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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7D9FCD43369 for ; Fri, 12 Dec 2025 03:56:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C8BA46B0006; Thu, 11 Dec 2025 22:56:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C63076B0007; Thu, 11 Dec 2025 22:56:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B79386B0008; Thu, 11 Dec 2025 22:56:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id A44956B0006 for ; Thu, 11 Dec 2025 22:56:54 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 1C06058CF9 for ; Fri, 12 Dec 2025 03:56:54 +0000 (UTC) X-FDA: 84209457948.18.4BCCBA1 Received: from mail-yw1-f179.google.com (mail-yw1-f179.google.com [209.85.128.179]) by imf20.hostedemail.com (Postfix) with ESMTP id 672E11C0002 for ; Fri, 12 Dec 2025 03:56:52 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=Nx6UNRgl; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf20.hostedemail.com: domain of hughd@google.com designates 209.85.128.179 as permitted sender) smtp.mailfrom=hughd@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765511812; a=rsa-sha256; cv=none; b=enkYfc0v03BU8VJB9sU8nm3CQuBkWW1DtIXy3a+grF76efnRm/aZXWqpBg9+/1UtmWQ2YA TpysQm8wlqRoOoEpTNpbbtc9HnXH3oPGTH4aYuopHRGMRkRB1BxP2dflFaxPPSgAWaaW26 eSELkfwC39hDSx3fH+UgxOmdh/DAQOs= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=Nx6UNRgl; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf20.hostedemail.com: domain of hughd@google.com designates 209.85.128.179 as permitted sender) smtp.mailfrom=hughd@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1765511812; 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:in-reply-to: references:dkim-signature; bh=xeFWRCGQLVfdTlq5pXNNJICaPMuBvs9CA3bbYx0xV40=; b=1EL2aXCxuLp/+NXiNKYOBfBVV1//Q06m4T29/xJ+qCPsRTl9KtIEjkCblZd6I0xKbb0k+s nT9zW8dDaaUxHAga8rlZW9LSthEMVmqz30rHY54evoag2vuND6u5ECAFngGvOIdtcq3zl5 bRYJTnfSqicuNX6cPAAdhvl2SkXHFIM= Received: by mail-yw1-f179.google.com with SMTP id 00721157ae682-78a835353e4so8740177b3.2 for ; Thu, 11 Dec 2025 19:56:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1765511811; x=1766116611; darn=kvack.org; h=mime-version:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to; bh=xeFWRCGQLVfdTlq5pXNNJICaPMuBvs9CA3bbYx0xV40=; b=Nx6UNRgl+KS9z5NroHrtz62u2XwFCm21JweutjCuX7Q3hJbMRfj5yIMPFOSDhwG9pV d8rOHsf5ohiLGew4N0hwc4UsRtjc9uAkdatnYIqHZOltTBTh+IeWghG3Vj32i7TnoX53 6ih251F74/Xsqi9Q95ku2sz7OF1VKOKa+EHgQSb8H+ZZc5GEG3mKyAD3oT4/hj85i7Ou DltiZT98188uhPEH48mWAIeEa/5s5NDyvl4FbVXVcRO9ZjuXGrBeyZd8LyQtIChSe2BR 4gq/02yxrleFYYJ5apwAOTSdY0E/qkQ1/FcSFdd9KKfUxf2uIKcgN9mPFeh1Pl2LwuRI CgSQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765511811; x=1766116611; h=mime-version:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=xeFWRCGQLVfdTlq5pXNNJICaPMuBvs9CA3bbYx0xV40=; b=BXYnYgVuzihIpi6xc8kidOcGYxkhwDQrvNQ1VkUHUEs0hffVMseMJuOlbTWyXmJ/mC SXh9zIDzCWukzNxmhxHB3XcwdO3pNwNG5Pa6GmuejQwd6QA2BxY7kAcb2dQzhi2XjSw2 MJ1L+n8qzguIIsqPN/8qAoRIMQziRt68a3rp9RzFQELEDZ8yCNyg0VnAD+n2ZXN71AgW crddnYZ1OivNQrZ73jAFqiabbBzi/2sVJCnmMBOkBNGSHGekFaF6wgWoNWLMWGc0XfPp nUP/gyd/M/DlHu4Lbbgay8OZWmq5fhp5EqBvQUTQzZGa3eKt+ZusbvKxlgA7Z/sV7uKq nCfQ== X-Forwarded-Encrypted: i=1; AJvYcCXikqQurx5u3L1LWlaO0WasTvnBYxYsCLwJffVmdVXYokFvNXDpZ5Sf+lhSAtBoOzG1zE1Vk5f/iA==@kvack.org X-Gm-Message-State: AOJu0YyZouMhfL9kGSLaGZzPuy/yTvJzgtH/wd8+SEOC4R7XT9Y8jJZm BEssveyWVPb1CIpHXossmvSeuoj5tMZmljLiL5wLBjQ2NYx8FrvSBtBDPp4iHD7k1w== X-Gm-Gg: AY/fxX5i+s8vXGuLzaguFcd4oJfw98VDtMqo5/py/lqCodxiQvHEYwalRzOPyps+ijp DKoK7xZWf4iEeRQyl6a5+CY6Hha0VQMJTrd9s31gHqSqGzTbhO1MwW4AOqi3/6I6pp1LYK/ie47 XS4fqHfaIWbbWPDC4XNsH4+er4veW4iWQtfqN7+Ll+i3msYLs49HJVM8M7LQWu+9nJlrurq9ZIK 9jAbUnkD7Ha3wAoqaxXoCC107kB/NVHsT/cvZn3je82jIv/PKD9xL/GYWPzGMH/UCE/a9ShBuuS qo5g4UDsaNlUdNzL72EFIQRdnto3S5jeGNiSYdXVP94xI+c/jIsGkxEcfe3lDSJ5YpoMsoIf/Kh +yckutztlrgVqDsWwLuwwQU3uCdKm3s6bAtv0eelgl2ww/by58RQWe/Efp6aDXG7LwONpZjs1rw p90xYfm45Lg7z0Et91jYhTt+zxO/XuQ14tZLXvdc76hfKaR3iB6PAR7qkvcnR/xudC8ywMhZA= X-Google-Smtp-Source: AGHT+IE/UYWvWx/nJFV7pIAxmMrHkR+lE0t2mrgPpTbjSQpL/ST9/mf7gIbX2nmyWaYnzBbvDqZ7/g== X-Received: by 2002:a05:690c:61ca:b0:789:4f19:7fb3 with SMTP id 00721157ae682-78e66ea6d0bmr7619027b3.68.1765511811239; Thu, 11 Dec 2025 19:56:51 -0800 (PST) Received: from darker.