[0/3] Enhance soft hwpoison handling and injection

Message

Jane Chu May 1, 2024, 11:24 p.m. UTC

This series aim at the following enhancement -
1. Let one hwpoison injector, that is, madvise(MADV_HWPOISON) to behave
   more like as if a real UE occurred. Because the other two injectors
   such as hwpoison-inject and the 'einj' on x86 can't, and it seems to
   me we need a better simulation to real UE scenario.
2. For years, if the kernel is unable to unmap a hwpoisoned page, it send
   a SIGKILL instead of SIGBUS to prevent user process from potentially
   accessing the page again. But in doing so, the user process also lose
   important information: vaddr, for recovery.  Fortunately, the kernel
   already has code to kill process re-accessing a hwpoisoned page, so
   remove the '!unmap_success' check.
3. Right now, if a thp page under GUP longterm pin is hwpoisoned, and
   kernel cannot split the thp page, memory-failure simply ignores
   the UE and returns.  That's not ideal, it could deliver a SIGBUS with
   useful information for userspace recovery.


Jane Chu (3):
  mm/memory-failure: try to send SIGBUS even if unmap failed
  mm/madvise: Add MF_ACTION_REQUIRED to madvise(MADV_HWPOISON)
  mm/memory-failure: send SIGBUS in the event of thp split fail

 mm/madvise.c        |  2 +-
 mm/memory-failure.c | 49 ++++++++++++++++++++++++++++++++++++---------
 2 files changed, 41 insertions(+), 10 deletions(-)