Thread (16 messages) 16 messages, 2 authors, 2020-04-08

Re: [RFC PATCH v5 4/8] mm: tlb: Pass struct mmu_gather to flush_pmd_tlb_range

From: Peter Zijlstra <peterz@infradead.org>
Date: 2020-03-31 15:14:28
Also in: linux-arch, linux-mm, lkml

On Tue, Mar 31, 2020 at 10:29:23PM +0800, Zhenyu Ye wrote:
quoted hunk ↗ jump to hunk
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index e2e2bef07dd2..32d4661e5a56 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1160,10 +1160,10 @@ static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
  * invalidate the entire TLB which is not desitable.
  * e.g. see arch/arc: flush_pmd_tlb_range
  */
-#define flush_pmd_tlb_range(vma, addr, end)	flush_tlb_range(vma, addr, end)
+#define flush_pmd_tlb_range(tlb, vma, addr, end)	flush_tlb_range(vma, addr, end)
 #define flush_pud_tlb_range(vma, addr, end)	flush_tlb_range(vma, addr, end)
 #else
-#define flush_pmd_tlb_range(vma, addr, end)	BUILD_BUG()
+#define flush_pmd_tlb_range(tlb, vma, addr, end)	BUILD_BUG()
 #define flush_pud_tlb_range(vma, addr, end)	BUILD_BUG()
 #endif
 #endif
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 3d7c01e76efc..96c9cf77bfb5 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -109,8 +109,14 @@ int pmdp_set_access_flags(struct vm_area_struct *vma,
 	int changed = !pmd_same(*pmdp, entry);
 	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 	if (changed) {
+		struct mmu_gather tlb;
+		unsigned long tlb_start = address;
+		unsigned long tlb_end = address + HPAGE_PMD_SIZE;
 		set_pmd_at(vma->vm_mm, address, pmdp, entry);
-		flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+		tlb_gather_mmu(&tlb, vma->vm_mm, tlb_start, tlb_end);
+		tlb.cleared_pmds = 1;
+		flush_pmd_tlb_range(&tlb, vma, tlb_start, tlb_end);
+		tlb_finish_mmu(&tlb, tlb_start, tlb_end);
 	}
 	return changed;
 }
This is madness. Please, carefully consider what you just wrote and what
it will do in the generic case.

Instead of trying to retro-fit flush_*tlb_range() to take an mmu_gather
parameter, please replace them out-right.


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help