The patch titled
Subject: mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd().
has been added to the -mm tree. Its filename is
mm-thp-use-more-portable-pmd-clearing-sequenece-in-zap_huge_pmd.patch
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From: David Miller <davem@xxxxxxxxxxxxx>
Subject: mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd().
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@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff -puN mm/huge_memory.c~mm-thp-use-more-portable-pmd-clearing-sequenece-in-zap_huge_pmd mm/huge_memory.c
--- a/mm/huge_memory.c~mm-thp-use-more-portable-pmd-clearing-sequenece-in-zap_huge_pmd
+++ a/mm/huge_memory.c
@@ -1093,9 +1093,10 @@ int zap_huge_pmd(struct mmu_gather *tlb,
if (__pmd_trans_huge_lock(pmd, vma) == 1) {
struct page *page;
pgtable_t pgtable;
+ pmd_t orig_pmd;
pgtable = pgtable_trans_huge_withdraw(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);
_
Patches currently in -mm which might be from davem@xxxxxxxxxxxxx are
origin.patch
linux-next.patch
kconfig-clean-up-the-long-arch-list-for-the-uid16-config-option.patch
kconfig-clean-up-the-long-arch-list-for-the-debug_kmemleak-config-option.patch
kconfig-clean-up-the-long-arch-list-for-the-debug_bugverbose-config-option.patch
kconfig-clean-up-the-if-definedarch-list-for-exception-trace-sysctl-entry.patch
atomic-implement-generic-atomic_dec_if_positive.patch
atomic-implement-generic-atomic_dec_if_positive-fix.patch
sparc64-only-support-4mb-huge-pages-and-8kb-base-pages.patch
sparc64-halve-the-size-of-pte-tables.patch
sparc64-eliminate-pte-table-memory-wastage.patch
sparc64-document-pgd-and-pmd-layout.patch
mm-add-and-use-update_mmu_cache_pmd-in-transparent-huge-page-code.patch
mm-add-and-use-update_mmu_cache_pmd-in-transparent-huge-page-code-fix.patch
mm-thp-use-more-portable-pmd-clearing-sequenece-in-zap_huge_pmd.patch
sparc64-support-transparent-huge-pages.patch
compat-generic-compat_sys_sched_rr_get_interval-implementation.patch
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