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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 854BAE6B240 for ; Fri, 1 Nov 2024 11:02:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EC6A16B007B; Fri, 1 Nov 2024 07:02:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E76426B0082; Fri, 1 Nov 2024 07:02:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D42F26B0083; Fri, 1 Nov 2024 07:02:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id B6DFD6B007B for ; Fri, 1 Nov 2024 07:02:43 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 3E95541BF4 for ; Fri, 1 Nov 2024 11:02:43 +0000 (UTC) X-FDA: 82737237366.24.A143D52 Received: from mail-pf1-f169.google.com (mail-pf1-f169.google.com [209.85.210.169]) by imf28.hostedemail.com (Postfix) with ESMTP id DB04BC0006 for ; Fri, 1 Nov 2024 11:02:12 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=uC6n1IFh; spf=pass (imf28.hostedemail.com: domain of nogikh@google.com designates 209.85.210.169 as permitted sender) smtp.mailfrom=nogikh@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1730458782; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=owQfejAwjt42qdtK2q4XQLezl6oCKTj4spODHA7HEJk=; b=eE/1kyw44NFQeVsANjbNHRj6t/d4ROwjn7Esw/bo4wWkE8IeY6HeVCEE9lHGq0WichdWCb 9Z5vSY9U8HvnIn0/YGEcLJ+SybHNSLifJMOBvOIOUrahOD+g2LzoQSnnSsN0Ha1sQnbkqf Cuj3fqQRjhgylKqpsvQgc5NQ6WBKTU4= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=uC6n1IFh; spf=pass (imf28.hostedemail.com: domain of nogikh@google.com designates 209.85.210.169 as permitted sender) smtp.mailfrom=nogikh@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1730458782; a=rsa-sha256; cv=none; b=Svbdoy4up3Cuu4N6p6Y9grC9F+zENSFJc5oWrLheDS4IpGttEP6bfOj2gzcd5izeYmHB6p HkNNNp9L7dKeiSCrA14ooeCQx+TiDm5wHH3rQq6MtxhjZZSlNlApcH4SbYTDxJr0C/vr5w PXVlP4akdkjK4sTQ0K0cFM18AaC/ixw= Received: by mail-pf1-f169.google.com with SMTP id d2e1a72fcca58-720d5ada03cso181791b3a.1 for ; Fri, 01 Nov 2024 04:02:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1730458960; x=1731063760; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=owQfejAwjt42qdtK2q4XQLezl6oCKTj4spODHA7HEJk=; b=uC6n1IFh/nmAK78GlyxeUOBArZnbh8AdzJWOlGHDDrwWAscKPh3x8da0t6ZsT8M6sC yr/IO/vcS/Wfw3AsdIeVkMIJgJnfGnTk0kIWRZ0LPfM0rgR2aBUeR9hUKbyrUGU92Rh+ MJp5Tj5kg2HF8S3HXOXsV3haDmKfPqfP+D6Iv7civ9/zEfHS5CyTf8fp1hkL0ag9rUfn Xi3Gfl2hG0PB5DtE2Kan+q2JDSl7lWojPar+i42j//WN/maOdd1uURN/JZ1yIQgtnzW+ BfjfMrmQQvQ8IBN7FqScVdbpX4b6Sa9agf/hJGGDOOPl1bauR18XNWQqNO8EpMaEmpg2 iFHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730458960; x=1731063760; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=owQfejAwjt42qdtK2q4XQLezl6oCKTj4spODHA7HEJk=; b=Zq1nrBx3832kG695LeE8qOU0QsBrrw9+iTupxr7gAlun7OZSI5l4AWHwhx+JYLrCGD WCRd2fNGl5OcgbKcK9dHP2gGw5hvJMaWkr6zd2HfBbrOM+6/Ea3QU16+gbD50nwWp50s 6YS+jefyOsy9Es4d2lt0QeoAdmcI1mWHD2/AvB4z0UmjNrbwL3zW/qIow06QlJSwIaPX TZZZn6/tRtWVfIngqnfL2ewi3DEgBnvXBTLO/CeFc2aUozFIuWOFulrvKVABHsWedqYv w2eZ7AHRde4y26ts2OF+abmbg7khf2kDe64FwMbfzBuJ1Y8HpCP/yozYkW6jX4zroOzu 8TyA== X-Forwarded-Encrypted: i=1; AJvYcCXfyidTHJGIYculyHHwG7zvSwTMliGetaDGQRZ5I4A3R8NnjlHF/0ZtnflYbB7gJkXVaNdgD54Vpw==@kvack.org X-Gm-Message-State: AOJu0YylgaCyR0kLADegYEsqmetQdj7bBClg1R6yADGIlG19OZq/YFOY qcSz9X/ESuyFkFJXrAC9yYNyN0GNyQOnZOtwTS5T8SFc1kTwgt34pv6YG5YZohrw4dE6cHpzAxD 2gV0u43NuK9dBvR/peqMTdcana9UZGIggigsn X-Google-Smtp-Source: AGHT+IGYGUcLrS9AcbUA3W7RaZ46FWQiIIQNNpQcmoWGQSvBjcT7EQZEJ67x0XF5XrP43lKMOJdiE35osh17WnqfNWo= X-Received: by 2002:a17:90b:2dc5:b0:2e2:d434:854c with SMTP id 98e67ed59e1d1-2e93c12378dmr8319912a91.2.1730458959964; Fri, 01 Nov 2024 04:02:39 -0700 (PDT) MIME-Version: 1.0 References: <6723b31e.050a0220.35b515.0165.GAE@google.com> <2928b6e8-3928-411d-82b8-6b17be266deb@lucifer.local> In-Reply-To: <2928b6e8-3928-411d-82b8-6b17be266deb@lucifer.local> From: Aleksandr Nogikh Date: Fri, 1 Nov 2024 12:02:25 +0100 Message-ID: Subject: Re: [syzbot] [mm?] [input?] [usb?] INFO: rcu detected stall in brk (2) To: Lorenzo Stoakes Cc: syzbot , akpm@linux-foundation.org, jannh@google.com, liam.howlett@oracle.