From: John Hubbard <jhubbard@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>,
linux-mm@kvack.org, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, "Sierra Guiza,
Alejandro (Alex)" <alex.sierra@amd.com>,
Chaitanya Kulkarni <kch@nvidia.com>,
Dan Williams <dan.j.williams@intel.com>,
Felix Kuehling <Felix.Kuehling@amd.com>,
Logan Gunthorpe <logang@deltatee.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Muchun Song <songmuchun@bytedance.com>,
Ralph Campbell <rcampbell@nvidia.com>,
David Hildenbrand <david@redhat.com>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v4 2/2] mm/gup.c: Refactor check_and_migrate_movable_pages()
Date: Wed, 17 Aug 2022 16:05:47 -0700 [thread overview]
Message-ID: <20370ebb-8e63-2065-307a-81fa874eced2@nvidia.com> (raw)
In-Reply-To: <Yv1wntznpzSXuTYh@nvidia.com>
On 8/17/22 15:50, Jason Gunthorpe wrote:
>
> But why return 0 from the helper function in the first place?
>
The caller is looking for three distinct return code cases: 0, -EAGAIN,
or some other -errno. Unless you restructure more, you need all three
of those cases. The 0 case leads to the caller, __gup_longterm_locked,
returning nr_pages.
Here is the comment block that I recommended earlier in this thread, that
documents those cases:
https://lore.kernel.org/r/dc8fd102-ba30-d980-bdbb-11f39326103d@nvidia.com
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2022-08-17 23:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-12 2:13 [PATCH v4 1/2] mm/gup.c: Don't pass gup_flags to check_and_migrate_movable_pages() Alistair Popple
2022-08-12 2:13 ` [PATCH v4 2/2] mm/gup.c: Refactor check_and_migrate_movable_pages() Alistair Popple
2022-08-12 7:05 ` John Hubbard
2022-08-15 16:15 ` Jason Gunthorpe
2022-08-16 5:29 ` Alistair Popple
2022-08-16 11:29 ` Jason Gunthorpe
2022-08-17 2:01 ` Alistair Popple
2022-08-17 12:09 ` Jason Gunthorpe
2022-08-17 20:35 ` John Hubbard
2022-08-17 22:50 ` Jason Gunthorpe
2022-08-17 23:05 ` John Hubbard [this message]
2022-08-17 23:24 ` Alistair Popple
2022-08-17 23:40 ` Jason Gunthorpe
2022-08-12 12:57 ` [PATCH v4 1/2] mm/gup.c: Don't pass gup_flags to check_and_migrate_movable_pages() Matthew Wilcox
2022-08-12 18:02 ` John Hubbard
2022-08-12 18:11 ` Matthew Wilcox
2022-08-15 5:52 ` Alistair Popple
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