From: Christoph Hellwig <hch@lst.de>
To: Chen Yu <yu.c.chen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
Baolu Lu <baolu.lu@intel.com>, Kevin Tian <kevin.tian@intel.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dma-direct: fix the page free when it is not addressable
Date: Tue, 3 Sep 2024 09:35:21 +0200 [thread overview]
Message-ID: <20240903073521.GA2269@lst.de> (raw)
In-Reply-To: <20240831110119.200377-1-yu.c.chen@intel.com>
On Sat, Aug 31, 2024 at 07:01:19PM +0800, Chen Yu wrote:
> When the CMA allocation succeeds but isn't addressable, its
> buffer has already been released and the page is set to NULL.
> So later when the normal page allocation succeeds but isn't
> addressable, __free_pages() should be used to free that normal
> page rather than freeing continuous page(CMA).
So the patch is obviously correct and probably useful, but I don't think
the existing code is buggy.
dma_free_contiguous calls into cma_release, which uses cma_pages_valid to
check if the page belongs to the CMA pool and retuns early if not,
letting dma_free_contiguous fall back to __free_pages eventually.
What am I missing here?
next prev parent reply other threads:[~2024-09-03 7:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-31 11:01 [PATCH] dma-direct: fix the page free when it is not addressable Chen Yu
2024-09-03 7:35 ` Christoph Hellwig [this message]
2024-09-03 8:00 ` Chen Yu
2024-09-03 8:02 ` Christoph Hellwig
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