linux/drivers/dax
Dave Jiang 0134ed4fb9 device-dax: fix pmd/pte fault fallback handling
Jeff Moyer reports:

    With a device dax alignment of 4KB or 2MB, I get sigbus when running
    the attached fio job file for the current kernel (4.11.0-rc1+).  If
    I specify an alignment of 1GB, it works.

    I turned on debug output, and saw that it was failing in the huge
    fault code.

     dax dax1.0: dax_open
     dax dax1.0: dax_mmap
     dax dax1.0: dax_dev_huge_fault: fio: write (0x7f08f0a00000 -
     dax dax1.0: __dax_dev_pud_fault: phys_to_pgoff(0xffffffffcf60
     dax dax1.0: dax_release

    fio config for reproduce:
    [global]
    ioengine=dev-dax
    direct=0
    filename=/dev/dax0.0
    bs=2m

    [write]
    rw=write

    [read]
    stonewall
    rw=read

The driver fails to fallback when taking a fault that is larger than
the device alignment, or handling a larger fault when a smaller
mapping is already established. While we could support larger
mappings for a device with a smaller alignment, that change is
too large for the immediate fix. The simplest change is to force
fallback until the fault size matches the alignment.

Fixes: dee4107924 ("/dev/dax, core: file operations and dax-mmap")
Cc: <stable@vger.kernel.org>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-03-10 18:15:04 -08:00
..
dax.c device-dax: fix pmd/pte fault fallback handling 2017-03-10 18:15:04 -08:00
dax.h dax: convert devm_create_dax_dev to PTR_ERR 2016-10-07 16:45:59 -07:00
Kconfig nvdimm: make CONFIG_NVDIMM_DAX 'bool' 2016-10-27 16:16:21 -07:00
Makefile
pmem.c Merge branch 'for-4.10/libnvdimm' into libnvdimm-for-next 2016-12-17 15:08:10 -08:00