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Date:   Thu, 5 Aug 2021 09:43:33 +0300
From:   Leon Romanovsky <leon@kernel.org>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Li Zhijian <lizhijian@cn.fujitsu.com>, dledford@redhat.com,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] RDMA/mlx5: return the EFAULT per ibv_advise_mr(3)
Message-ID: <YQuIlUT9jZLeFPNH@unreal>
References: <20210801092050.6322-1-lizhijian@cn.fujitsu.com>
 <20210803162507.GA2892108@nvidia.com>
 <YQmDZpbCy3uTS5jv@unreal>
 <20210803181341.GE1721383@nvidia.com>
 <YQonIu3VMTlGj0TJ@unreal>
 <20210804185022.GM1721383@nvidia.com>
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On Wed, Aug 04, 2021 at 03:50:22PM -0300, Jason Gunthorpe wrote:
> On Wed, Aug 04, 2021 at 08:35:30AM +0300, Leon Romanovsky wrote:
> > On Tue, Aug 03, 2021 at 03:13:41PM -0300, Jason Gunthorpe wrote:
> > > On Tue, Aug 03, 2021 at 08:56:54PM +0300, Leon Romanovsky wrote:
> > > > On Tue, Aug 03, 2021 at 01:25:07PM -0300, Jason Gunthorpe wrote:
> > > > > On Sun, Aug 01, 2021 at 05:20:50PM +0800, Li Zhijian wrote:
> > > > > > ibv_advise_mr(3) says:
> > > > > > EFAULT In one of the following: o When the range requested is out of the  MR  bounds,
> > > > > >        or  when  parts of it are not part of the process address space. o One of the
> > > > > >        lkeys provided in the scatter gather list is invalid or with wrong write access
> > > > > > 
> > > > > > Actually get_prefetchable_mr() will return NULL if it see above conditions
> > > > > 
> > > > > No, get_prefetchable_mr() returns NULL if the mkey is invalid
> > > > 
> > > > And what is this?
> > > >   1701 static struct mlx5_ib_mr *                         
> > > >   1702 get_prefetchable_mr(struct ib_pd *pd, enum ib_uverbs_advise_mr_advice advice,
> > > >   1703                     u32 lkey)
> > > > 
> > > > ...
> > > > 
> > > >   1721         /* prefetch with write-access must be supported by the MR */
> > > >   1722         if (advice == IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH_WRITE &&
> > > >   1723             !mr->umem->writable) {
> > > >   1724                 mr = NULL;
> > > >   1725                 goto end;
> > > >   1726         }
> > > 
> > > I would say that is an invalid mkey
> > 
> > I see it is as wrong write access.
> 
> It just means the man page is wrong

ok, it can be a solution too.

Thanks

> 
> Jason