On Thu, 30 Apr 2026 10:37:52 -0400 Zi Yan <[email protected]> wrote: > + * MADV_COLLAPSE ignores shmem huge config, so do not check shmem > > + * > > + * TODO: once shmem always calls mapping_set_large_folios() on its > > + * mapping, the shmem check can be removed. > > + */ > > + VM_WARN_ON_ONCE(!is_shmem && !mapping_pmd_folio_support(mapping)); > > sashiko asked: > Is it possible for userspace to intentionally trigger this warning via > madvise(MADV_COLLAPSE) on an unsupported read-only file? Although in > a later commit, modified file_thp_enabled() will prevent this. > > Answer: > It is possible when CONFIG_READ_ONLY_THP_FOR_FS is enabled, but it is > unlikely a kernel will be shipped at this exact commit.
Yeah, let's not worry about minor bisection holes.
