From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B08BF47F766; Tue, 25 Aug 2026 16:53:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787676804; cv=none; b=nhy7QgGabuwhxDumz0yP/KCzhsqvb9q7iCHtiyHQ163wVVuMK07VQ8AkTgtVOsXvyFOAd/OpN4ak0vSeYglqDcO86VUcYXBfCdX659tX/WXKs/DKiLl3kcv2fAo2lisauJr5DqAC//pgV3qjB9cZqRuTx4azCGqaAfpj2+XPzeY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787676804; c=relaxed/simple; bh=wcF7uM94hR3OYHjUR0deVPFNJXkbu82Yd2mt83M2Wcs=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=gFxkuqA8ZMDiqSXXbVtRrh7i5uy4GifIc7frYuyLJV56v8nA+/s6CroP/kJz/S3fif80Jw10fyEkwEU40ftEqKfW+ojNV5HKM66oSwA8EgyTHi24k7prG2zeHjLDlnOZZc6Q/bkiMFzt549QHNCXN6/I2ksYDbOZMGL64m2kl24= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eB1GPAna; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eB1GPAna" Received: by smtp.kernel.org (Postfix) with ESMTPS id 4A8B5C2BCB8; Tue, 25 Aug 2026 16:53:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1787676804; bh=wcF7uM94hR3OYHjUR0deVPFNJXkbu82Yd2mt83M2Wcs=; h=From:Subject:Date:To:Cc:Reply-To:From; b=eB1GPAnaW6PhODBaCOEAFJlJ05eTAUns0Ipv3uwOL5Aigg9kw32tMQW+ZxIH9I02I WEMExTM/iEWYRLkmc1zOV4IHRfvrIPHP3h55dFqK40rPtQuK67vQQvRijta1HufbFQ 4wD3OVcwbhDvnYacl335eKDhZUnj9/vQs25barrza4Oh/doWrXsjRnkwxgn4xcd7B8 0PL2yzB0ojnBscczry8GCH9jTEKHOvvD1u2IRdcqM9b2g5VLlpUtLYL8ud6ePgvSpM gM7p8v3XoxuWe+05a2wSy0bGF8eRprAfjfzwr2j5gyrdXFq//gVi1bJAzF0KlCXNR5 Ow85pCmiMPKIg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35936C61DBC; Tue, 25 Aug 2026 16:53:24 +0000 (UTC) From: Ivan Immanuel Shaji via B4 Relay Subject: [PATCH v2 0/2] tracing: Fix remote reader page swap failures Date: Tue, 25 Aug 2026 12:52:48 -0400 Message-Id: <20260825-kernel-patch-1-v2-0-bb3461807a32@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAAAAAAAC/3XMQQ6CMBCF4auQWTumLbYBV97DsKh0pBOhJS0hG sLdrexd/i953waZElOGa7VBopUzx1BCnSrovQ0DIbvSoIQyolEaX5QCjTjbpfco0TXCUO1ISKu hnOZET34f4L0r7TkvMX0Of5W/9S+1ShRIbX1prRUPafRtmCyP5z5O0O37/gWRNM8/rAAAAA== X-Change-ID: 20260825-kernel-patch-1-d806e3de01a5 To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Vincent Donnefort Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, stable@vger.kernel.org, Ivan Immanuel Shaji X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787676803; l=1659; i=ivanimmanuel1234@gmail.com; s=20260825; h=from:subject:message-id; bh=wcF7uM94hR3OYHjUR0deVPFNJXkbu82Yd2mt83M2Wcs=; b=XIY564obFbHXJ78STHg+tNDgIkiB60qq73/Njm1V1Lf53UcL3eyb/0jAPKaHOhGhoJH7WRn8t J3a3736XDdaC/aXpBWgDgeJvdAXR9ZemwK0qoaBLGUfy8x424EGdLoU X-Developer-Key: i=ivanimmanuel1234@gmail.com; a=ed25519; pk=Wx8O3UUs3XneDkbqbOJJnlNdWSpEf2tWbTAoE7/vnqE= X-Endpoint-Received: by B4 Relay for ivanimmanuel1234@gmail.com/20260825 with auth_id=975 X-Original-From: Ivan Immanuel Shaji Reply-To: ivanimmanuel1234@gmail.com The simple ring buffer's reader-page swap retry loop mishandles its last attempt. A success at that point is reported as an error, while a failure is allowed to continue into the pointer updates. The remote ring buffer consumer compounds callback failures by warning and continuing with stale reader metadata. Fix the retry result in the provider, then stop the remote consumer before it mutates its local page list when the swap fails. These paths are used by remote tracing, including arm64 nVHE EL2 tracing and CONFIG_TRACE_REMOTE_TEST. Testing: make C=2 W=1 kernel/trace/simple_ring_buffer.o kernel/trace/ring_buffer.o scripts/checkpatch.pl --no-tree (each formatted patch) No runtime reproducer was run. The two final-attempt outcomes follow from the retry counter's post-decrement semantics. An arm64 cross-compiler was not available. --- Changes in v2: - Report callback failures with pr_warn_ratelimited() instead of WARN_ON_ONCE(), as suggested by Vincent Donnefort. - Add Vincent Donnefort's Reviewed-by tag to patch 1. - Link to v1: https://lore.kernel.org/r/20260825-kernel-patch-1-v1-0-e9349aa0b165@gmail.com --- Ivan Immanuel Shaji (2): tracing: Fix retry exhaustion in simple ring buffer reader swap ring-buffer: Stop remote reader update when page swap fails kernel/trace/ring_buffer.c | 7 +++++-- kernel/trace/simple_ring_buffer.c | 4 ++-- 2 files changed, 7 insertions(+), 4 deletions(-) --- base-commit: 66498c75b4f8017f62d720d9b59675bdf3abce91 change-id: 20260825-kernel-patch-1-d806e3de01a5 Best regards, -- Ivan Immanuel Shaji