Hi x86/mm maintainers, could you pick this up as it has be reviewed by Naoya and Tony, many thanks. On 2023/5/8 10:22, Kefeng Wang wrote:
Both EX_TYPE_FAULT_MCE_SAFE and EX_TYPE_DEFAULT_MCE_SAFE exception fixup types are used to identify fixups which allow in kernel #MC recovery, that is the Machine Check Safe Copy. For now, the MCE_IN_KERNEL_COPYIN flag is only set for EX_TYPE_COPY and EX_TYPE_UACCESS when copy from user, and corrupted page is isolated in this case, for MC-safe copy, memory_failure() is not always called, some places, like __wp_page_copy_user, copy_subpage, copy_user_gigantic_page and ksm_might_need_to_copy manually call memory_failure_queue() to cope with such unhandled error pages, recently coredump hwposion recovery support[1] is asked to do the same thing, and there are some other already existed MC-safe copy scenarios, eg, nvdimm, dm-writecache, dax, which has similar issue. The best way to fix them is set MCE_IN_KERNEL_COPYIN to MCE_SAFE exception, then kill_me_never() will be queued to call memory_failure() in do_machine_check() to isolate corrupted page, which avoid calling memory_failure_queue() after every MC-safe copy return. [1] https://lkml.kernel.org/r/20230417045323.11054-1-wangkefeng.wang@xxxxxxxxxx Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
