From nobody Tue Apr 05 21:05:25 2022 X-Original-To: freebsd-fs@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 88D351AA2AEF for ; Tue, 5 Apr 2022 21:05:44 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-oi1-f176.google.com (mail-oi1-f176.google.com [209.85.167.176]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1D4" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4KY0Y34yC6z4l03 for ; Tue, 5 Apr 2022 21:05:43 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-oi1-f176.google.com with SMTP id k10so455178oia.0 for ; Tue, 05 Apr 2022 14:05:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=nrAMl7ZHlsFPYpM9wxmvvmj3kRdeBK/cPsha8XmhHBU=; b=l4rxBIbjaIvZPwtT+TcTOL7FYgsDC9vb9ditnmpIrgjEeXcVRNXoaXdIVGhP5ACeyq lOKlmpNj8XqF34bmx62HqyCm8E/OXbgXHBh/EXHPYxVwjrVpMrsmK2Sc2eWICfEPvp6P 2S6P/aDtqF0GayX0wG295PQpFsr8dX3Droa1FgSAX+HBpqNgEC7BBc1qNYi+jSP9hjO/ qN/AgVPeVEyz71BE+49Ln94GbFQfGIHWTw9tMlHv7lCp07F6BBc+vP46BzfoB03NQN7q kLd05eyI+azoIKGj36Sb2WfCfT37n4VtCmN/6Kyf/HIofuAp9iY4YLaxGErL8NvOrIGG GTBA== X-Gm-Message-State: AOAM532deOeJsRdDl3Jl0Q7YCw+FlSgZR2PVwgPn2FGGBWbLlmn4wYwE AMhwjPvTmrk870WPqbJ0kDu5Q2IxyZ3WDMd3W2VXCD39QSE= X-Google-Smtp-Source: ABdhPJxzjNZrk2U2pJATIGeF6sOoSLaXmGQZ5PQRK4Ar3YySfaYE0wB3mvpMybiGjdeLnLTLrAZ863wZ7MDLX0kGFts= X-Received: by 2002:a05:6808:1884:b0:2da:5cc2:2bbb with SMTP id bi4-20020a056808188400b002da5cc22bbbmr2329711oib.72.1649192736535; Tue, 05 Apr 2022 14:05:36 -0700 (PDT) List-Id: Filesystems List-Archive: https://lists.freebsd.org/archives/freebsd-fs List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-fs@freebsd.org MIME-Version: 1.0 From: Alan Somers Date: Tue, 5 Apr 2022 15:05:25 -0600 Message-ID: Subject: Hour-long sleeps in the ZFS write throttle: fix for 13.1 ? To: freebsd-fs Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 4KY0Y34yC6z4l03 X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of asomers@gmail.com designates 209.85.167.176 as permitted sender) smtp.mailfrom=asomers@gmail.com X-Spamd-Result: default: False [-1.90 / 15.00]; R_SPF_ALLOW(-0.20)[+ip4:209.85.128.0/17:c]; TO_DN_ALL(0.00)[]; NEURAL_HAM_SHORT(-1.00)[-0.996]; FORGED_SENDER(0.30)[asomers@freebsd.org,asomers@gmail.com]; SUBJECT_ENDS_QUESTION(1.00)[]; R_DKIM_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; FROM_NEQ_ENVFROM(0.00)[asomers@freebsd.org,asomers@gmail.com]; ASN(0.00)[asn:15169, ipnet:209.85.128.0/17, country:US]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-0.90)[-0.900]; TO_DOM_EQ_FROM_DOM(0.00)[]; FREEFALL_USER(0.00)[asomers]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-fs@freebsd.org]; DMARC_NA(0.00)[freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; RCVD_IN_DNSWL_NONE(0.00)[209.85.167.176:from]; MLMMJ_DEST(0.00)[freebsd-fs]; RWL_MAILSPIKE_POSSIBLE(0.00)[209.85.167.176:from]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[] X-ThisMailContainsUnwantedMimeParts: N All year long I've occasionally seen my ZFS processes get blocked in dmu_tx_wait. They stay blocked for more than an hour but eventually recover. I finally found the cause: an integer overflow bug in ustosbt. The fix is simple enough, but my question is: should we try to commit this in time for 13.1-RELEASE? It's a very disruptive bug, but also very hard to trigger. It takes a pretty highly congested ZFS system to trigger it. In theory the bug could affect other subsystems, too. https://github.com/openzfs/zfs/issues/13289 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=263073