From cfbb1426bd76c4ba6ec4491c8df2a5dd3d984750 Mon Sep 17 00:00:00 2001 From: Jack Steiner Date: Thu, 22 Dec 2005 13:45:41 -0600 Subject: [PATCH] [IA64] Hole in IA64 TLB flushing from system threads I originally thought this was an bug only in the SN code, but I think I also see a hole in the generic IA64 tlb code. (Separate patch was sent for the SN problem). It looks like there is a bug in the TLB flushing code. During context switch, kernel threads (kswapd, for example) inherit the mm of the task that was previously running on the cpu. Normally, this is ok because the previous context is still loaded into the RR registers. However, if the owner of the mm migrates to another cpu, changes it's context number, and references a page before kswapd issues a tlb_purge for that same page, the purge will be done with a stale context number (& RR registers). Signed-off-by: Tony Luck --- arch/ia64/mm/tlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c index 41105d454423..6a4eec9113e8 100644 --- a/arch/ia64/mm/tlb.c +++ b/arch/ia64/mm/tlb.c @@ -90,7 +90,7 @@ ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start, { static DEFINE_SPINLOCK(ptcg_lock); - if (mm != current->active_mm) { + if (mm != current->active_mm || !current->mm) { flush_tlb_all(); return; } -- 2.34.1