From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) (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 63887396B98 for ; Sun, 2 Aug 2026 21:55:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785707720; cv=none; b=lza9Kg7lAUGkzipKRlRbC3OKpZHrByGNA30RxwcU5OVf1GG0XaC+g6NFelKC88nm4rpd1Ea2tKpTrWXqFpkAsUdYcvgaBoYL31KO+35JkLG2QXHzmA048DIsEEmUWp8Oqy16k8TywXtAryDZRr4xRZXNl2OmGGNvMDk8hmLriOQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785707720; c=relaxed/simple; bh=ehiROkTUONMb1XfowgmGCN5Etu/lait0K9h2IywdBVw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=XPaEHfjmTYsFsj64G/yH3n3g1P31Z0L73d0HhESSthEVROhJvE/HacVTeP/e7PQpvMUgHl8Q2RwRv/HR6ZayyFi2OQw0eOuk91Hrp23+RLzMvWNMqr8Ys0nmsC3nHvSRjLXE19EPjGSmMAiXbplvW3KzDutgBXIq07xChG9fPvk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--surenb.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=VMKyf0mU; arc=none smtp.client-ip=209.85.215.198 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=flex--surenb.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="VMKyf0mU" Received: by mail-pg1-f198.google.com with SMTP id 41be03b00d2f7-cb835525b10so3612111a12.2 for ; Sun, 02 Aug 2026 14:55:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1785707715; x=1786312515; darn=vger.kernel.org; h=content-transfer-encoding:content-type:cc:to:from:subject :message-id:references:mime-version:in-reply-to:date:from:to:cc :subject:date:message-id:reply-to:content-type; bh=FNzfa/Q2B0yr5cHe2iHTydpaM2L8dTGY4PL8h7AQ+vM=; b=VMKyf0mU/9SO7w/E6ybQZ4ENACjFKRDBksqBCXWpemQN/KzAMU5F1k1AzZKdmdL4vz GbT/eqY/LBIzayWtik7o6xGHolJrryrf/tBhI134vqW+kiWbLcwObmJqUzvLqEfCjHZD JiStzo6wdtLIxTNWKPrxXrpGcjJqaqG9r5LCfobm+nQMfJu+qV7vITkbsmPX7eFfw0pG eAy2UzVLQBjAK+m9t/nYBFSuHLYkUm+gnV5si98lNT7yefrnVrNbD80VO1B4srkHrsFH XOV854NmNpNzSaqjggq8zelePSasPHmOXnooOqoKmN4b5dCa4VcQg1hg7InlOtUZ9tak Fl3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785707715; x=1786312515; h=content-transfer-encoding:content-type:cc:to:from:subject :message-id:references:mime-version:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=FNzfa/Q2B0yr5cHe2iHTydpaM2L8dTGY4PL8h7AQ+vM=; b=gRrSZHfbsunuP9sFjSq08ZARepTPu0R3D+In5Aqy3NrcI7mVDA7w/ZoIUnK2HNa36L 7gnuNMn9ITI5BKBoCHnYBDECRPZgX5fBJaMRaFmCaznAGozh9Y7pXJPB8LV1ZUIbdPJi PthhCJO8czYTdhVo3dFePGhYWb4Z19CDRLxVlKzjMHc1LGQ0Hp/0e2F2bqrO2zmiZmUi iEtFj9kChT8G2i+awjVi4c8FsQNQwZfNjYincE1KQNrmDXrU/gBg9OcPvb6QJCNjpaaA eFJqH3SZYFbcjAeHfIT4gU0kAl7toat+bYVmxqcmm64+0d7aerTvKEZoOZ9/cM6TmCqo phEA== X-Forwarded-Encrypted: i=1; AHgh+RrILzoYTkPL8pY0sv0OVQrBimJzwmvbOp1mOC1LBBwGPLGYdI6iRST2Sbc+uDzKs77pBNydkwRFHG+WfFk=@vger.kernel.org X-Gm-Message-State: AOJu0YycJNInDvZbn7An+pnIMhsqlq7uKDw5r9CTxesm1t0aiIkoMKWT z/HLQjz1WS9VRTTOeVfCujwPJxSYppt9wvOfNICPUgo0c39qsQmKulCbOWf8NFxASOYjskeu9xD 7G876Iw== X-Received: from dlep14-n1.prod.google.com ([2002:a05:701b:458e:10b0:13d:2928:7996]) (user=surenb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:d80f:b0:3ba:cd5b:3dc8 with SMTP id adf61e73a8af0-3c92a5f1c89mr7273098637.31.1785707714551; Sun, 02 Aug 2026 14:55:14 -0700 (PDT) Date: Sun, 2 Aug 2026 14:54:59 -0700 In-Reply-To: <20260802215459.2769283-1-surenb@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260802215459.2769283-1-surenb@google.com> X-Mailer: git-send-email 