On Thu, Aug 01, 2019 at 11:42:43AM -0700, Song Liu wrote: > This patch is (hopefully) the first step to enable THP for non-shmem > filesystems. > > This patch enables an application to put part of its text sections to THP > via madvise, for example: > > madvise((void *)0x600000, 0x200000, MADV_HUGEPAGE); > > We tried to reuse the logic for THP on tmpfs. > > Currently, write is not supported for non-shmem THP. khugepaged will only > process vma with VM_DENYWRITE. sys_mmap() ignores VM_DENYWRITE requests > (see ksys_mmap_pgoff). The only way to create vma with VM_DENYWRITE is > execve(). This requirement limits non-shmem THP to text sections. > > The next patch will handle writes, which would only happen when the all > the vmas with VM_DENYWRITE are unmapped. > > An EXPERIMENTAL config, READ_ONLY_THP_FOR_FS, is added to gate this > feature. > > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Acked-by: Rik van Riel <riel@xxxxxxxxxxx> > Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Signed-off-by: Song Liu <songliubraving@xxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
