From: Huaisheng Ye <[email protected]>

pmem_direct_access() needs to check the validity of pointer pfn for NULL
assignment. If pfn equals to NULL, it doesn't need to calculate the
value. This is in support of asynchronous memmap init and avoid page
lookups when possible.

Signed-off-by: Huaisheng Ye <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
---
 drivers/nvdimm/pmem.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index e8ac6f244d2b..c430536320a5 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -228,7 +228,8 @@ __weak long __pmem_direct_access(struct pmem_device *pmem, 
pgoff_t pgoff,
                                        PFN_PHYS(nr_pages))))
                return -EIO;
        *kaddr = pmem->virt_addr + offset;
-       *pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+       if (pfn)
+               *pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
        /*
         * If badblocks are present, limit known good range to the

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