All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: amit.pundir@linaro.org, hch@lst.de, linux-kernel@vger.kernel.org,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	rientjes@google.com, jeremy.linton@arm.com,
	linux-rpi-kernel@lists.infradead.org,
	iommu@lists.linux-foundation.org
Subject: Re: [PATCH v2 2/2] dma-pool: Only allocate from CMA when in same memory zone
Date: Tue, 4 Aug 2020 08:06:33 +0200	[thread overview]
Message-ID: <20200804060633.GA7368@lst.de> (raw)
In-Reply-To: <20200803160956.19235-3-nsaenzjulienne@suse.de>

On Mon, Aug 03, 2020 at 06:09:56PM +0200, Nicolas Saenz Julienne wrote:
> +	if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
> +		return end <= DMA_BIT_MASK(zone_dma_bits);
> +	if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
> +		return end <= DMA_BIT_MASK(32);
> +	if (gfp & GFP_KERNEL)
> +		return end > DMA_BIT_MASK(32);

So the GFP_KERNEL one here looks weird.  For one I don't think the if
line is needed at all, and it just confuses things.  Second I don't
see the need (and actually some harm) in preventing GFP_KERNEL
allocations from dipping into lower CMA areas - something that we did
support before 5.8 with the single pool.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: amit.pundir@linaro.org, linux-kernel@vger.kernel.org,
	jeremy.linton@arm.com, iommu@lists.linux-foundation.org,
	linux-rpi-kernel@lists.infradead.org, rientjes@google.com,
	Robin Murphy <robin.murphy@arm.com>,
	hch@lst.de
Subject: Re: [PATCH v2 2/2] dma-pool: Only allocate from CMA when in same memory zone
Date: Tue, 4 Aug 2020 08:06:33 +0200	[thread overview]
Message-ID: <20200804060633.GA7368@lst.de> (raw)
In-Reply-To: <20200803160956.19235-3-nsaenzjulienne@suse.de>

On Mon, Aug 03, 2020 at 06:09:56PM +0200, Nicolas Saenz Julienne wrote:
> +	if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
> +		return end <= DMA_BIT_MASK(zone_dma_bits);
> +	if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
> +		return end <= DMA_BIT_MASK(32);
> +	if (gfp & GFP_KERNEL)
> +		return end > DMA_BIT_MASK(32);

So the GFP_KERNEL one here looks weird.  For one I don't think the if
line is needed at all, and it just confuses things.  Second I don't
see the need (and actually some harm) in preventing GFP_KERNEL
allocations from dipping into lower CMA areas - something that we did
support before 5.8 with the single pool.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2020-08-04  6:06 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-03 16:09 [PATCH v2 0/2] dma-pool fixes Nicolas Saenz Julienne
2020-08-03 16:09 ` Nicolas Saenz Julienne
2020-08-03 16:09 ` [PATCH v2 1/2] dma-pool: fix coherent pool allocations for IOMMU mappings Nicolas Saenz Julienne
2020-08-03 16:09   ` Nicolas Saenz Julienne
2020-08-03 16:09 ` [PATCH v2 2/2] dma-pool: Only allocate from CMA when in same memory zone Nicolas Saenz Julienne
2020-08-03 16:09   ` Nicolas Saenz Julienne
2020-08-04  6:06   ` Christoph Hellwig [this message]
2020-08-04  6:06     ` Christoph Hellwig
2020-08-04  9:43     ` Nicolas Saenz Julienne
2020-08-04  9:43       ` Nicolas Saenz Julienne
2020-08-06  5:18       ` Christoph Hellwig
2020-08-06  5:18         ` Christoph Hellwig
2020-08-06 11:50         ` Nicolas Saenz Julienne
2020-08-06 11:50           ` Nicolas Saenz Julienne
2020-08-06 13:55           ` Christoph Hellwig
2020-08-06 13:55             ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200804060633.GA7368@lst.de \
    --to=hch@lst.de \
    --cc=amit.pundir@linaro.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jeremy.linton@arm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rpi-kernel@lists.infradead.org \
    --cc=m.szyprowski@samsung.com \
    --cc=nsaenzjulienne@suse.de \
    --cc=rientjes@google.com \
    --cc=robin.murphy@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.