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From: Joao Martins <joao.m.martins@oracle.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org, dave.hansen@linux.intel.com, hch@lst.de,
	linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 11/12] device-dax: Add dis-contiguous resource support
Date: Tue, 12 May 2020 15:36:50 +0100	[thread overview]
Message-ID: <d7043cad-076d-d065-f933-b772b4e9c131@oracle.com> (raw)
In-Reply-To: <158500773552.2088294.8756587190550753100.stgit@dwillia2-desk3.amr.corp.intel.com>

On 3/23/20 11:55 PM, Dan Williams wrote:
> @@ -561,13 +580,26 @@ static int __alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
>  	if (start == U64_MAX)
>  		return -EINVAL;
>  
> +	ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
> +			* (dev_dax->nr_range + 1), GFP_KERNEL);
> +	if (!ranges)
> +		return -ENOMEM;
> +
>  	alloc = __request_region(res, start, size, dev_name(dev), 0);
> -	if (!alloc)
> +	if (!alloc) {
> +		kfree(ranges);
>  		return -ENOMEM;
> +	}

Noticed this yesterday while looking at alloc_dev_dax_range().

Is it correct to free @ranges here on __request_region failure?

IIUC krealloc() would free dev_dax->ranges if it succeeds, leaving us without
any valid ranges if __request_region failure case indeed frees @ranges. These
@ranges are being used afterwards when we delete the interface and free the
assigned regions. Perhaps we should remove the kfree() above and set
dev_dax->ranges instead before __request_region; or alternatively change the
call order between krealloc and __request_region? FWIW, krealloc checks if the
object being reallocated already meets the requested size, so perhaps there's no
harm with going with the former.

	Joao
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  parent reply	other threads:[~2020-05-12 14:37 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-23 23:54 [PATCH 00/12] device-dax: Support sub-dividing soft-reserved ranges Dan Williams
2020-03-23 23:54 ` [PATCH 01/12] device-dax: Drop the dax_region.pfn_flags attribute Dan Williams
2020-03-23 23:54 ` [PATCH 02/12] device-dax: Move instance creation parameters to 'struct dev_dax_data' Dan Williams
2020-03-23 23:54 ` [PATCH 03/12] device-dax: Make pgmap optional for instance creation Dan Williams
2020-03-23 23:54 ` [PATCH 04/12] device-dax: Kill dax_kmem_res Dan Williams
2020-03-23 23:55 ` [PATCH 05/12] device-dax: Add an allocation interface for device-dax instances Dan Williams
2020-03-23 23:55 ` [PATCH 06/12] device-dax: Introduce seed devices Dan Williams
2020-03-23 23:55 ` [PATCH 07/12] drivers/base: Make device_find_child_by_name() compatible with sysfs inputs Dan Williams
2020-03-23 23:55 ` [PATCH 08/12] device-dax: Add resize support Dan Williams
2020-03-23 23:55 ` [PATCH 09/12] mm/memremap_pages: Convert to 'struct range' Dan Williams
2020-03-23 23:55 ` [PATCH 10/12] mm/memremap_pages: Support multiple ranges per invocation Dan Williams
2020-03-23 23:55 ` [PATCH 11/12] device-dax: Add dis-contiguous resource support Dan Williams
2020-03-24 16:12   ` Joao Martins
2020-03-25 10:35     ` Joao Martins
2020-03-25 17:48       ` Dan Williams
2020-03-26 17:49         ` Joao Martins
2020-07-11  0:44     ` Dan Williams
2020-04-06 10:43   ` Joao Martins
2020-04-06 20:22     ` Dan Williams
2020-07-11  0:47       ` Dan Williams
2020-05-12 14:36   ` Joao Martins [this message]
2020-07-11  0:52     ` Dan Williams
2020-03-23 23:55 ` [PATCH 12/12] device-dax: Introduce 'mapping' devices Dan Williams
2020-03-24 16:27   ` Joao Martins
2020-03-24 23:51     ` Dan Williams

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