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author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2017-02-24 14:59:13 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-24 17:46:56 -0800 |
commit | cee216a696b2004017a5ecb583366093d90b1568 (patch) | |
tree | 4270e8e8e17a7450395e374b3a10391818d08d45 /mm | |
parent | 3f472cc978ea019c7b09cc03f90b8ed6034efdf8 (diff) | |
download | linux-stable-cee216a696b2004017a5ecb583366093d90b1568.tar.gz linux-stable-cee216a696b2004017a5ecb583366093d90b1568.tar.bz2 linux-stable-cee216a696b2004017a5ecb583366093d90b1568.zip |
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.
[akpm@linux-foundation.org: remove unwanted ppc change, per Aneesh]
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>
Signed-off-by: Linus Torvalds <torvalds@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); |