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[95.203.22.87]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-3a9c3cd2f24sm37276021fa.28.2026.10.13.09.48.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Oct 2026 09:48:08 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 13 Oct 2026 18:48:06 +0200 To: Suren Baghdasaryan , Hao Ge Cc: Hao Ge , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter , Uladzislau Rezki , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org Subject: Re: [RFC PATCH 4/4] mm/percpu: stop unmapping the CPU that failed to map Message-ID: References: <20261009063619.112313-1-hao.ge@linux.dev> <20261009063619.112313-5-hao.ge@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: BEC0980007 X-Rspam-User: X-Stat-Signature: ahhj83mkiehbk3xye1w4i7iziooi4mdd X-HE-Tag: 1791910090-311257 X-HE-Meta: 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 9brBnnaT 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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, Oct 13, 2026 at 03:46:43PM +0400, Suren Baghdasaryan wrote: > On Fri, Oct 9, 2026 at 10:36 AM Hao Ge wrote: > > > > __pcpu_map_pages() clears the PTEs it installed when it fails, so > > pcpu_map_pages() only has to tear down the CPUs it mapped before > > the failing one. > > > > Signed-off-by: Hao Ge > > Reviewed-by: Suren Baghdasaryan > > > > --- > > mm/percpu-vm.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c > > index 509d8901835c..59d3a336a6bd 100644 > > --- a/mm/percpu-vm.c > > +++ b/mm/percpu-vm.c > > @@ -252,10 +252,11 @@ static int pcpu_map_pages(struct pcpu_chunk *chunk, struct page **pages, > > return 0; > > err: > > for_each_possible_cpu(tcpu) { > > - __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start), > > - page_end - page_start); > > + /* The failing CPU's partial mapping undoes itself */ > > if (tcpu == cpu) > > break; > > + __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start), > > + page_end - page_start); > > } > > pcpu_post_unmap_tlb_flush(chunk, page_start, page_end); > > return err; > > -- > > 2.25.1 > > Reviewed-by: Uladzislau Rezki (Sony) -- Uladzislau Rezki