From: John Hubbard <jhubbard@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>, Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-rdma@vger.kernel.org, linux-mm@kvack.org,
Mike Marciniszyn <mike.marciniszyn@intel.com>,
Leon Romanovsky <leon@kernel.org>,
Artemy Kovalyov <artemyko@nvidia.com>,
Michael Guralnik <michaelgur@nvidia.com>,
Alistair Popple <apopple@nvidia.com>,
Pak Markthub <pmarkthub@nvidia.com>
Subject: Re: [RFC] RDMA/umem: pin_user_pages*() can temporarily fail due to migration glitches
Date: Wed, 1 May 2024 10:32:38 -0700 [thread overview]
Message-ID: <8767cde0-0ae5-4532-9460-90960bc40eef@nvidia.com> (raw)
In-Reply-To: <20240501121032.GA941030@nvidia.com>
On 5/1/24 5:10 AM, Jason Gunthorpe wrote:
> On Tue, Apr 30, 2024 at 10:10:43PM -0700, Christoph Hellwig wrote:
...
>> This doesn't make sense. IFF a blind retry is all that is needed it
>> should be done in the core functionality. I fear it's not that easy,
>> though.
So do I. :)
>
> +1
>
> This migration retry weirdness is a GUP issue, it needs to be solved
> in the mm not exposed to every pin_user_pages caller.
>
> If it turns out ZONE_MOVEABLE pages can't actually be reliably moved
> then it is pretty broken..
>
OK, I'll work on finding out what is temporarily elevating the refcount
and preventing the migration. And see where that leads.
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2024-05-01 17:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-01 0:31 [RFC] RDMA/umem: pin_user_pages*() can temporarily fail due to migration glitches John Hubbard
2024-05-01 5:10 ` Christoph Hellwig
2024-05-01 12:10 ` Jason Gunthorpe
2024-05-01 17:32 ` John Hubbard [this message]
2024-05-02 1:05 ` Alistair Popple
2024-05-02 6:49 ` John Hubbard
2024-05-02 6:56 ` David Hildenbrand
2024-05-02 18:10 ` John Hubbard
2024-05-02 18:34 ` Jason Gunthorpe
2024-05-02 18:44 ` Matthew Wilcox
2024-05-10 7:54 ` David Hildenbrand
2024-05-11 0:32 ` Kasireddy, Vivek
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