From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) (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 9EE8F302750 for ; Mon, 22 Dec 2025 08:01:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766390497; cv=none; b=RxDYYySdAAlnY9b/+PcEPEi7zGzzYVwnA19MDfZi2N5MkwQx/VpPws1nF+UgU1khQIC2m3eCkc7EULGZpjfqnaPHjgGH/y6GJ1knRh50t10L4DgrBzN7nvUo4hM5DpEWGDx/UQwdPu+JhEBYFxNFKeFcoc5IVSPnoIrMza4Sb+Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766390497; c=relaxed/simple; bh=U0b6/RRZoU9PJ37clj0ubioxb/HZFHSbQmsQdaqPnwU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=sfVWh6W7j3SwitBmZkTACozH8anYj2CKVejXvcPx7P10M37ouBLy1QhIcoLtl/6/v3hC0kKtukhQjRal2zIG+sFClJ6MMn9T/SH7d4NB3PbA5XKLKmCxHtXLBT8nmhfT9Eu6Q4/V4JVoyDlflrbU2ILgCpB2VOaODEMVeaRQihA= 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=kZ2yaeAi; arc=none smtp.client-ip=209.85.214.174 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="kZ2yaeAi" Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-2a0bae9aca3so52515925ad.3 for ; Mon, 22 Dec 2025 00:01:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1766390496; x=1766995296; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=v8zLCGtUEy59h/vvTVaYiE4AnuVfZ6wIueUdzudE/X8=; b=kZ2yaeAi7bum9MaKKD6+88hp9OejiTKJvt2flckbDXlMDwgbAkhTPRcRPoaQQffp5A t+lZfZTzlXk4XcdBXOCIOGb72h8YZ7uPkEt1FxEJ2GkyPijU9EQtxp849bgsoqUngANc yE7khI9UkQgavPH+iy0ZfZR0F9ArXi0SSXNODjZ6yA3Vo+CJrPRsCJbjcN03fyidiziq LUnpEfepppGUtnJenhtmjIyKHr7tJ/kNIm+AMtcPStYtFXEq2OgUQ2VGGRhS32j90GQS Nt+RlEvWU5vqW9gflHA8fE/lo7076PSWaDS12T7e00lQlPyh+uyaEdrc0ems+Rd4o7Qr bHxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1766390496; x=1766995296; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=v8zLCGtUEy59h/vvTVaYiE4AnuVfZ6wIueUdzudE/X8=; b=Q5DeOMWBabp4k4ZnoCRGjsgnivQIMNBfswc2uKmuPBgDv7uKlpzV5Q23uf+g2/KeYM z0BCnokM1Fo8OryDLPnNmjS6iLpUKGxwevWie+8BhqWyvJeSjTdBVG00LKXVyFoyqrEF KwWqqsjIyo5n2Qgko7BWzDD706enRMqfL2+EfTKr8mz8j64kPW3Lvzk1HPliOjMJH/tx rzldcdzPTQ3VDRd9WKoYx84mUeagHLknT6EghmiUvH/6Ny1ZGOHUiokpgiHL8m//ZNtb MC79YRC3M+piGmw/WQmfrKmP38pSQJNWhFCFe1VGTMvvsRfqom/FenBRFHcCQrAQQdtN qiZA== X-Forwarded-Encrypted: i=1; AJvYcCUVYspjlqrfRvh9upLxhzge8Rhe2XuTITpj0SP2iEqGXo1MNyfzXa7AXUebFO/4dcIT8r8JB0EH7PBsm5Bmzi0+c/4=@vger.kernel.org X-Gm-Message-State: AOJu0YwCbhk7DhLueB6cqLf2a2yVvoMTUsgGe/ZvvPmFCWO+wk/UhlVb pcJNFy9VTddP8Ssv35HwyyjDYiEC4Muk1ZMPZOLdd/Kk9vSFuWmOkn7J X-Gm-Gg: AY/fxX7qTDJsYNPnZ22GIf7uyFsg8cS1pS3rhw62Vwa5dxNCW6D8u62T23akeev0PFX v9YoT9U2guNE8LfRj1kQlaSuRfweUFNuZR9zvmudMTstNpXCLUZZIdHyQ/h+sO7h/h4sexLIhek tcHfmeg9bsf9xc1gopT2oi+wrpRxXhYnT4nz+wyL9zuwWFEQUKcIgyA8RefxtK2UBwG0SNjRGj8 3O9CWDNFa65+IDfoMc2uBwT5mjlcpsGCOS3tOR9k2LV5kpGAGGvuewSELKkTMUa2B1Duz1+gNu3 kK9DQCej1KY0hzNemoYZrDvuDIEDdeIGfz+N9L4jtoEHSCmdB3YQtSR9Ub8uHyVnqzdv0VTqwbQ hfXHbbyxtDn9jI5w3U429Q9XfW7NZlB0Z+Wuv01Y8NbW+rqeoItY+RfNiFzKWvVrLezBrY4BdGg cJKupH7CtZqSP1lhe2lYh+TQL1nSPdbn8VrqI= X-Google-Smtp-Source: AGHT+IGRVyFERy7XokCmRRlYiNa0pF4cWj/sV618kkaysFWs1qFh/tkntU/7uvjqRuWTOwS1Q9Ei1g== X-Received: by 2002:a17:903:fad:b0:271:479d:3dcb with SMTP id d9443c01a7336-2a2f2212bc9mr111129865ad.6.1766390495794; Mon, 22 Dec 2025 00:01:35 -0800 (PST) Received: from mi-ThinkStation-K.mioffice.cn ([43.224.245.232]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a2f3c82ab4sm89961165ad.32.2025.12.22.00.01.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Dec 2025 00:01:35 -0800 (PST) From: liujing40 X-Google-Original-From: liujing40 To: rostedt@goodmis.org Cc: alexei.starovoitov@gmail.com, andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, haoluo@google.com, john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, liujing.root@gmail.com, liujing40@xiaomi.com, martin.lau@linux.dev, mhiramat@kernel.org, sdf@fomichev.me, song@kernel.org, yonghong.song@linux.dev Subject: Re: [PATCH 2/2] bpf: Implement kretprobe fallback for kprobe multi link Date: Mon, 22 Dec 2025 16:00:46 +0800 Message-Id: <20251222080046.2312024-1-liujing40@xiaomi.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251218160925.3c02a721@gandalf.local.home> References: <20251218160925.3c02a721@gandalf.local.home> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Thu, 18 Dec 2025 16:09:25 -0500 Steven Rostedt wrote: > On Thu, 18 Dec 2025 09:53:16 -0800 > Alexei Starovoitov wrote: > > > > +static void bpf_kprobe_unregister(struct bpf_kprobe *kps, u32 cnt) > > > +{ > > > + for (int i = 0; i < cnt; i++) > > > + unregister_kretprobe(&kps[i].rp); > > > +} > > > > Nack. > > This is not a good idea. > > unregister_kretprobe() calls synchronize_rcu(). > > So the above loop will cause soft lockups for sure. > > Looks like it could be replaced with: > > unregister_kretprobes(kps, cnt); > > Which unregisters an array of kreptrobes and does a single > synchronize_rcu(). > > -- Steve Thanks for the suggestion. I will refactor the loop to use unregister_kretprobes() for a single RCU sync.