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[198.84.189.58]) by smtp.gmail.com with ESMTPSA id y19-20020a05620a44d300b006a6a4b43c01sm7996827qkp.38.2022.06.06.11.17.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Jun 2022 11:17:28 -0700 (PDT) Date: Mon, 6 Jun 2022 14:17:26 -0400 From: Mark Johnston To: Paul Floyd Cc: FreeBSD Hackers Subject: Re: Hang ast / pipelk / piperd Message-ID: References: <84015bf9-8504-1c3c-0ba5-58d0d7824843@gmail.com> List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 4LH1tL1qpLz4tvp X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20210112 header.b=CymjQVZ7; dmarc=none; spf=pass (mx1.freebsd.org: domain of markjdb@gmail.com designates 2607:f8b0:4864:20::f31 as permitted sender) smtp.mailfrom=markjdb@gmail.com X-Spamd-Result: default: False [-1.47 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36]; RCVD_COUNT_THREE(0.00)[3]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; RCPT_COUNT_TWO(0.00)[2]; FREEMAIL_TO(0.00)[gmail.com]; FORGED_SENDER(0.30)[markj@freebsd.org,markjdb@gmail.com]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; FROM_NEQ_ENVFROM(0.00)[markj@freebsd.org,markjdb@gmail.com]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20210112]; FROM_HAS_DN(0.00)[]; NEURAL_SPAM_SHORT(0.23)[0.234]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; DMARC_NA(0.00)[freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2607:f8b0:4864:20::f31:from]; MLMMJ_DEST(0.00)[freebsd-hackers]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[] X-ThisMailContainsUnwantedMimeParts: N On Wed, Jun 01, 2022 at 11:27:52PM +0200, Paul Floyd wrote: > On 6/1/22 14:16, Mark Johnston wrote: > > The fact that the problem apparently only occurs with 1 CPU suggests a > > scheduler bug, indeed. > > Here is the fresh procstat output I was able to reproduce the problem locally and narrow down the bug somewhat. If you can test a kernel patch, please try this one: https://reviews.freebsd.org/D35415 . I verified that it solves the hang in my test setup, but I didn't go any further than that yet.