Hi Hillf, > On Jun 23, 2019, at 8:16 PM, Hillf Danton <hdanton@xxxxxxxx> wrote: > > > Hello > > On Sun, 23 Jun 2019 13:48:47 +0800 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. The next patch will handle writes, which >> would only happen when the vma with VM_DENYWRITE is unmapped. >> >> An EXPERIMENTAL config, READ_ONLY_THP_FOR_FS, is added to gate this >> feature. >> >> Acked-by: Rik van Riel <riel@xxxxxxxxxxx> >> Signed-off-by: Song Liu <songliubraving@xxxxxx> >> --- >> mm/Kconfig | 11 ++++++ >> mm/filemap.c | 4 +-- >> mm/khugepaged.c | 90 ++++++++++++++++++++++++++++++++++++++++--------- >> mm/rmap.c | 12 ++++--- >> 4 files changed, 96 insertions(+), 21 deletions(-) >> >> diff --git a/mm/Kconfig b/mm/Kconfig >> index f0c76ba47695..0a8fd589406d 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -762,6 +762,17 @@ config GUP_BENCHMARK >> >> See tools/testing/selftests/vm/gup_benchmark.c >> >> +config READ_ONLY_THP_FOR_FS >> + bool "Read-only THP for filesystems (EXPERIMENTAL)" >> + depends on TRANSPARENT_HUGE_PAGECACHE && SHMEM >> + > The ext4 mentioned in the cover letter, along with the subject line of > this patch, suggests the scissoring of SHMEM. We reuse khugepaged code for SHMEM, so the dependency does exist. Thanks, Song
