[00/10] huge_memory,khugepaged tmpfs split/collapse fixes

Message

Hugh Dickins Nov. 26, 2018, 11:13 p.m. UTC

Hi Andrew,

Here's a set of 10 patches, mostly fixing some crashes and lockups
which can happen when khugepaged collapses tmpfs pages to huge:
by-products of ongoing work to extend upstream's huge tmpfs to
match what we need in Google (but no enhancements included here).

Against v4.20-rc2 == v4.20-rc4: sorry, I haven't looked yet to see
what clashes there might be with mmotm, because I believe that although
these are all (except 10/10) to long-standing bugs, they still deserve
to get into v4.20 and -stable.  See what you think.

Most of the testing has been on the whole series, and on a slightly
earlier kernel: the move to XArray means that almost none of these
patches will apply cleanly to v4.19 or earlier, but I do have the
equivalents lined up ready.

 mm/huge_memory.c |   43 ++++++++-----
 mm/khugepaged.c  |  140 ++++++++++++++++++++++++++-------------------
 mm/rmap.c        |   13 ----
 mm/shmem.c       |    6 +
 4 files changed, 114 insertions(+), 88 deletions(-)

 1/10 mm/huge_memory: rename freeze_page() to unmap_page()
 2/10 mm/huge_memory: splitting set mapping+index before unfreeze
 3/10 mm/huge_memory: fix lockdep complaint on 32-bit i_size_read()
 4/10 mm/khugepaged: collapse_shmem() stop if punched or truncated
 5/10 mm/khugepaged: fix crashes due to misaccounted holes
 6/10 mm/khugepaged: collapse_shmem() remember to clear holes
 7/10 mm/khugepaged: minor reorderings in collapse_shmem()
 8/10 mm/khugepaged: collapse_shmem() without freezing new_page
 9/10 mm/khugepaged: collapse_shmem() do not crash on Compound
10/10 mm/khugepaged: fix the xas_create_range() error path

Thanks,
Hugh