• Chuck Lever's avatar
    xprtrdma: Fix list corruption / DMAR errors during MR recovery · 054f1557
    Chuck Lever authored
    The ro_release_mr methods check whether mr->mr_list is empty.
    Therefore, be sure to always use list_del_init when removing an MR
    linked into a list using that field. Otherwise, when recovering from
    transport failures or device removal, list corruption can result, or
    MRs can get mapped or unmapped an odd number of times, resulting in
    IOMMU-related failures.
    
    In general this fix is appropriate back to v4.8. However, code
    changes since then make it impossible to apply this patch directly
    to stable kernels. The fix would have to be applied by hand or
    reworked for kernels earlier than v4.16.
    
    Backport guidance -- there are several cases:
    - When creating an MR, initialize mr_list so that using list_empty
      on an as-yet-unused MR is safe.
    - When an MR is being handled by the remote invalidation path,
      ensure that mr_list is reinitialized when it is removed from
      rl_registered.
    - When an MR is being handled by rpcrdma_destroy_mrs, it is removed
      from mr_all, but it may still be on an rl_registered list. In
      that case, the MR needs to be removed from that list before being
      released.
    - Other cases are covered by using list_del_init in rpcrdma_mr_pop.
    
    Fixes: 9d6b0409 ('xprtrdma: Place registered MWs on a ... ')
    Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
    Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
    054f1557
frwr_ops.c 15.7 KB