| Submitter | David Miller |
|---|---|
| Date | Oct. 2, 2012, 10:27 p.m. |
| Message ID | <20121002.182741.650740858374403508.davem@davemloft.net> |
| Download | mbox | patch |
| Permalink | /patch/188671/ |
| State | RFC |
| Delegated to: | David Miller |
| Headers | show |
Comments
On Tue, Oct 02, 2012 at 06:27:41PM -0400, David Miller wrote: > > Invalidation sequences are handled in various ways on various > architectures. > > One way, which sparc64 uses, is to let the set_*_at() functions > accumulate pending flushes into a per-cpu array. Then the > flush_tlb_range() et al. calls process the pending TLB flushes. > > In this regime, the __tlb_remove_*tlb_entry() implementations are > essentially NOPs. > > The canonical PTE zap in mm/memory.c is: > > ptent = ptep_get_and_clear_full(mm, addr, pte, > tlb->fullmm); > tlb_remove_tlb_entry(tlb, pte, addr); > > With a subsequent tlb_flush_mmu() if needed. > > Mirror this in the THP PMD zapping using: > > orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); > page = pmd_page(orig_pmd); > tlb_remove_pmd_tlb_entry(tlb, pmd, addr); > > And we properly accomodate TLB flush mechanims like the one described > above. Thanks for the explanation. Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Patch
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 5d44785..f9d8461 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1025,9 +1025,10 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, if (__pmd_trans_huge_lock(pmd, vma) == 1) { struct page *page; pgtable_t pgtable; + pmd_t orig_pmd; pgtable = get_pmd_huge_pte(tlb->mm); - page = pmd_page(*pmd); - pmd_clear(pmd); + orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); + page = pmd_page(orig_pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); page_remove_rmap(page); VM_BUG_ON(page_mapcount(page) < 0);
Invalidation sequences are handled in various ways on various architectures. One way, which sparc64 uses, is to let the set_*_at() functions accumulate pending flushes into a per-cpu array. Then the flush_tlb_range() et al. calls process the pending TLB flushes. In this regime, the __tlb_remove_*tlb_entry() implementations are essentially NOPs. The canonical PTE zap in mm/memory.c is: ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); tlb_remove_tlb_entry(tlb, pte, addr); With a subsequent tlb_flush_mmu() if needed. Mirror this in the THP PMD zapping using: orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd); page = pmd_page(orig_pmd); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); And we properly accomodate TLB flush mechanims like the one described above. Signed-off-by: David S. Miller <davem@davemloft.net> --- mm/huge_memory.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)