Patchwork powerpc/mm: Fix SMP issue with MMU context handling code

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Submitter Kumar Gala
Date July 30, 2009, 4:13 a.m.
Message ID <1248927201-18047-1-git-send-email-galak@kernel.crashing.org>
Download mbox | patch
Permalink /patch/30375/
State Accepted
Headers show

Comments

Kumar Gala - July 30, 2009, 4:13 a.m.
In switch_mmu_context() if we call steal_context_smp() to get a context
to use we shouldn't fall through and than call steal_context_up().  Doing
so can be problematic in that the 'mm' that steal_context_up() ends up
using will not get marked dirty in the stale_map[] for other CPUs that
might have used that mm.  Thus we could end up with stale TLB entries in
the other CPUs that can cause all kinda of havoc.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/mm/mmu_context_nohash.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

Patch

diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c
index 92a1971..b1a727d 100644
--- a/arch/powerpc/mm/mmu_context_nohash.c
+++ b/arch/powerpc/mm/mmu_context_nohash.c
@@ -217,6 +217,7 @@  void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
 			id = steal_context_smp(id);
 			if (id == MMU_NO_CONTEXT)
 				goto again;
+			goto stolen;
 		}
 #endif /* CONFIG_SMP */
 		id = steal_context_up(id);