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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> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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