From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f170.google.com (mail-qt1-f170.google.com [209.85.160.170]) (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 8FBEF1D0486 for ; Fri, 11 Oct 2024 19:38:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728675511; cv=none; b=qSavJOTFElIWMDO/gz3owuPMiL5hw0DbYgU/z9U/ALBK90xARqAiFpHej05j2UiZUWLlcg1VGj0YxOOv0T/18YRIiqr74w5QtB5c52CNy0d929NkzHOBRd/tjzfoblDqtTPEsP0gkTvE4wHbw/UTnuYqaYZs/SsWQ1rKwsoIVWc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728675511; c=relaxed/simple; bh=lIT4MF3P08EUQ/ItxiJCyTg8JaALptzUPgWCabDCkKc=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=nLkQDT1zO2F/LQ6ydGiTT5ggwDJTPNca3ASmq0gDtCQIhWWONqpBfdcsSroT5frzF1pEB5ytMAnqoYHPfmNmKT5SWNR051QRdgXSp8Up8Vy+Js1w2wdTJpU6wLx8v1HYHAV2rq8gexL8Q+NK83k76Cdp6xxrsPzdroqWWwh7y4I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=XjkjknEt; arc=none smtp.client-ip=209.85.160.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="XjkjknEt" Received: by mail-qt1-f170.google.com with SMTP id d75a77b69052e-4603d3e0547so40541cf.0 for ; Fri, 11 Oct 2024 12:38:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1728675507; x=1729280307; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=f4/PPqatSk2BAD8kUIT/38Gyd1BY7fTrP7ap/2S9Mqk=; b=XjkjknEt5tftq70KCGlTHLD1Bh2BPjVE2PxpnBWMyyvy0Sp3gh+Ou2AGHu9p3dWutG Ly3++jhiM30xrysorDSmgJ1/CrEZtf6ayIU3Zmwx3Vb8IUgL3FRRSfyF9Uq+Uzbj3vUN u/bUYraAbm5jodAmY4pqow/Khq+dr2J2OnWFkAw+h8J7APJ1G+1llNpGccZsVYLd3rvD +QBQRdyuhuBJG6aMG9ikacbC88xyvg5Opx9d5h6aw4PuP1rE87zMIrrAmpxqP3AFOGuK ExS8+5YeQleDH4F25vvvICWGh0gbjOcW75+6kisVvnRm7+3uDYn2SyaicjpmO643m7Cu Y50g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728675507; x=1729280307; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=f4/PPqatSk2BAD8kUIT/38Gyd1BY7fTrP7ap/2S9Mqk=; b=c4nTFTE/D8cnPPkaYL1ESO3WuPKsRopyaqBC28f2FjRvF2UqMQtxS0ZfgWOueqa2el sWu4pf4et6kEpqVO/Vf5+q0hwc0I0Rs94QyA2wsFQil5FYrV0fzamgEKYeoLICNQ/F0n LndxsTZcC49NpNLL0M6giEqs2x4U+D6yuHIL2KN8Gjcy88Zn9gWUOHACe5g+bzlQ8HSr BmUZS3hZqgr2njuaUUM8IxqrG8/hKmMjgojwOIMikFjOau+6J9xnJrOxSVsJSYYUS/xL XD9KnFYnW/5s8jN+Y0AbKu3VM061x3oQ6odOICHxPTm6LzUS3FXeYTLZLjrIZo6Z7B+Y EZNg== X-Forwarded-Encrypted: i=1; AJvYcCW8FlBal6/DNapQ8WZ2s9FA+gz93xHpa7w3Hfbkw6Pv7+O75o0yli0sQ6wNnY6jiJRvslWzE+ZtX8P1v8VBZRskSxw=@vger.kernel.org X-Gm-Message-State: AOJu0YyLhwRNQKbPQaoXnRkwAJjBA4Sc/FJXWdER06xv1wjoakwFwv6B 8tOO4tAh0fcU349vQ7xbvyBUa4SZCyKW1GrvaBiYiRHWuV8S4UlZXkgSzHwOSd4/RnwCoc+6X3+ 0pVyIF4tQuwWJ2+sjl5xglQWQgY4hD7rslKBG X-Google-Smtp-Source: AGHT+IEJvq2uzdDh3W2Sfu5aWaK5xhLaKiCn2xWH/iIRkxgpB4FklAs+UX9kaTQ1TkS7P0dLyhTRAOjn/li4z+5WdqQ= X-Received: by 2002:a05:622a:468c:b0:45c:9eab:cce0 with SMTP id d75a77b69052e-46059046571mr529141cf.15.1728675507274; Fri, 11 Oct 2024 12:38:27 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240909054318.1809580-1-almasrymina@google.com> <20240909054318.1809580-11-almasrymina@google.com> <20241011082707.5de66f15@kernel.org> In-Reply-To: <20241011082707.5de66f15@kernel.org> From: Mina Almasry Date: Fri, 11 Oct 2024 12:38:14 -0700 Message-ID: Subject: Re: [PATCH net-next v25 10/13] net: add SO_DEVMEM_DONTNEED setsockopt to release RX frags To: Jakub Kicinski Cc: "Lai, Yi" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-arch@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, Donald Hunter , "David S. Miller" , Eric Dumazet , Paolo Abeni , Jonathan Corbet , Richard Henderson , Ivan Kokshaysky , Matt Turner , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Andreas Larsson , Jesper Dangaard Brouer , Ilias Apalodimas , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Arnd Bergmann , Steffen Klassert , Herbert Xu , David Ahern , Willem de Bruijn , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Magnus Karlsson , Maciej Fijalkowski , Jonathan Lemon , Shuah Khan , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Pavel Begunkov , David Wei , Jason Gunthorpe , Yunsheng Lin , Shailend Chand , Harshitha Ramamurthy , Shakeel Butt , Jeroen de Borst , Praveen Kaligineedi , Bagas Sanjaya , Christoph Hellwig , Nikolay Aleksandrov , Taehee Yoo , Willem de Bruijn , Kaiyuan Zhang , yi1.lai@intel.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Oct 11, 2024 at 8:27=E2=80=AFAM Jakub Kicinski wr= ote: > > On Thu, 10 Oct 2024 12:05:38 -0700 Mina Almasry wrote: > > diff --git a/net/core/sock.c b/net/core/sock.c > > index 083d438d8b6f..cb3d8b19de14 100644 > > --- a/net/core/sock.c > > +++ b/net/core/sock.c > > @@ -1071,11 +1071,11 @@ sock_devmem_dontneed(struct sock *sk, > > sockptr_t optval, unsigned int optlen) > > optlen > sizeof(*tokens) * MAX_DONTNEED_TOKENS) > > return -EINVAL; > > > > - tokens =3D kvmalloc_array(optlen, sizeof(*tokens), GFP_KERNEL); > > + num_tokens =3D optlen / sizeof(struct dmabuf_token); > > + tokens =3D kvmalloc_array(num_tokens, sizeof(*tokens), GFP_KERN= EL); > > if (!tokens) > > return -ENOMEM; > > > > - num_tokens =3D optlen / sizeof(struct dmabuf_token); > > if (copy_from_sockptr(tokens, optval, optlen)) { > > kvfree(tokens); > > return -EFAULT; > > @@ -1083,6 +1083,10 @@ sock_devmem_dontneed(struct sock *sk, sockptr_t > > optval, unsigned int optlen) > > > > xa_lock_bh(&sk->sk_user_frags); > > for (i =3D 0; i < num_tokens; i++) { > > + > > + if (tokens[i].token_count > MAX_DONTNEED_TOKENS) > > + continue; > > For the real fix let's scan the tokens before we take the xa lock > and return an error rather than silently skipping? > > > for (j =3D 0; j < tokens[i].token_count; j++) { > Yes, sorry, I called the diff above an 'untested fix' but it was more of a hack to see if I got the root cause right. For a proper fix, we should do exactly that. Scan and see how many tokens the user is asking us to free ahead of time, then exit early if it's too much before we acquire locks and loop. Will do! --=20 Thanks, Mina