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Sat, 31 Oct 2026 04:33:09 +0000 X-Mizu-Trace-ID: ea78379c5260a3be X-Migadu-Flow: FLOW_OUT Date: Sat, 31 Oct 2026 04:33:06 +0000 From: Jose Fernandez To: "David Hildenbrand (Arm)" Cc: "Matthew Wilcox (Oracle)" , Jan Kara , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Krystian Kaniewski Subject: Re: [PATCH] mm/filemap: stop fault-around when the walk steps back Message-ID: <20261031-jf-mm-filemap-reply-r2-7d4c1e9ab350@linux.dev> References: <20261028-jf-mm-filemap-map-pages-lower-bound-v1-1-0bf126e876d4@linux.dev> <0a1ad7d2-ff0e-4248-8f03-2a64a9134aae@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0a1ad7d2-ff0e-4248-8f03-2a64a9134aae@kernel.org> X-Stat-Signature: dj7hind861q9jybjfjyjeby4gkmdko5z X-Rspamd-Queue-Id: D803DC0002 X-Rspam-User: X-Rspamd-Server: rspam12 X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793421199-597893 X-HE-Meta: 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 pBX63fGY zM1dmRxJXfYQy9EpoUfZAbGEzqsikb9Ay8cx07rLlDbPB0P9LbV97uET7eSxz7KlAVu8A52xawpKVmTPZhkSOophIoF3XdGciPXxwLAwpnfeBV6XJbK/lWt8Yu3vlRsyeds66seJTOaM0ToLbTLOlU9Bm0k+voWPfIKwGcLWgchnTZd3lFYNJacIJmV79cZkfZMj+lhhhehJpRkCCFRSkPJDBYMpZpjD2oc2vXVCH7wrpnK1k/9Etr1yMRCd3eI4b01TpgHmLCrO123SoiyBU1NF3Ah+eK1s1B0n1vG+WnN4VPXdr8XdHxuEEMJxaJPUm5jmqPz+F3SbLQnWuCJ9B039FommYNWX82ntQaNoigN3VwYzTdqtf5wmJ3g== 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 Thu, Oct 29, 2026 David Hildenbrand (Arm) wrote: > Only read or also write? I assume only read. Both. KASAN only reports the read, but once vmf->pte has stepped outside the page table the loop will also call set_pte_range() on that slot if it reads as pte_none(), so a stray write is possible too. I'll call that out in the v2 changelog. > Sounds like we want a Fixes: tag and Cc: stable? :) Yes, v2 will carry both. - Jose