Changes since v3 [1]: * Introduce dax_lock_page(), using the radix exceptional entry lock, for pinning down page->mapping while memory_failure() interrogates the page. (Jan) * Collect acks and reviews from Tony and Jan. [1]: https://lists.01.org/pipermail/linux-nvdimm/2018-June/016153.html --- 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 mappings. 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 <reboot> ...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 --- Dan Williams (12): device-dax: Convert to vmf_insert_mixed and vm_fault_t device-dax: Cleanup vm_fault de-reference chains device-dax: Enable page_mapping() device-dax: Set page->index filesystem-dax: Set page->index mm, madvise_inject_error: Let memory_failure() optionally take a page reference x86/mm/pat: Prepare {reserve,free}_memtype() for "decoy" addresses x86/memory_failure: Introduce {set,clear}_mce_nospec() mm, memory_failure: Pass page size to kill_proc() filesystem-dax: Introduce dax_lock_page() mm, memory_failure: Teach memory_failure() about dev_pagemap pages libnvdimm, pmem: Restore page attributes when clearing errors arch/x86/include/asm/set_memory.h | 42 +++++++++ arch/x86/kernel/cpu/mcheck/mce-internal.h | 15 --- arch/x86/kernel/cpu/mcheck/mce.c | 38 +------- arch/x86/mm/pat.c | 16 +++ drivers/dax/device.c | 97 ++++++++++++-------- drivers/nvdimm/pmem.c | 26 +++++ drivers/nvdimm/pmem.h | 13 +++ fs/dax.c | 92 ++++++++++++++++++- include/linux/dax.h | 15 +++ include/linux/huge_mm.h | 5 + include/linux/mm.h | 1 include/linux/set_memory.h | 14 +++ mm/huge_memory.c | 4 - mm/madvise.c | 18 +++- mm/memory-failure.c | 143 +++++++++++++++++++++++++++-- 15 files changed, 434 insertions(+), 105 deletions(-)
