout=300 > > > > > > > > Both of these appear to hang in the same way, I let each sit for five > > > > minutes. > > > > > > Strange that a sufficiently large timeout isn't helping. Is it trying > > > to boot off a network mount? I'll continue looking into this next > > > week. > > > > I don't think so, it seems like doing that requires some extra flags > > that we do not have: > > > > https://wiki.qemu.org/Features/S390xNetworkBoot > > > > If you need any additional information or want something tested, please > > let me know! > > I'll try to get qemu going on my end, but I'm not too confident I'll > be able to get to it in a timely fashion. So if you can help figure > out where this boot process is hanging, that'd be very much > appreciated. Sure thing! Information included below, I am more than happy to continue to test and debug as you need. > Couple of suggestions for debugging: > > Can you add a log to "wait_for_device_probe()" and see if that's > getting called right before the boot process hangs? If it does, can > you get a stacktrace (I just add a WARN_ON(1) when I need a stack > trace)? It's unlikely this is the case because > deferred_probe_timeout=1 still causes an issue for you, but I'd be > good to rule out. If I add a pr_info() call at the top of wait_for_device_probe(), I see it right before the process hangs. Adding WARN_ON(1) right below that reveals dasd_eckd_init() in drivers/s390/block/dasd_eckd.c calls wait_for_device_probe(): [ 4.610397] ------------[ cut here ]------------ [ 4.610520] WARNING: CPU: 0 PID: 1 at drivers/base/dd.c:742 wait_for_device_probe+0x28/0x110 [ 4.611134] Modules linked in: [ 4.611593] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.18.0-next-20220523-dirty #1 [ 4.611830] Hardware name: QEMU 8561 QEMU (KVM/Linux) [ 4.612017] Krnl PSW : 0704c00180000000 0000000000ce4b3c (wait_for_device_probe+0x2c/0x110) [ 4.612258] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 [ 4.612387] Krnl GPRS: 80000000fffff071 0000000000000027 000000000000000c 00000000017f91d8 [ 4.612457] 00000000fffff071 00000000017f9218 0000000001a655a0 0000000000000006 [ 4.612521] 0000000000000002 0000000001965810 00000000019d51a0 0000000000000000 [ 4.612585] 0000000002218000 000000000125bcc8 0000000000ce4b38 000003800000bc80 [ 4.614814] Krnl Code: 0000000000ce4b2c: e3e0f0980024 stg %r14,152(%r15) [ 4.614814] 0000000000ce4b32: c0e5ffff94cb brasl %r14,0000000000cd74c8 [ 4.614814] #0000000000ce4b38: af000000 mc 0,0 [ 4.614814] >0000000000ce4b3c: c0100054d1fa larl %r1,000000000177ef30 [ 4.614814] 0000000000ce4b42: e31010000012 lt %r1,0(%r1) [ 4.614814] 0000000000ce4b48: a784002d brc 8,0000000000ce4ba2 [ 4.614814] 0000000000ce4b4c: d727f0a0f0a0 xc 160(40,%r15),160(%r15) [ 4.614814] 0000000000ce4b52: 41b0f0a0 la %r11,160(%r15) [ 4.615698] Call Trace: [ 4.616559] [<0000000000ce4b3c>] wait_for_device_probe+0x2c/0x110 [ 4.616744] ([<0000000000ce4b38>] wait_for_device_probe+0x28/0x110) [ 4.616841] [<000000000196593e>] dasd_eckd_init+0x12e/0x178 [ 4.616913] [<0000000000100936>] do_one_initcall+0x46/0x1e8 [ 4.616983] [<0000000001920706>] do_initcalls+0x126/0x150 [ 4.617046] [<000000000192095e>] kernel_init_freeable+0x1ae/0x1f0 [ 4.617110] [<0000000000ce85a6>] kernel_init+0x2e/0x168 [ 4.617171] [<0000000000103320>] __ret_from_fork+0x40/0x58 [ 4.617233] [<0000000000cf5eaa>] ret_from_fork+0xa/0x40 [ 4.617352] Last Breaking-Event-Address: [ 4.617393] [<0000000000e0e098>] __s390_indirect_jump_r14+0x0/0xc [ 4.617481] ---[ end trace 0000000000000000 ]--- > Let's try to rule out if deferred_probe_extend_timeout() is causing > some issues. So, without my patch, what happens if you set: > deferred_probe_timeout=1 > deferred_probe_timeout=300 At commit 6ee60e9c9f2f ("MAINTAINERS: add Russ Weight as a firmware loader maintainer"), both deferred_probe_timeout=1 and deferred_probe_timeout=300 hang the boot. > If deferred_probe_timeout=1 causes an issue even without my patch, > then in addition, can you try commenting out the call to > fw_devlink_drivers_done() inside deferred_probe_timeout_work_func() > and try again? Sure, that does not appear to make a difference with deferred_probe_timeout=1. Cheers, Nathan