From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) (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 2EBE1336885; Wed, 10 Jun 2026 23:04:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781132663; cv=none; b=Urw1Lb+jM3hqxD5uP2I23ei5RfE5qwoc7A1FZnSuHQevJtWMqzEaLTSNHNzkSbehR0JmYpDJjcRX4lQlB265GHwzmBzkYbrcTqVGNgcCYwgiBMm/DzQxJq5Z/p04cOSDsAEw4jkNu3xMsSQ8vKDDs97p3q7SSO3jJJdGaA7Alao= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781132663; c=relaxed/simple; bh=19BDK6BwhTcrHnLv8z8OKRfT+e/osIT4EuXdhKNAOnI=; h=Subject:To:Cc:From:Date:References:In-Reply-To:Message-Id; b=LeSBl3ZLehAd1V71FikEYtchEODwssA2XWnoX2LgpL1RKzjHt+P404epJCj7TAhQA/NZze7RaSX/Vjl6v5mpYZgolJfXMP+/8I7/fxcXTeeNy3pytoXfvRQQQgAPmiGZHkswJd7TlDm1vERBHSudbQJkwB6PEG9WNgyITb6Yuvw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=hGjF75fm; arc=none smtp.client-ip=192.198.163.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="hGjF75fm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1781132661; x=1812668661; h=subject:to:cc:from:date:references:in-reply-to: message-id; bh=19BDK6BwhTcrHnLv8z8OKRfT+e/osIT4EuXdhKNAOnI=; b=hGjF75fmLba8sDPFoag1qtULw3jGf/Cn6bd/2ljXMC2I4PZEjM2lGv4j pIxRhZF8VM7+BaZS5lC9rc+5vhgtXxK1RZdrWS8mq8edR6wUpppu+myOX YkB2nn7liGpfcjIDxJdOdunhCwixX8AJZ1i9JlMM+NpNpWbutDdmo8CFO lflhwGNv+Yy+HsoBpT7J28A5GMD88biuku5uINeS1dm3yziMGgZCrCmzV wgDG+48+yoHLhGder5xZvduilQQSeRHzKJBjUct+1Q2m+v2wAlQd7JC4l VVaVco4gwcEtYASyqe07n+L8g/X9nZL5pblqBjutLFktvt8NQ5UBOn8iU g==; X-CSE-ConnectionGUID: rtPwktqSS3e5ElvhiXfChw== X-CSE-MsgGUID: cu6I0EV1TgKplS/4VDvc5w== X-IronPort-AV: E=McAfee;i="6800,10657,11813"; a="81074128" X-IronPort-AV: E=Sophos;i="6.24,197,1774335600"; d="scan'208";a="81074128" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jun 2026 16:04:20 -0700 X-CSE-ConnectionGUID: aXawu264TMWGTsm2tch8Qw== X-CSE-MsgGUID: m2ctBtL5SS6Rmntdy+Cwzg== X-ExtLoop1: 1 Received: from davehans-spike.ostc.intel.com (HELO localhost.localdomain) ([10.165.164.11]) by fmviesa003.fm.intel.com with ESMTP; 10 Jun 2026 16:04:19 -0700 Subject: [PATCH v2 5/5] tcp: Remove mmap_lock fallback path To: linux-kernel@vger.kernel.org Cc: Dave Hansen , Alice Ryhl , Andrew Morton , Arve Hjønnevåg , Carlos Llamas , Christian Brauner , David Ahern , "David S. Miller" , Greg Kroah-Hartman , "Liam R. Howlett" , linux-mm@kvack.org, Lorenzo Stoakes , netdev@vger.kernel.org, Shakeel Butt , Suren Baghdasaryan , Todd Kjos , Vlastimil Babka From: Dave Hansen Date: Wed, 10 Jun 2026 16:04:19 -0700 References: <20260610230409.A44D29FA@davehans-spike.ostc.intel.com> In-Reply-To: <20260610230409.A44D29FA@davehans-spike.ostc.intel.com> Message-Id: <20260610230419.F746395F@davehans-spike.ostc.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 Acked-by: Lorenzo Stoakes Reviewed-by: Suren Baghdasaryan Cc: Andrew Morton Cc: "Liam R. Howlett" Cc: Vlastimil Babka Cc: Shakeel Butt Cc: linux-mm@kvack.org Cc: Greg Kroah-Hartman Cc: Arve Hjønnevåg Cc: Todd Kjos Cc: Christian Brauner Cc: Carlos Llamas Cc: Alice Ryhl Cc: "David S. Miller" Cc: David Ahern Cc: netdev@vger.kernel.org --- b/net/ipv4/tcp.c | 31 +++++++++---------------------- 1 file changed, 9 insertions(+), 22 deletions(-) diff -puN net/ipv4/tcp.c~ipv4-tcp-vma-waiter net/ipv4/tcp.c --- a/net/ipv4/tcp.c~ipv4-tcp-vma-waiter 2026-06-10 15:57:56.972472379 -0700 +++ b/net/ipv4/tcp.c 2026-06-10 15:57:56.976472521 -0700 @@ -2171,27 +2171,18 @@ static void tcp_zc_finalize_rx_tstamp(st } 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 = lock_vma_under_rcu(mm, address); + struct vm_area_struct *vma = vma_start_read_unlocked(mm, address); - if (vma) { - if (vma->vm_ops != &tcp_vm_ops) { - vma_end_read(vma); - return NULL; - } - *mmap_locked = false; - return vma; - } + if (!vma) + return NULL; - mmap_read_lock(mm); - vma = vma_lookup(mm, address); - if (!vma || vma->vm_ops != &tcp_vm_ops) { - mmap_read_unlock(mm); + if (vma->vm_ops != &tcp_vm_ops) { + vma_end_read(vma); return NULL; } - *mmap_locked = true; + return vma; } @@ -2212,7 +2203,6 @@ static int tcp_zerocopy_receive(struct s u32 seq = tp->copied_seq; u32 total_bytes_to_map; int inq = tcp_inq(sk); - bool mmap_locked; int ret; zc->copybuf_len = 0; @@ -2237,7 +2227,7 @@ static int tcp_zerocopy_receive(struct s return 0; } - vma = find_tcp_vma(current->mm, address, &mmap_locked); + vma = find_tcp_vma(current->mm, address); if (!vma) return -EINVAL; @@ -2319,10 +2309,7 @@ static int tcp_zerocopy_receive(struct s 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 = tcp_zc_handle_leftover(zc, sk, skb, &seq, copybuf_len, tss); _