linux-nvdimm.lists.01.org archive mirror
 help / color / mirror / Atom feed
From: Dan Williams <dan.j.williams@intel.com>
To: Joao Martins <joao.m.martins@oracle.com>
Cc: Linux MM <linux-mm@kvack.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 11/12] device-dax: Add dis-contiguous resource support
Date: Fri, 10 Jul 2020 17:52:50 -0700	[thread overview]
Message-ID: <CAPcyv4ie3pavOzPP68jGdeT1UK2eMjiZwiwvw1Jzy6D-d_pxjg@mail.gmail.com> (raw)
In-Reply-To: <d7043cad-076d-d065-f933-b772b4e9c131@oracle.com>

On Tue, May 12, 2020 at 7:37 AM Joao Martins <joao.m.martins@oracle.com> wrote:
>
> 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.

Yeah, the kfree is bogus. It can just wait until the device is
destroyed to be freed, but only if there is an existing allocation. If
this is a new allocation then nothing else will do the kfree.
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

  reply	other threads:[~2020-07-11  0:53 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
2020-07-11  0:52     ` Dan Williams [this message]
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

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=CAPcyv4ie3pavOzPP68jGdeT1UK2eMjiZwiwvw1Jzy6D-d_pxjg@mail.gmail.com \
    --to=dan.j.williams@intel.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=hch@lst.de \
    --cc=joao.m.martins@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-nvdimm@lists.01.org \
    --subject='Re: [PATCH 11/12] device-dax: Add dis-contiguous resource support' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).