Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6ad8d010b2f364b739020e514e61b6a73444464b
Commit: 6ad8d010b2f364b739020e514e61b6a73444464b
Parent: 988519acb3dbe7168276a36cbb8fd91fddbffaee
Author: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
AuthorDate: Sun May 27 15:18:22 2007 +1000
Committer: Paul Mackerras <[EMAIL PROTECTED]>
CommitDate: Sat Jun 2 21:01:55 2007 +1000
[POWERPC] Fix possible access to free pages
I think we have a subtle race on ppc64 with the tlb batching. The
common code expects tlb_flush() to actually flush any pending TLB
batch. It does that because it delays all page freeing until after
tlb_flush() is called, in order to ensure no stale reference to
those pages exist in any TLB, thus causing potential access to
the freed pages.
However, our tlb_flush only triggers the RCU for freeing page
table pages, it does not currently trigger a flush of a pending
TLB/hash batch, which is, I think, an error. This fixes it.
Signed-off-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
Signed-off-by: Paul Mackerras <[EMAIL PROTECTED]>
---
include/asm-powerpc/tlb.h | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/include/asm-powerpc/tlb.h b/include/asm-powerpc/tlb.h
index 0a17682..6671404 100644
--- a/include/asm-powerpc/tlb.h
+++ b/include/asm-powerpc/tlb.h
@@ -38,6 +38,15 @@ extern void pte_free_finish(void);
static inline void tlb_flush(struct mmu_gather *tlb)
{
+ struct ppc64_tlb_batch *tlbbatch = &__get_cpu_var(ppc64_tlb_batch);
+
+ /* If there's a TLB batch pending, then we must flush it because the
+ * pages are going to be freed and we really don't want to have a CPU
+ * access a freed page because it has a stale TLB
+ */
+ if (tlbbatch->index)
+ __flush_tlb_pending(tlbbatch);
+
pte_free_finish();
}
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
