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Sun, 18 Oct 2026 07:59:36 +0000 X-Mizu-Trace-ID: 77426602997a8cfb X-Migadu-Flow: FLOW_OUT From: Lance Yang To: david@kernel.org Cc: akpm@linux-foundation.org, liam@infradead.org, ljs@kernel.org, vbabka@kernel.org, jannh@google.com, pfalcato@suse.de, muchun.song@linux.dev, osalvador@suse.de, linmiaohe@huawei.com, nao.horiguchi@gmail.com, agl@us.ibm.com, mel@csn.ul.ie, riel@surriel.com, peterx@redhat.com, kas@kernel.org, rppt@kernel.org, josef@toxicpanda.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 07/10] mm/hugetlb: tolerate uffd bits set without uffd for PROT_NONE PTEs Date: Sun, 18 Oct 2026 15:59:27 +0800 Message-ID: <20261018075927.2979-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261015-urgent_fixes-v1-7-42796911043b@kernel.org> References: <20261015-urgent_fixes-v1-7-42796911043b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 534D420002 X-Stat-Signature: 7u3g8cupb4i4rk8ecf5jebe4zyyoobyj X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1792310378-929258 X-HE-Meta: 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 AjbZAuzw UR9VUs0FjzfgXYXyuOkKxYDj+CFWOPE+QS3UpqtHtKmEIzDOB/LRxqL5ZIunngtN07U81Qc2JUPj4QnWNTggtORB8e4Y3/qr3S8Ze4fXO1aWXm8J84sZ6CXAEM+/d9ASqI6mCM7EJnmoEPUpatEuDJLzwTYFPt58HG7+mnGzQjXgXd1Fli+1D5RzacfKYuUY8HmJjDlxxWhvjMBdlxkt7uXyZz/Jt+aoYZBNBNid1TZFmeEENDoYxnrg934I7X4fzV19CKvjrEWLCpwJBkup3zLWIlxLJNnV+YgIRQcbFe66yuoGMVwwtSuSui/C7mD6zPiEXnqZlVuMByj0S1SvTbqZWddF5bTWFN3/xnxDIzFo+B7b4eAAy9G4l+XPA9D8l4u03 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Oct 15, 2026 at 06:07:13PM +0200, David Hildenbrand (Arm) wrote: >The whole uffd handling when a VMA is unregistered from UFFD is shaky: >there are still some scenarios where we might have stale uffd PTE bits >in VMAs no longer registered for UFFD, which confuses other code. > >Let's just tolerate that for now and simply clear the PTE bit. Add a >TODO to really clean up any uffd leftovers when unregistering a VMA from >userfaultfd. > >The handling is now more similar to what we have in handle_pte_fault(). > >Fixes: 2d427bb01639 ("mm/userfaultfd: add RWP fault delivery and expose UFFDIO_REGISTER_MODE_RWP") >Cc: stable@vger.kernel.org >Signed-off-by: David Hildenbrand (Arm) >--- Reviewed-by: Lance Yang