On Tue, Apr 08, 2025 at 10:24:40AM -0700, Luis Chamberlain wrote: > On Tue, Apr 8, 2025 at 10:06 AM Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote: > > Fun > > puzzle for the community is figuring out *why* oh why did a large folio > > end up being used on buffer-heads for your use case *without* an LBS > > device (logical block size) being present, as I assume you didn't have > > one, ie say a nvme or virtio block device with logical block size > > > PAGE_SIZE. The area in question would trigger on folio migration *only* > > if you are migrating large buffer-head folios. We only create those > > To be clear, large folios for buffer-heads. > > if > > you have an LBS device and are leveraging the block device cache or a > > filesystem with buffer-heads with LBS (they don't exist yet other than > > the block device cache). My guess is that udev or something tries to read the disk label in response to some uevent (mkfs, mount, unmount, etc), which creates a large folio because min_order > 0, and attaches a buffer head. There's a separate crash report that I'll cc you on. --D
