[PATCH 0/3] Enhance soft hwpoison handling and injection

Jane Chu
2024-05-02T00:12:23Z

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(-)

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2.39.3