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com, vbabka@suse.cz, Alan Stern , Dmitry Vyukov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DB04BC0006 X-Stat-Signature: 579rtqc6r775g4bzbqt8r8s5nauxz9k9 X-Rspam-User: X-HE-Tag: 1730458932-311470 X-HE-Meta: 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 HtfhQlsS 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Lorenzo, On Thu, Oct 31, 2024 at 5:59=E2=80=AFPM 'Lorenzo Stoakes' via syzkaller-bug= s wrote: > > +Alan re: USB stalls > > On Thu, Oct 31, 2024 at 09:41:02AM -0700, syzbot wrote: > > Hello, > > > > syzbot has tested the proposed patch and the reproducer did not trigger= any issue: > > > > Reported-by: syzbot+7402e6c8042635c93ead@syzkaller.appspotmail.com > > Tested-by: syzbot+7402e6c8042635c93ead@syzkaller.appspotmail.com > > > > Tested on: > > > > commit: cffcc47b mm/mlock: set the correct prev on failure > > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.g= it/ mm-hotfixes-unstable > > console output: https://syzkaller.appspot.com/x/log.txt?x=3D1304a630580= 000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=3D6648774f7c3= 9d413 > > dashboard link: https://syzkaller.appspot.com/bug?extid=3D7402e6c804263= 5c93ead > > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for= Debian) 2.40 > > > > Note: no patches were applied. > > Note: testing is done by a robot and is best-effort only. > > OK this seems likely to be intermittant (and unrelated to what's in > mm-unstable-fixes honestly) and does make me wonder if the fix referenced > in [0] really has sorted things out? Or whether it has perhaps help > mitigate the issue but not sufficiently in conjunction with debug things > that slow things down. > > Because we keep getting these reports, that mysteriously don't occur if w= e > re-run (or hit other code paths), they seem to hit somewhat arbitrary par= ts > of mm, and because CONFIG_DEBUG_VM_MAPLE_TREE is set we spend a _long_ ti= me > in mm validating trees (this config option is REALLY REALLY heavy-handed)= . > > I note we also set CONFIG_KCOV and CONFIG_KCOV_INSTRUMENT_ALL which isn't > going to make anything quicker if the USB gets laggy. These are necessary for coverage-guided fuzzing. Though when we find and run reproducers, we don't actually set up /dev/kcov, so I guess the impact of coverage callbacks here is not that significant here. CONFIG_KASAN is likely slowing down things much more. > > I'm not sure if there's a human who can help tweak the config for these > hardware-centric tests at Google? At least tweaking the RCU stall time > anyway? We currently set: CONFIG_RCU_CPU_STALL_TIMEOUT=3D100 CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=3D21000 The expedited RCU timeout was limited to 21 seconds up to some time ago, but I guess now we can safely increase this number as well. I'll send a PR with syzbot config updates. --=20 Aleksandr > > In any case this continues not to look likely to be an actual mm issue as > far as I can see. > > In [0] we were stalled in a validate call which would align with the idea > that perhaps we were just dealing with a very very big tree and getting > slow down that way. > > Cheers, Lorenzo > > [0]:https://lore.kernel.org/all/967f3aa0-447a-4121-b80b-299c926a33f5@rowl= and.harvard.edu/ >