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id 00721157ae682-78e6a40fc41sm864367b3.29.2025.12.11.19.56.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Dec 2025 19:56:49 -0800 (PST) Date: Thu, 11 Dec 2025 19:56:38 -0800 (PST) From: Hugh Dickins To: Al Viro cc: Christian Brauner , Andrew Morton , Baolin Wang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: 6.19 tmpfs __d_lookup() lockup Message-ID: <47e9d03c-7a50-2c7d-247d-36f95a5329ed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 672E11C0002 X-Stat-Signature: 4akawn59g59yuzok7zigng94c5meyyrp X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1765511812-398290 X-HE-Meta: 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 /+uGlO/7 10/Ww/PCC+PKcIZ2zlUbuAJHPD/LyTiFLlvWkGDuBGiSP2a+dUCK9u809JHOne57aYCf15s/70SCuRfLLMjscF/Q9dU2TlCOHBwbdPyPhGe2fBlx1vpjLOO3hF/zs5DRTxkfSiMwPOWt7DN8CaXCYEXUs/2946zAeBiETa4hT5rP3LnQx954x+ihy6xNBSDM3oyiPtqls5fl3HL7hExXRsvhMI5NJmv+ZAYO+qwUPEA274/cWqiZ7QVxAsAikrZmbjNgyukDMjZXhm+mjonLFBTlEzYQ93YSYA842gWBRy7q0UokY5fSlopRhNhyGHRzbGvbCctb0CVQHc1CmI+50fy1RhHsE0HguTo1NoMasetzXTI/38MyKXicPL44Pw7QF4jMdXG13wZhtj3wtDkQUvqG46A== 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 Al, Though good for ordinary usage, your persistency mods for 6.19 cause tmpfs to lockup in __d_lookup() during several fsstressing xfstests: fairly reliably in generic/269, generic/476, generic/650, generic/750, less reliably in generic/013, generic/585. Typical dmesg below. I have not spotted what's wrong: better hand over to you. Of course, 2313598222f9 ("convert ramfs and tmpfs") (of Feb 26 2024!) comes out as the first failing commit, no surprise there. I did try inserting a BUG_ON(node == node->next) on line 2438 of fs/dcache.c, just after __d_lookup's hlist_bl_for_each_entry_rcu(), and that BUG was immediately hit (but, for all I know, perhaps that's an unreliable asserition, perhaps it's acceptable for a race to result in a momentary node == node->next there). I did try hacking on xfstests common/rc, to allow ramfs where tmpfs is enabled (and _df_device() then needs $DF_PROG -a to show ramfs). I did not get a lockup or crash from any of them on ramfs (and 476 and 750 actually passed). I don't draw any conclusion from that, maybe ramfs just does not support some of the options which help fsstress to generate the issue; but it might be useful background info. Hoping you can soon guess what's gone wrong, or ask for more info, thanks, Hugh [ 54.354788] run fstests generic/269 at 2025-12-10 19:40:16 [ 114.660512] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 114.670705] rcu: Tasks blocked on level-0 rcu_node (CPUs 0-7): P3185 [ 114.681006] rcu: (detected by 6, t=15007 jiffies, g=3377, q=6940 ncpus=8) [ 114.691346] task:fsstress state:R running task stack:0 pid:3185 tgid:3185 ppid:3059 task_flags:0x400140 flags:0x00080003 [ 114.702226] Call Trace: [ 114.712908] [ 114.723528] __schedule+0x67c/0x6c5 [ 114.734245] ? __d_lookup_rcu+0x7a/0x9c [ 114.744921] ? irqentry_exit+0x27/0x35 [ 114.755547] ? sysvec_apic_timer_interrupt+0xa8/0xae [ 114.766300] ? asm_sysvec_apic_timer_interrupt+0x1b/0x20 [ 114.776953] ? __d_lookup+0x37/0xad [ 114.787357] ? __d_lookup+0x2f/0xad [ 114.797700] ? d_lookup+0x2b/0x42 [ 114.807970] ? lookup_dcache+0x1f/0x60 [ 114.818265] ? lookup_one_qstr_excl+0x1a/0xbe [ 114.828525] ? do_renameat2+0x1d1/0x3e4 [ 114.838808] ? getname_flags+0x4b/0x17a [ 114.849093] ? __do_sys_rename+0x36/0x3e [ 114.859363] ? __x64_sys_rename+0x11/0x13 [ 114.869634] ? x64_sys_call+0x34d/0xe2c [ 114.879797] ? do_syscall_64+0x53/0x123 [ 114.889820] ? entry_SYSCALL_64_after_hwframe+0x4b/0x53 [ 114.899748]