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b=IVOBb5xLR1QWeHHyFIp07pXoOjRkmb5kH1NbLK7HXNbjx7bAtJgGk1uxE1ho3RaSS FZrAX8RDckayMIYgBSLQmXglvM9NPhEy5Yhl5k8WbY0T2gk2Vk4OURTuQq1HqAKe3Y 30Wl9nEjJPf16sjghMpQ7nOcEnGDuijTHmFNNX5o= Date: Tue, 18 Aug 2026 20:26:56 -0700 From: Andrew Morton To: Foxie Flakey Cc: Mike Rapoport , Peter Xu , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] userfaultfd: reset err to be 0 when move_pages_ptes succeeded Message-Id: <20260818202656.f7a248b33f6130d06b4cf83e@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: qqsc9hmkkf6pm8jynojymkc7nf1hsyt8 X-Rspamd-Queue-Id: 9F94340007 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1787110018-589101 X-HE-Meta: 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 BR3Jk/ja G4uhzd9bGV6jCVvExoqi6tz3kw7tNItd7uJb1clbYn0emxt9RqKZEEXzHM4zUI/I1UnQhqOOGh1k7FPsGXIv/7Nn9YFsXJINPLGhVL3Uyz/31SQRWiVIJoDo7+itHexaGGtFhMcHXgmU3pHsrKpuHEgboe1Z0oxrP9dupvidRdIoUoNW1MVO7a+AVEIR9463bUsoOzDsDoNf9B9XPiwcVa7in/Ypn338KgqMbs+M+BH88hNjFk3Cky4RyHMUv9puT5N7jbdILbR69V32HvTO70Pz5qDwracjH27TLcAGa55c+6A/VvhRFpfXC/9Elif/Q7iWK Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 19 Aug 2026 10:08:24 +0700 (WIB) Foxie Flakey wrote: > > During move_pages() operation, when move_pages_ptes() returns EAGAIN, > the error code is not cleared even after we processed it. This leads > to a successful retry but then the same pages are retried again due to > the stale error code. This time move fails because pages are already > moved, loop is terminated and move_pages() reports a failure. > Clear the error code once we processes EAGAIN. > > Fixes: 50944692052b ("userfaultfd: opportunistic TLB-flush batching for present pages in MOVE") > Assisted-by: ChatGPT:GPT-5.6-Luna > Signed-off-by: Bryan Lim Thanks, Bryan. More paperwork: the signoff is supposed to match the Author:. The way to do this is to add an explicit From: line at start-of-changelog. If this is not present, we fall back to the email envelope's From:. > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -2085,8 +2085,10 @@ static ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start, > } > > if (err) { > - if (err == -EAGAIN) > + if (err == -EAGAIN) { > + err = 0; > continue; > + } > break; > } I'll queue it, with an adjusted From:, as above. Could reviewers please advise on whether we should backport this into -stable kernels?