Re: [PATCH v1 00/11] mm: migrate: support poison recover from migrate folio

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi, since rfcv2, there is no more changes, kindly ping, any comments, thanks all.

On 2024/3/21 11:27, Kefeng Wang wrote:
The folio migration is widely used in kernel, memory compaction, memory
hotplug, soft offline page, numa balance, memory demote/promotion, etc,
but once access a poisoned source folio when migrating, the kerenl will
panic.

There is a mechanism in the kernel to recover from uncorrectable memory
errors, ARCH_HAS_COPY_MC(Machine Check Safe Memory Copy), which is already
used in NVDIMM or core-mm paths(eg, CoW, khugepaged, coredump, ksm copy),
see copy_mc_to_{user,kernel}, copy_mc_{user_}highpage callers.

This series of patches provide the recovery mechanism from folio copy for
the widely used folio migration. Please note, because folio migration is
no guarantee of success, so we could chose to make folio migration tolerant
of memory failures, adding folio_mc_copy() which is a #MC versions of
folio_copy(), once accessing a poisoned source folio, we could return error
and make the folio migration fail, and this could avoid the similar panic
shown below.

   CPU: 1 PID: 88343 Comm: test_softofflin Kdump: loaded Not tainted 6.6.0
   pc : copy_page+0x10/0xc0
   lr : copy_highpage+0x38/0x50
   ...
   Call trace:
    copy_page+0x10/0xc0
    folio_copy+0x78/0x90
    migrate_folio_extra+0x54/0xa0
    move_to_new_folio+0xd8/0x1f0
    migrate_folio_move+0xb8/0x300
    migrate_pages_batch+0x528/0x788
    migrate_pages_sync+0x8c/0x258
    migrate_pages+0x440/0x528
    soft_offline_in_use_page+0x2ec/0x3c0
    soft_offline_page+0x238/0x310
    soft_offline_page_store+0x6c/0xc0
    dev_attr_store+0x20/0x40
    sysfs_kf_write+0x4c/0x68
    kernfs_fop_write_iter+0x130/0x1c8
    new_sync_write+0xa4/0x138
    vfs_write+0x238/0x2d8
    ksys_write+0x74/0x110

v1:
- no change, resend and rebased on 6.9-rc1

rfcv2:
- Separate __migrate_device_pages() cleanup from patch "remove
   migrate_folio_extra()", suggested by Matthew
- Split folio_migrate_mapping(), move refcount check/freeze out
   of folio_migrate_mapping(), suggested by Matthew
- add RB

Kefeng Wang (11):
   mm: migrate: simplify __buffer_migrate_folio()
   mm: migrate_device: use more folio in __migrate_device_pages()
   mm: migrate_device: unify migrate folio for MIGRATE_SYNC_NO_COPY
   mm: migrate: remove migrate_folio_extra()
   mm: remove MIGRATE_SYNC_NO_COPY mode
   mm: migrate: split folio_migrate_mapping()
   mm: add folio_mc_copy()
   mm: migrate: support poisoned recover from migrate folio
   fs: hugetlbfs: support poison recover from hugetlbfs_migrate_folio()
   mm: migrate: remove folio_migrate_copy()
   fs: aio: add explicit check for large folio in aio_migrate_folio()

  fs/aio.c                     |  15 ++--
  fs/hugetlbfs/inode.c         |   5 +-
  include/linux/migrate.h      |   3 -
  include/linux/migrate_mode.h |   5 --
  include/linux/mm.h           |   1 +
  mm/balloon_compaction.c      |   8 --
  mm/migrate.c                 | 157 +++++++++++++++++------------------
  mm/migrate_device.c          |  28 +++----
  mm/util.c                    |  20 +++++
  mm/zsmalloc.c                |   8 --
  10 files changed, 115 insertions(+), 135 deletions(-)





[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux