From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 2EC5C1F80C1 for ; Wed, 16 Oct 2024 08:32:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729067522; cv=none; b=p1vTsbFlKeC3sOU1JrfzWckRGyUe+K99p03gEHgkABnbbuWnGYnOvbWc7qlLStuNEw3FzmqkAidW007EMFp6gJRXGEX9rdxJKwpYIySuozFKI2MYsKqpH6icnPMn+Cb7vG4EjIpjtEBBaVw4il25qk16ffDi8OpKd9Ld288g0aw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729067522; c=relaxed/simple; bh=HochnkcnH4RaBRWXhxwwGqe2jFgJOCCoo6LbV74OU6M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jQAA/08/RDCBEDtg5qn+/0CzBQauagcPaSG52Il6XkHoWFeV5WktghP3NJJ2+4j5x/2hDqfBskc5PGMhTpA/pkyFQ/9jB8sP2VhVAY2LA5Xge/gnGj+ds2AoAi8UabqyvwgRcn/RiWUZd9jcBadUaeHAG4amhsLVzX80Ovq1uTA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=aksUMMQN; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aksUMMQN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1729067520; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Q6meqci1T/+gFr8r5uq6k+97j+u6uKiqkg4dUaqER0g=; b=aksUMMQN8tV/WtPhKbFIEM+tOrtvggxd+6MVtvEOagEsvSapnOeDTCm1/qfHH8QF2/YIxT 7CLvkHmswhb8pSSexLDdsWmktyyn/l5NSQpb0u2GxCID+bk4np7W8zIWHVoT9InO1gz2Xm jEsNB3cJuxi0QAfvLAsM3qJBW91AUiA= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-404-7BRDUEc-MzqHgT2XQqlMDg-1; Wed, 16 Oct 2024 04:31:57 -0400 X-MC-Unique: 7BRDUEc-MzqHgT2XQqlMDg-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6272619560AD; Wed, 16 Oct 2024 08:31:55 +0000 (UTC) Received: from fedora (unknown [10.72.116.176]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id DC1211956086; Wed, 16 Oct 2024 08:31:50 +0000 (UTC) Date: Wed, 16 Oct 2024 16:31:45 +0800 From: Ming Lei To: Christoph Hellwig Cc: linux-block@vger.kernel.org, Keith Busch , Jens Axboe , ming.lei@redhat.com Subject: Re: [Regression] b1a000d3b8ec ("block: relax direct io memory alignment") Message-ID: References: <20241016080419.GA30713@lst.de> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241016080419.GA30713@lst.de> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 On Wed, Oct 16, 2024 at 10:04:19AM +0200, Christoph Hellwig wrote: > On Wed, Oct 16, 2024 at 12:40:13AM +0800, Ming Lei wrote: > > Hello Guys, > > > > Turns out host controller's DMA alignment is often too relax, so two DMA > > buffers may cross same cache line easily, and trigger the warning of > > "cacheline tracking EEXIST, overlapping mappings aren't supported". > > > > The attached test code can trigger the warning immediately with CONFIG_DMA_API_DEBUG > > enabled when reading from one scsi disk which queue DMA alignment is 3. > > > > We should not allow smaller than cache line alignment on architectures > that are not cache coherent indeed. Yes, something like the following change: diff --git a/block/blk-settings.c b/block/blk-settings.c index a446654ddee5..26bd0e72c68e 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -348,7 +348,9 @@ static int blk_validate_limits(struct queue_limits *lim) */ if (!lim->dma_alignment) lim->dma_alignment = SECTOR_SIZE - 1; - if (WARN_ON_ONCE(lim->dma_alignment > PAGE_SIZE)) + else if (lim->dma_alignment < L1_CACHE_BYTES - 1) + lim->dma_alignment = L1_CACHE_BYTES - 1; + else if (WARN_ON_ONCE(lim->dma_alignment > PAGE_SIZE)) return -EINVAL; if (lim->alignment_offset) { Thanks, Ming