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SubjectRe: [PATCH v6 00/13] mm: Teach memory_failure() about ZONE_DEVICE pages
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Ingo,
Is it possible to ack the x86 bits in this patch series? I'm hoping to
get this pulled through the libnvdimm tree for 4.19. Thanks!

On 07/13/2018 09:49 PM, Dan Williams wrote:
> Changes since v5 [1]:
> * Move put_page() before memory_failure() in madvise_inject_error()
> (Naoya)
> * The previous change uncovered a latent bug / broken assumption in
> __put_devmap_managed_page(). We need to preserve page->mapping for
> dax pages when they go idle.
> * Rename mapping_size() to dev_pagemap_mapping_size() (Naoya)
> * Catch and fail attempts to soft-offline dax pages (Naoya)
> * Collect Naoya's ack on "mm, memory_failure: Collect mapping size in
> collect_procs()"
>
> [1]: https://lists.01.org/pipermail/linux-nvdimm/2018-July/016682.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
>
> Given all the cross dependencies I propose taking this through
> nvdimm.git with acks from Naoya, x86/core, x86/RAS, and of course dax
> folks.
>
> ---
>
> Dan Williams (13):
> device-dax: Convert to vmf_insert_mixed and vm_fault_t
> device-dax: Enable page_mapping()
> device-dax: Set page->index
> filesystem-dax: Set page->index
> mm, madvise_inject_error: Disable MADV_SOFT_OFFLINE for ZONE_DEVICE pages
> mm, dev_pagemap: Do not clear ->mapping on final put
> mm, madvise_inject_error: Let memory_failure() optionally take a page reference
> mm, memory_failure: Collect mapping size in collect_procs()
> filesystem-dax: Introduce dax_lock_mapping_entry()
> mm, memory_failure: Teach memory_failure() about dev_pagemap pages
> x86/mm/pat: Prepare {reserve,free}_memtype() for "decoy" addresses
> x86/memory_failure: Introduce {set,clear}_mce_nospec()
> 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 | 75 +++++++---
> drivers/nvdimm/pmem.c | 26 ++++
> drivers/nvdimm/pmem.h | 13 ++
> fs/dax.c | 125 ++++++++++++++++-
> include/linux/dax.h | 13 ++
> include/linux/huge_mm.h | 5 -
> include/linux/mm.h | 1
> include/linux/set_memory.h | 14 ++
> kernel/memremap.c | 1
> mm/hmm.c | 2
> mm/huge_memory.c | 4 -
> mm/madvise.c | 16 ++
> mm/memory-failure.c | 210 +++++++++++++++++++++++------
> 17 files changed, 481 insertions(+), 135 deletions(-)
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
>

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