From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f43.google.com (mail-ed1-f43.google.com [209.85.208.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 015123542D4 for ; Tue, 6 Oct 2026 11:33:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791286427; cv=none; b=q2kdMzmOlnmzY3tnr/Ga9l3NtHj0RinJyt+glF+Xd9VkXCdN7OAMFqEqWQDZ5mdgxq+kZFXIg61mSoCXF5HxXQ1HAg50Ztn5kCAo1zpRJQvxgW+v7y/tlw8qEXTYvxVo0ACQUIP5O/tr/BXsX5cww9XwJiWb501woNLTXDooyPg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791286427; c=relaxed/simple; bh=rbvt+tFZXxO5cFLINWgZ71k4YVwvsng5rl3cw2NGZ6w=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=tHeS3aY9lY1mcqZW+3M7R01wCND3tu3kcFmc5uGUSWGH8CCAjrLuBJyZ6N2HActuKLmvWJtyfDqH8kafDoAVPrPskgQdphzc4g8CZb4w3MPEMijR8bp/8BEN+0JT3HieSKygTpx+TFlM+XOn278BpVtF/juSz75S9yXtji0rQyI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ou9jdrN5; arc=none smtp.client-ip=209.85.208.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ou9jdrN5" Received: by mail-ed1-f43.google.com with SMTP id 4fb4d7f45d1cf-6a9a20a5e72so653552a12.0 for ; Tue, 06 Oct 2026 04:33:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1791286424; x=1791891224; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=kcAdRzVf/u8zZAu+qB0ABmtM1m8Lw721MraQWUZf5XE=; b=ou9jdrN5E8suovejcv4mQx+crgmUN3BqXNrUiyYEK/04W/n7XeADOkHb03lSrOWrrr /4I770nVYiV1cuCd9t1Y7p3uRLtVTniUCS8y2Wu3+GSR868Xho1wjFxsVojn8lemrcdL uHw6ZHyRUQ+idtG6QnyBGbFjye1FLn7+BT3ED1u+bNjBzhtZf5iuU030HoAjf5wF1CUp KIGTD2wk5HWPUPFbJnQcpif2/9HfiCjqcmKfmAUvZ/zrq4tJ3A2VdnqdlTFx/AzcQ/KT Dw2VVb7KugaeYRO7DBBiY9Usx8higPnoIBmTS6uww1lFYSMGvTVG98sVUmVGomg0czh6 iFuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791286424; x=1791891224; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=kcAdRzVf/u8zZAu+qB0ABmtM1m8Lw721MraQWUZf5XE=; b=FeJs4vwwHS+pwk7SbFzl63dzDx4myPBgspp5VqHM1Lczgi0CMWuw72RaM743NmutA4 6mZqws1kOzRZ320fekxMLZrUiuSGeAiN02k3rgGzetcl6SW43JzjRVAngDYGVfGKN+// RDCwxAlSWZnbS1ZERk/d3naur62DQConkdUyWyQ/DEVeoO12dI+h3JUBkFxQz5ja5S84 6T0CFV2zCgYoyOYyEt+3ASSPaTGxHvdojTXu9tsn+MhFbGnsN7TLTOy1U0Wmn7aMEVRt mAbD3u4RD5FVFz2mcaAjRpOr99gLLmh2A5JaI369VggxqKuhcHt3AbqbralbTBiVfPUH W7cw== X-Forwarded-Encrypted: i=1; AKwUvByVSRw/H3ZawQEWs/C9PAcwne++uM6SSEb1GCyTw+TDuIcewWvGlZYwOAfZOqJ47jGE89+V3Og=@vger.kernel.org X-Gm-Message-State: AFq9FYJnmewdXELFqjVAAsMlwPafaown75OYew5uPe6ek5nFR/8Uz1uV x7DZsWMKeS7oCiRle12qFG19C5bGgi1X4MUhMeMGrLQ2YQYbgMsRbPr3 X-Gm-Gg: AYBFou0U/ATERScaRk1qP4+83z2UPNhYsZ9K8vk7Z342tdGpU3LwhUhewP8nijrR1Ft Qsk26Y26Ed+4UGSwcqpOm0voP50Mf1UG57ZvS/DjYw7EuNc6/M7a+4DK4AzuijKFMVxpOLoptLE GPhrcruPMwz+szxR/U8426JaONtULUK5EiasdW2wfOg/i8aR3HsEiUQMoRvLnvIAePo9PvP0grk 7uiwIYkAsWamLHkST5tyGLPNqy3FlRZ02wDWUbm7Om/SYiRIE8Ctudzrz9xTQDFb/FWePaoant9 EnDt2d81xZHmQibDCiCD9QB3WwA/Jbjcm2HCmzyMLLvukV7MPMw/NISrmrCwHqDB/zUDO5tvQJf ZDH1rdYt86sgguyVoHQREvKaRZnMYkYL3H2gp7IQ+djKWgbouYVsMHvvdKli/FgjDKzJB1AEZPt TTr17Y4x3coM4l9n06GyDFHi0RLCpeDujbW8Hc93LFUAcz1gYVK+XEhJRqNnu0nfFuw9atbkORd eZBLCFtpN67ck2toLJGO0Y+7bbYKgC3hFM8RKRheUZYK0LzFbv7KNGEmJnwV+AzcWpe/K3YHdlT zzkVdFuEhzFCe3AB4AwAKaHngtDElK56oafvcjARZH+lRRNB74x8EvLSXjA+MxkmOQSLBrGR+D1 6vIBaiAzNP7DpGIFSkCduRtphdYfB X-Received: by 2002:a05:6402:4512:b0:6ac:8b71:fd91 with SMTP id 4fb4d7f45d1cf-6afe2959a75mr1292168a12.3.1791286423860; Tue, 06 Oct 2026 04:33:43 -0700 (PDT) Received: from Ubuntu.ts.net (87-205-15-91.static.ip.netia.com.pl. [87.205.15.91]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6afb01e5937sm4465468a12.11.2026.10.06.04.33.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Oct 2026 04:33:43 -0700 (PDT) From: Krystian Kaniewski To: Vinicius Costa Gomes , Jamal Hadi Salim , Jiri Pirko , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Vladimir Oltean , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net 0/2] net/sched: taprio: fix RCU stall from replayed schedule entries Date: Tue, 6 Oct 2026 13:33:33 +0200 Message-ID: <20261006113335.241564-1-krystianmkaniewski@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit syzbot reported an RCU stall with a software taprio schedule made of a single 127 ns entry. When advance_sched() falls behind, it replays every missed entry inside the timer interrupt and the backlog only grows. Patch 2 makes it continue from the entry in progress instead. Patch 2 then checks for an admin schedule handover once after catching up. That requires the cycle_time_extension comparison to be monotonic, so the sum now saturates instead of wrapping. As a result a large extension can hand over to an admin schedule whose start time leaves no room for the timestamps derived from it. Initializing such a schedule already overflows today, and a carefully chosen extension can already reach it. Patch 1 rejects these schedules at configuration time and comes first, so the series never hands over to one. Krystian Kaniewski (2): net/sched: taprio: reject software schedules that overflow their timestamps net/sched: taprio: do not replay missed entries in advance_sched() net/sched/sch_taprio.c | 171 +++++++++++++++++++++++++++++++++++------ 1 file changed, 149 insertions(+), 22 deletions(-) base-commit: af39eb111ce6b5eba9c08513b62c4868eb7e7fd5 -- 2.53.0