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Tue, 18 Aug 2026 20:42:50 -0700 (PDT) From: Foxie Flakey X-Google-Original-From: Foxie Flakey Date: Wed, 19 Aug 2026 10:42:46 +0700 (WIB) To: Andrew Morton 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 In-Reply-To: <20260818202656.f7a248b33f6130d06b4cf83e@linux-foundation.org> Message-ID: References: <20260818202656.f7a248b33f6130d06b4cf83e@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 18CC8180003 X-Stat-Signature: j1ks39gcssccu7r7jghqq8ihmp1m59cy X-Rspam-User: X-HE-Tag: 1787110971-376231 X-HE-Meta: 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 81yeDzl8 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 18 Aug 2026, Andrew Morton wrote: > 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. No, problem. Thank you for your time. If you don't mind this, I would prefer keep to be called as Foxie unless its required to be Bryan Lim like the sign off. Sorry, if it took a while for me to understand. > 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:. Noted. I'll keep that in mind for my future patches. > > --- 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. Thank you! > Could reviewers please advise on whether we should backport this into > -stable kernels? > >