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    SubjectRe: [RFC PATCH v2 00/16] Hwpoison rework {hard,soft}-offline
    Date
    Hi Dmitry,

    On Thu, Jun 11, 2020 at 07:43:19PM +0300, Dmitry Yakunin wrote:
    > Hello!
    >
    > We are faced with similar problems with hwpoisoned pages
    > on one of our production clusters after kernel update to stable 4.19.
    > Application that does a lot of memory allocations sometimes caught SIGBUS signal
    > with message in dmesg about hardware memory corruption fault.
    > In kernel and mce logs we saw messages about soft offlining pages with
    > correctable errors. Those events always had happened before application
    > was killed. This is not the behavior we expect. We want our application to
    > continue working on a smaller set of available pages in the system.
    >
    > This issue is difficult to reproduce, but we suppose that the reason for such
    > behavior is that compaction does not check for page poisonness while processing
    > free pages, so as a result valid userspace data gets migrated to bad pages.
    > We wrote the simple test:
    > - soft offline first 4 pages in every 64 continuous pages in ZONE_NORMAL
    > through writing pfn to /sys/devices/system/memory/soft_offline_page
    > - force compaction by echo 1 >> /proc/sys/vm/compact_memory
    > Without this patch series after these steps bash became unusable
    > and every attempt to run any command leads to SIGBUS with message about
    > hardware memory corruption fault. And after applying this series to our kernel
    > tree we cannot reproduce such SIGBUSes by our test. On upstream kernel 5.7
    > this behavior is still reproducible.
    >
    > So, we want to know, why this patchset wasn't merged to the upstream?
    > Is there any problems in such rework for {soft,hard}-offline handling?

    No technical reason, it's just because I didn't have enough power to push
    this to be merged. Really sorry about that.

    > BTW, this patchset should be updated with upstream changes in mm.

    I'm working this now and still need more testing to confirm, but I hope
    I'll update and post this for 5.9.

    Thanks,
    Naoya Horiguchi
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