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From: wangyunjian <wangyunjian@huawei.com>
To: Thomas Monjalon <thomas@monjalon.net>, "anatoly.burakov@intel.com"
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Thread-Topic: [dpdk-stable] [dpdk-dev] [PATCH v3] eal: fix create user mem
 map repeatedly when it exists
Thread-Index: AQHWo57F7aOjtaNYVkifJCCXNTgsH6mgB8gAgCjglwCAC0J9gIABZLFQ
Date: Mon, 23 Nov 2020 07:40:33 +0000
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Subject: Re: [dpdk-dev] [dpdk-stable] [PATCH v3] eal: fix create user mem
 map repeatedly when it exists
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> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Monday, November 23, 2020 2:20 AM
> To: anatoly.burakov@intel.com; wangyunjian <wangyunjian@huawei.com>
> Cc: stable@dpdk.org; dev@dpdk.org; david.marchand@redhat.com; Lilijun
> (Jerry) <jerry.lilijun@huawei.com>; xudingke <xudingke@huawei.com>;
> bruce.richardson@intel.com; john.mcnamara@intel.com; asafp@nvidia.com
> Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH v3] eal: fix create user mem=
 map
> repeatedly when it exists
>=20
> 15/11/2020 15:23, Thomas Monjalon:
> > 20/10/2020 16:09, Thomas Monjalon:
> > > 16/10/2020 11:28, wangyunjian:
> > > > From: Yunjian Wang <wangyunjian@huawei.com>
> > > >
> > > > Currently, a issue that a container has many devices and the
> > > > application will map the same memory many times. The kernel driver
> > > > returns EEXIST as long as there are overlapping memory areas. As a
> > > > result, we repeatedly create new user mem map entry for the same
> > > > memory segment and this will lead to no more space for other user
> > > > mem maps.
> > > >
> > > > To resolve the issue, add support to remove the same entry in the
> > > > function compact_user_maps().
> > >
> > > Sorry I don't understand the explanations above.
> > > Anatoly, please could you help in rewording?
> >
> > Ping for rewording please.
>=20
> What is the conclusion? This fix is not worth the effort?
>=20

In my opinion, this issue needs to be fixed. Currently, the 'user_mem_maps-=
>maps[]'
may store many same user mem maps but the maps array is limited, which will=
 lead
to other mem maps cannot be created because of no more space left.

Thanks,
Yunjian