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charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3344D2000A X-Stat-Signature: c3bh3y7rcdq6eqsbkn96fc3gfyhosrf6 X-Rspam-User: X-HE-Tag: 1765844338-471620 X-HE-Meta: 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 mrPM6AcE 478KS1ICJMq0HLytJIP/CZPaz0uzKPpT5n+wGbRNSkPSyJdI71xKQXpi7vg6Bbmt5KxY7Qo7tf5f9u0i/+1/pxLpOzMgDX3bGHnbMA3Y/cr0KDOJTfztKvjjOzZRe90rR99JXNQTrDQDHvpW38qAKr7oCipKRdJYS2iKZLJ20c7qNYR7PZmjTxKk8SOADIoi2VpuC/3z+cF52EUQJloNbLCWBoXhAcuVfDaIe8J1Qa37HGC3gThlI1QId2b8zJ4YKQ4f0MLHBQ//HPxE65Xng3UqcuHhS0p471gpXcAL3lxp7aU3NYUdGvYOq2WDFHHVzDtQoJzjkWbzLuyZIS8MvOHNXrdihtMNObPA7+TXwdy7+TIrciqkbsOtc7/Eifxs7dTD42H5hUMkKI/2NNTeB23TS3Wll4xBLQ/XOdQ/3kAsmp+OZoZXnSLCmm+NNyB5evtS0Gl/dfclAaaPIFgPucIGKgZpnKLgZmS5Np8SKMfFrTlF946vN8heeKS/iSFyTVGvtrMfuBXVhauJZhNV9TGXxd53denH/dK4BJCX2+B0LPqf+DDFhhWBC2ZuDP0o7JFG+LrunNXlYRF6eBTSZr5mLOvXrU/vNgK4Ugfl6sp19NIUkLXlRq/2+0mrz1PlIAFZT8xTM9goA02k+KDysSy8pS9a0tbasNvf4 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Dec 15, 2025, Vishal Annapurve wrote: > On Mon, Dec 15, 2025 at 7:35=E2=80=AFAM Michael Roth wrote: > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > > index fdaea3422c30..9dafa44838fe 100644 > > --- a/virt/kvm/guest_memfd.c > > +++ b/virt/kvm/guest_memfd.c > > @@ -151,6 +151,15 @@ static struct folio *kvm_gmem_get_folio(struct ino= de *inode, pgoff_t index) > > mapping_gfp_mask(inode->i_mapp= ing), policy); > > mpol_cond_put(policy); > > > > + /* > > + * External interfaces like kvm_gmem_get_pfn() support dealing > > + * with hugepages to a degree, but internally, guest_memfd curr= ently > > + * assumes that all folios are order-0 and handling would need > > + * to be updated for anything otherwise (e.g. page-clearing > > + * operations). > > + */ > > + WARN_ON_ONCE(folio_order(folio)); >=20 > I am not sure if this WARN_ON adds any value. i.e. The current code > can't hit it. The current code _shouldn't_ hit it. > This note concerns future efforts to add hugepage support and could be > omitted altogether from the current implementation. IMO, this is a good use of WARN_ON_ONCE(). It documents guest_memfd's assu= mptions and/or limitations, which is extremely helpful to readers/contributors that= aren't familiar with guest_memfd and/or its history of hugepage support.