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Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , Vlastimil Babka , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev Content-Type: text/plain; charset="us-ascii" On Tue, Jun 23, 2026, Binbin Wu wrote: > On 6/19/2026 8:31 AM, Ackerley Tng via B4 Relay wrote: > > @@ -606,12 +608,20 @@ static bool kvm_gmem_is_safe_for_conversion(struct inode *inode, pgoff_t start, > > next = start; > > while (safe && filemap_get_folios(mapping, &next, last, &fbatch)) { > > > > - for (i = 0; i < folio_batch_count(&fbatch); ++i) { > > + for (i = 0; i < folio_batch_count(&fbatch);) { > > struct folio *folio = fbatch.folios[i]; > > > > - if (folio_ref_count(folio) != > > - folio_nr_pages(folio) + filemap_get_folios_refcount) { > > - safe = false; > > + safe = (folio_ref_count(folio) == > > + folio_nr_pages(folio) + > > + filemap_get_folios_refcount); > > + > > + if (safe) { > > + ++i; > > + } else if (folio_may_be_lru_cached(folio) && > > + !lru_drained) { > > + lru_add_drain_all(); > > It seems unprivileged userspace is able to trigger lru_add_drain_all() repeatedly > by invoking KVM_SET_MEMORY_ATTRIBUTES2 in a loop, which could lead to DoS risk? FIW, if there's a risk, then AFAICT fadvise() and memfd's F_ADD_SEALS already have the same risk.