diff --git a/fs/dax.c b/fs/dax.c index c22eaf162f95..2a6889b3585f 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1154,6 +1154,17 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, goto out; } + /* + * It is possible, particularly with mixed reads & writes to private + * mappings, that we have raced with a PMD fault that overlaps with + * the PTE we need to set up. If so just return and the fault will be + * retried. + */ + if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) { + vmf_ret = VM_FAULT_NOPAGE; + goto unlock_entry; + } + /* * Note that we don't bother to use iomap_apply here: DAX required * the file system block size to be equal the page size, which means @@ -1397,6 +1408,18 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, if (IS_ERR(entry)) goto fallback; + /* + * It is possible, particularly with mixed reads & writes to private + * mappings, that we have raced with a PTE fault that overlaps with + * the PMD we need to set up. If so just return and the fault will be + * retried. + */ + if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) && + !pmd_devmap(*vmf->pmd)) { + result = 0; + goto unlock_entry; + } + /* * Note that we don't use iomap_apply here. We aren't doing I/O, only * setting up a mapping, so really we're using iomap_begin() as a way