[PATCH v4 0/3] mm/hwpoison: fix unpoison_memory()

[Naoya Horiguchi]

Hi,

I updated the unpoison patchset based on feedbacks for v3.

I fixed a typo in patch description and closed raced in
unpoison_taken_off_page() reported by Yang Shi.  As for the build
failure reported from build bot, I commented about disabling
X86_SUPPORTS_MEMORY_FAILURE for i386 at first, but I'm not 100% sure
that someone could use the subsystem for 32 bit system, so I shift to
the easier way (setting MAGIC_HWPOISON to 32-bit integer value).

----- (cover letter copied from v2) -----
Main purpose of this series is to sync unpoison code to recent changes
around how hwpoison code takes page refcount.  Unpoison should work or
simply fail (without crash) if impossible.

The recent works of keeping hwpoison pages in shmem pagecache introduce
a new state of hwpoisoned pages, but unpoison for such pages is not
supported yet with this series.

It seems that soft-offline and unpoison can be used as general purpose
page offline/online mechanism (not in the context of memory error). I
think that we need some additional works to realize it because currently
soft-offline and unpoison are assumed not to happen so frequently
(print out too many messages for aggressive usecases). But anyway this
could be another interesting next topic.

v1: https://lore.kernel.org/linux-mm/20210614021212.223326-1-nao.horiguchi@xxxxxxxxx/
v2: https://lore.kernel.org/linux-mm/20211025230503.2650970-1-naoya.horiguchi@xxxxxxxxx/
v3: https://lore.kernel.org/linux-mm/20211105055058.3152564-1-naoya.horiguchi@xxxxxxxxx/

Thanks,
Naoya Horiguchi
---
Summary:

Naoya Horiguchi (3):
      mm/hwpoison: mf_mutex for soft offline and unpoison
      mm/hwpoison: remove MF_MSG_BUDDY_2ND and MF_MSG_POISONED_HUGE
      mm/hwpoison: fix unpoison_memory()

 include/linux/mm.h         |   3 +-
 include/linux/page-flags.h |   4 ++
 include/ras/ras_event.h    |   2 -
 mm/memory-failure.c        | 171 ++++++++++++++++++++++++++++-----------------
 mm/page_alloc.c            |  27 +++++++
 5 files changed, 139 insertions(+), 68 deletions(-)