2.55.0.508.g3f0d502094-goog Message-ID: <20260802215459.2769283-6-surenb@google.com> Subject: [PATCH v3 5/5] tcp: Remove mmap_lock fallback path From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: dave.hansen@linux.intel.com, Liam.Howlett@oracle.com, ljs@kernel.org, david@redhat.com, willy@infradead.org, shakeel.butt@linux.dev, vbabka@kernel.org, jannh@google.com, aliceryhl@google.com, arve@android.com, cmllamas@google.com, christian@brauner.io, tkjos@android.com, dsahern@kernel.org, davem@davemloft.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, surenb@google.com, syzbot@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable From: Dave Hansen Previously, the per-VMA locking could fail in the face of writers which necessitates a fallback to mmap_lock. The new lock_vma_under_rcu_wait() will wait for writers instead of failing. Use the new helper. Wait for writers. Remove the fallback to mmap_lock. This really is a nice cleanup. It removes the need to pass the lock state back and forth to find_tcp_vma(). Signed-off-by: Dave Hansen Signed-off-by: Suren Baghdasaryan Acked-by: Lorenzo Stoakes Acked-by: Vlastimil Babka (SUSE) Tested-by: syzbot@syzkaller.appspotmail.com Cc: Andrew Morton Cc: Liam R. Howlett Cc: Vlastimil Babka Cc: Shakeel Butt Cc: linux-mm@kvack.org Cc: Greg Kroah-Hartman Cc: Arve Hj=C3=B8nnev=C3=A5g Cc: Todd Kjos Cc: Christian Brauner Cc: Carlos Llamas Cc: Alice Ryhl Cc: David S. Miller Cc: David Ahern Cc: netdev@vger.kernel.org --- net/ipv4/tcp.c | 31 +++++++++---------------------- 1 file changed, 9 insertions(+), 22 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 455441f1b694..62defe70f3ce 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2167,27 +2167,18 @@ static void tcp_zc_finalize_rx_tstamp(struct sock *= sk, } =20 static struct vm_area_struct *find_tcp_vma(struct mm_struct *mm, - unsigned long address, - bool *mmap_locked) + unsigned long address) { - struct vm_area_struct *vma =3D lock_vma_under_rcu(mm, address); + struct vm_area_struct *vma =3D vma_start_read_unlocked(mm, address); =20 - if (vma) { - if (vma->vm_ops !=3D &tcp_vm_ops) { - vma_end_read(vma); - return NULL; - } - *mmap_locked =3D false; - return vma; - } + if (!vma) + return NULL; =20 - mmap_read_lock(mm); - vma =3D vma_lookup(mm, address); - if (!vma || vma->vm_ops !=3D &tcp_vm_ops) { - mmap_read_unlock(mm); + if (vma->vm_ops !=3D &tcp_vm_ops) { + vma_end_read(vma); return NULL; } - *mmap_locked =3D true; + return vma; } =20 @@ -2208,7 +2199,6 @@ static int tcp_zerocopy_receive(struct sock *sk, u32 seq =3D tp->copied_seq; u32 total_bytes_to_map; int inq =3D tcp_inq(sk); - bool mmap_locked; int ret; =20 zc->copybuf_len =3D 0; @@ -2233,7 +2223,7 @@ static int tcp_zerocopy_receive(struct sock *sk, return 0; } =20 - vma =3D find_tcp_vma(current->mm, address, &mmap_locked); + vma =3D find_tcp_vma(current->mm, address); if (!vma) return -EINVAL; =20 @@ -2315,10 +2305,7 @@ static int tcp_zerocopy_receive(struct sock *sk, zc, total_bytes_to_map); } out: - if (mmap_locked) - mmap_read_unlock(current->mm); - else - vma_end_read(vma); + vma_end_read(vma); /* Try to copy straggler data. */ if (!ret) copylen =3D tcp_zc_handle_leftover(zc, sk, skb, &seq, copybuf_len, tss); --=20 2.55.0.508.g3f0d502094-goog