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Fri, 06 Nov 2026 01:56:15 -0800 (PST) Received: from [192.168.1.22] ([83.231.69.9]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-492d7dbb0d4sm2752385f8f.50.2026.11.06.01.56.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Nov 2026 01:56:15 -0800 (PST) Message-ID: Date: Fri, 6 Nov 2026 10:56:11 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/5] mm/mmu_gather: flush pending references early before the folio limit To: "David Hildenbrand (Arm)" , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Johannes Weiner , Song Liu , Rik van Riel , Hugh Dickins , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Jason Gunthorpe , Kevin Tian , "Joerg Roedel (AMD)" , Robin Murphy , Steve Sistare , John Hubbard Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, iommu@lists.linux.dev, Chris Mason , stable@vger.kernel.org References: <20261105-refcount_overflow_stable-v1-0-70b9c655da3e@kernel.org> <20261105-refcount_overflow_stable-v1-3-70b9c655da3e@kernel.org> Content-Language: en-US From: "Jose A. Perez de Azpillaga" In-Reply-To: <20261105-refcount_overflow_stable-v1-3-70b9c655da3e@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 3emzc5mqnd8dauh49bssq38z4yr1p74k X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 394E840005 X-Spam-Status: No, score=-9.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793958977-867469 X-HE-Meta: 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 moaeHl8h 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/5/26 2:10 PM, David Hildenbrand (Arm) wrote: > When a task zaps mappings (e.g., MADV_DONTNEED), it can drop the PT lock > and defer dropping the folio references. In the meantime, page faults > can refault pagecache folios, creating more references for the same > folios. > > Let's just request a flush after enqueueing a pagecache folio whose > refcount reached a certain threshold. Start flushing well before new > references are refused, regardless of the caller's privileges. > > This is a temporary measure until we have something better. > > Reported-by: Chris Mason > Fixes: 10ebac4f95e7 ("mm/memory: optimize unmap/zap with PTE-mapped THP") > Cc: stable@vger.kernel.org > Signed-off-by: David Hildenbrand (Arm) LGTM: Reviewed-by: Jose A. Perez de Azpillaga -- cheers, jose a. p-a