From: Mel Gorman <[email protected]> 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. [[email protected]: write pte_numa pte back to the page tables] Signed-off-by: Mel Gorman <[email protected]> Signed-off-by: Rik van Riel <[email protected]> Reviewed-by: Rik van Riel <[email protected]> Cc: Alex Thorlton <[email protected]> Cc: Chegu Vinod <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- 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); _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
