diff options
| author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2017-02-08 10:27:42 +1100 |
|---|---|---|
| committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2017-02-09 21:53:05 +1100 |
| commit | bda233060a3d5392450fb8b55b4f05462e111a12 (patch) | |
| tree | 9f342b85e5a85ee8cef1fccad39d619f05dfbc43 /mm | |
| parent | 41bb3723f6c61bf38a1ea44e9f11a0f7dc136684 (diff) | |
mm/autonuma: don't use set_pte_at when updating protnone ptes
Architectures like ppc64, use privilege access bit to mark pte non
accessible. This implies that kernel can do a copy_to_user to an address
marked for numa fault. This also implies that there can be a parallel
hardware update for the pte. set_pte_at cannot be used in such scenarios.
Hence switch the pte update to use ptep_get_and_clear and set_pte_at
combination.
Link: http://lkml.kernel.org/r/1486400776-28114-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c index bfad9fe316c1..0c759ba122e1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3400,32 +3400,32 @@ static int do_numa_page(struct vm_fault *vmf) int last_cpupid; int target_nid; bool migrated = false; - pte_t pte = vmf->orig_pte; - bool was_writable = pte_write(pte); + pte_t pte; + bool was_writable = pte_write(vmf->orig_pte); int flags = 0; /* * The "pte" at this point cannot be used safely without * validation through pte_unmap_same(). It's of NUMA type but * the pfn may be screwed if the read is non atomic. - * - * We can safely just do a "set_pte_at()", because the old - * page table entry is not accessible, so there would be no - * concurrent hardware modifications to the PTE. */ vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd); spin_lock(vmf->ptl); - if (unlikely(!pte_same(*vmf->pte, pte))) { + if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { pte_unmap_unlock(vmf->pte, vmf->ptl); goto out; } - /* Make it present again */ + /* + * Make it present again, Depending on how arch implementes non + * accessible ptes, some can allow access by kernel mode. + */ + pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte); pte = pte_modify(pte, vma->vm_page_prot); pte = pte_mkyoung(pte); if (was_writable) pte = pte_mkwrite(pte); - set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); + ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte); update_mmu_cache(vma, vmf->address, vmf->pte); page = vm_normal_page(vma, vmf->address, pte); |