From: Mel Gorman <mgorman@xxxxxxx>
Subject: mm: numa: do not clear PTE for pte_numa update
The TLB must be flushed if the PTE is updated but change_pte_range is
clearing the PTE while marking PTEs pte_numa without necessarily flushing
the TLB if it reinserts the same entry. Without the flush, it's
conceivable that two processors have different TLBs for the same virtual
address and at the very least it would generate spurious faults. This
patch only unmaps the pages in change_pte_range for a full protection
change.
[riel@xxxxxxxxxx: write pte_numa pte back to the page tables]
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Alex Thorlton <athorlton@xxxxxxx>
Cc: Chegu Vinod <chegu_vinod@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mprotect.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff -puN mm/mprotect.c~mm-numa-do-not-clear-pte-for-pte_numa-update mm/mprotect.c
--- a/mm/mprotect.c~mm-numa-do-not-clear-pte-for-pte_numa-update
+++ a/mm/mprotect.c
@@ -52,17 +52,19 @@ static unsigned long change_pte_range(st
pte_t ptent;
bool updated = false;
- ptent = ptep_modify_prot_start(mm, addr, pte);
if (!prot_numa) {
+ ptent = ptep_modify_prot_start(mm, addr, pte);
ptent = pte_modify(ptent, newprot);
updated = true;
} else {
struct page *page;
+ ptent = *pte;
page = vm_normal_page(vma, addr, oldpte);
if (page) {
if (!pte_numa(oldpte)) {
ptent = pte_mknuma(ptent);
+ set_pte_at(mm, addr, pte, ptent);
updated = true;
}
}
@@ -79,7 +81,10 @@ static unsigned long change_pte_range(st
if (updated)
pages++;
- ptep_modify_prot_commit(mm, addr, pte, ptent);
+
+ /* Only !prot_numa always clears the pte */
+ if (!prot_numa)
+ ptep_modify_prot_commit(mm, addr, pte, ptent);
} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
swp_entry_t entry = pte_to_swp_entry(oldpte);
_
--
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