What about something like this?
---
include/asm-generic/tlb.h | 11 ++++++++++-
mm/memory.c | 17 ++++++++++++++++-
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index b1b1fa6..651b1cf 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -116,6 +116,7 @@ struct mmu_gather {
static inline int tlb_fast_mode(struct mmu_gather *tlb)
{
+#ifndef CONFIG_PREEMPT
#ifdef CONFIG_SMP
return tlb->fast_mode;
#else
@@ -124,7 +125,15 @@ static inline int tlb_fast_mode(struct mmu_gather *tlb)
* and page free order so much..
*/
return 1;
-#endif
+#endif /* CONFIG_SMP */
+#else /* CONFIG_PREEMPT */
+ /*
+ * Since mmu_gather is preemptible, preemptible kernels are like SMP
+ * kernels, we must batch to make sure we invalidate TLBs before we
+ * free the pages.
+ */
+ return 0;
+#endif /* CONFIG_PREEMPT */
}
void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm);
diff --git a/mm/memory.c b/mm/memory.c
index 6dc1882..e915af2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -384,6 +384,21 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
+static inline void cond_resched_tlb(struct mmu_gather *tlb)
+{
+#ifndef CONFIG_PREEMPT
+ /*
+ * For full preempt kernels we must do regular batching like
+ * SMP, see tlb_fast_mode(). For !PREEMPT we can 'cheat' and
+ * do a flush before our voluntary 'yield'.
+ */
+ if (need_resched()) {
+ tlb_flush_mmu(tlb);
+ cond_resched();
+ }
+#endif
+}
+
/*
* If a p?d_bad entry is found while walking page tables, report
* the error, before resetting entry to p?d_none. Usually (but
@@ -1264,7 +1279,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
goto next;
next = zap_pte_range(tlb, vma, pmd, addr, next, details);
next:
- cond_resched();
+ cond_resched_tlb(tlb);
} while (pmd++, addr = next, addr != end);
return addr;
--
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