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| author | Dan Williams <dan.j.williams@intel.com> | 2017-10-23 16:20:00 +0200 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2018-01-20 01:50:53 +0100 |
| commit | 785a3fab4adbf91b2189c928a59ae219c54ba95e (patch) | |
| tree | 7a3f3342c336eb99cbc7ddbe09741af78d7e99b2 /mm | |
| parent | mm: Fix devm_memremap_pages() collision handling (diff) | |
| download | linux-785a3fab4adbf91b2189c928a59ae219c54ba95e.tar.xz linux-785a3fab4adbf91b2189c928a59ae219c54ba95e.zip | |
mm, dax: introduce pfn_t_special()
In support of removing the VM_MIXEDMAP indication from DAX VMAs,
introduce pfn_t_special() for drivers to indicate that _PAGE_SPECIAL
should be used for DAX ptes. This also helps identify drivers like
dccssblk that only want to use DAX in a read-only fashion without
get_user_pages() support.
Ideally we could delete axonram and dcssblk DAX support, but if we need
to keep it better make it explicit that axonram and dcssblk only support
a sub-set of DAX due to missing _PAGE_DEVMAP support.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c index ca5674cbaff2..46b6c33b7f04 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1897,12 +1897,26 @@ int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, } EXPORT_SYMBOL(vm_insert_pfn_prot); +static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) +{ + /* these checks mirror the abort conditions in vm_normal_page */ + if (vma->vm_flags & VM_MIXEDMAP) + return true; + if (pfn_t_devmap(pfn)) + return true; + if (pfn_t_special(pfn)) + return true; + if (is_zero_pfn(pfn_t_to_pfn(pfn))) + return true; + return false; +} + static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, pfn_t pfn, bool mkwrite) { pgprot_t pgprot = vma->vm_page_prot; - BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); + BUG_ON(!vm_mixed_ok(vma, pfn)); if (addr < vma->vm_start || addr >= vma->vm_end) return -EFAULT; |