From: Mike Rapoport <rppt@kernel.org>
To: Peter Xu <peterx@redhat.com>
Cc: David CARLIER <devnexen@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@kernel.org>
Subject: Re: [PATCH v4] mm/userfaultfd: detect VMA replacement after copy retry in mfill_copy_folio_retry()
Date: Thu, 2 Apr 2026 07:02:40 +0300 [thread overview]
Message-ID: <ac3qYA40OW29ibbq@kernel.org> (raw)
In-Reply-To: <ac1wW6LHzzkXBeSl@x1.local>
On Wed, Apr 01, 2026 at 03:22:03PM -0400, Peter Xu wrote:
>
> The other thing is I just noticed the err code was changed to -EINVAL for
> snapshot changed cases, sorry I didn't follow previously as closely on the
> discussion. I think it should be -EAGAIN. It's because the userapp can't
> resolve -EINVAL failures and app will crash. In a VMA change use case, we
> should return -EAGAIN to imply the app to retry, rather than crashing.
No. The return value should express that the VMA is invalid. -EINVAL could
work, but looking now at the manual -ENOENT would be even better:
ENOENT (since Linux 4.11)
The faulting process has changed its virtual memory layout
simultaneously with an outstanding UFFDIO_COPY operation.
> Thanks,
> --
> Peter Xu
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2026-04-02 4:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-31 13:41 [PATCH v4] mm/userfaultfd: detect VMA replacement after copy retry in mfill_copy_folio_retry() David Carlier
2026-04-01 3:01 ` Andrew Morton
2026-04-01 7:49 ` Mike Rapoport
2026-04-01 8:06 ` David CARLIER
2026-04-01 15:23 ` Peter Xu
2026-04-01 18:34 ` David CARLIER
2026-04-01 19:22 ` Peter Xu
2026-04-01 20:05 ` David CARLIER
2026-04-02 4:02 ` Mike Rapoport [this message]
2026-04-02 5:59 ` David CARLIER
2026-04-02 13:29 ` Peter Xu
2026-04-09 11:20 ` Mike Rapoport
2026-04-10 15:10 ` Peter Xu
2026-04-02 3:58 ` Mike Rapoport
2026-04-02 13:42 ` Peter Xu
2026-04-09 11:31 ` Mike Rapoport
2026-04-10 15:26 ` Peter Xu
2026-04-12 15:46 ` Mike Rapoport
2026-04-13 12:53 ` Peter Xu
2026-04-07 10:17 ` Lorenzo Stoakes (Oracle)
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