On Mon, May 08, 2023 at 10:22:33AM +0800, 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> Looks good to me, thank you. Reviewed-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
