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Tue, 22 Sep 2026 05:41:20 -0700 (PDT) From: Donggeun Yoo To: david@kernel.org Cc: akpm@linux-foundation.org, rppt@kernel.org, peterx@redhat.com, surenb@google.com, aarcange@redhat.com, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, mhocko@suse.com, shuah@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, donggeunyoo.kernel@gmail.com Subject: Re: [PATCH v1 1/2] userfaultfd: clear the inherited uffd bit in move_swap_pte() Date: Tue, 22 Sep 2026 21:41:13 +0900 Message-ID: <20260922124113.1675993-1-donggeunyoo.kernel@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <49208ed6-6c20-49a9-9c0d-0e1cffe1898f@kernel.org> References: <20260919004630.1159895-2-donggeunyoo.kernel@gmail.com> <49208ed6-6c20-49a9-9c0d-0e1cffe1898f@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 5pmqqfpmewknynmd1tj9o5snqjqd5ynj X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A06F0140007 X-HE-Tag: 1790080882-329514 X-HE-Meta: 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 8s08XBxq IFCN+3lvjMC/atken7gO98uzPsnis5ZiQnJr9i/TJgD3ttVB9xp46pA1deZcF9S+gQmJISr0cqDa69c5QkOhUY4HlC1TAest5CDFgJlzlrjW3QzbDpMBUMSljG89pdtjuYPQHeZdIqmG5TfF+E3UCbJfzUEojCnwplVB/OmbLkEtPm8+7pzaDx8XZlJfBAGl1GnC97AbS/Lb+65rxzWKy07Ka620k5nmO3ECTg4WqqRMjZXBtCOlhfSeJVvIGtuZNFevKOocDD98xqL1r7xsHl4y2IZSCOhAOqYsR9rJ1MuTleZh4REaaumBcQfUOkIYItPlNK9NKfPyZhWE9JQLRoM6o0zu4xR+nX7MxF2PeRKHmt1Co+WsgLcY9KJfi9iNVYMY2EJ85Jw0dsWpgNS4VO5Qz3myMeb2pAZDzqd1xUDO0lPJ9hWa5Nl92ZuOkZOSjB3X9gegZA9zyQBZlpjv/gH+P+jfl5iKC6BOjdLovPEWEzahUuSwdThun0XXwN8sJ3o1mIRkN8VLR+puHp0oEdthhLVHvAtgULP3v9vhJvvUZpHin+Oq668pVdQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Thank you for the review. My guess is that wp protection always leaves the destination PTE non-none, and the move path has 1566 if (!pte_none(orig_dst_pte)) { 1567 ret = -EEXIST; 1568 goto out; 1569 } The move fails when the destination PTE is not none. So there's nothing to preserve for wp in the first place.