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    Merge tag 'libnvdimm-for-4.19_dax-memory-failure' of... · 2923b27e
    Linus Torvalds authored
    Merge tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm
    Pull libnvdimm memory-failure update from Dave Jiang:
     "As it stands, memory_failure() gets thoroughly confused by dev_pagemap
      backed mappings. The recovery code has specific enabling for several
      possible page states and needs new enabling to handle poison in dax
      In order to support reliable reverse mapping of user space addresses:
       1/ Add new locking in the memory_failure() rmap path to prevent races
          that would typically be handled by the page lock.
       2/ Since dev_pagemap pages are hidden from the page allocator and the
          "compound page" accounting machinery, add a mechanism to determine
          the size of the mapping that encompasses a given poisoned pfn.
       3/ Given pmem errors can be repaired, change the speculatively
          accessed poison protection, mce_unmap_kpfn(), to be reversible and
          otherwise allow ongoing access from the kernel.
      A side effect of this enabling is that MADV_HWPOISON becomes usable
      for dax mappings, however the primary motivation is to allow the
      system to survive userspace consumption of hardware-poison via dax.
      Specifically the current behavior is:
         mce: Uncorrected hardware memory error in user-access at af34214200
         {1}[Hardware Error]: It has been corrected by h/w and requires no further action
         mce: [Hardware Error]: Machine check events logged
         {1}[Hardware Error]: event severity: corrected
         Memory failure: 0xaf34214: reserved kernel page still referenced by 1 users
         Memory failure: 0xaf34214: recovery action for reserved kernel page: Failed
         mce: Memory error not recovered
      ...and with these changes:
         Injecting memory failure for pfn 0x20cb00 at process virtual address 0x7f763dd00000
         Memory failure: 0x20cb00: Killing dax-pmd:5421 due to hardware memory corruption
         Memory failure: 0x20cb00: recovery action for dax page: Recovered
      Given all the cross dependencies I propose taking this through
      nvdimm.git with acks from Naoya, x86/core, x86/RAS, and of course dax
    * tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm:
      libnvdimm, pmem: Restore page attributes when clearing errors
      x86/memory_failure: Introduce {set, clear}_mce_nospec()
      x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses
      mm, memory_failure: Teach memory_failure() about dev_pagemap pages
      filesystem-dax: Introduce dax_lock_mapping_entry()
      mm, memory_failure: Collect mapping size in collect_procs()
      mm, madvise_inject_error: Let memory_failure() optionally take a page reference
      mm, dev_pagemap: Do not clear ->mapping on final put
      mm, madvise_inject_error: Disable MADV_SOFT_OFFLINE for ZONE_DEVICE pages
      filesystem-dax: Set page->index
      device-dax: Set page->index
      device-dax: Enable page_mapping()
      device-dax: Convert to vmf_insert_mixed and vm_fault_t
memory-failure.c 52.1 KB