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[IA64-SGI] Missed TLB flush 

I see why the problem exists only on SN. SN uses a different hardware
mechanism to purge TLB entries across nodes.

It looks like there is a bug in the SN TLB flushing code. During context switch,
kernel threads inherit the mm of the task that was previously running on the
cpu. This confuses the code in sn2_global_tlb_purge().

The result is a missed TLB purge for the task that owns the "borrowed" mm.

(I hit the problem running heavy stress where kswapd was purging code pages of
a user task that woke kswapd. The user task took a SIGILL fault trying to
execute code in the page that had been ripped out from underneath it).

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Jack Steiner 2005-12-15 12:41:22 -06:00 committed by Tony Luck
parent 3bd7f01713
commit d74700e604
1 changed files with 1 additions and 1 deletions
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2
arch/ia64/sn/kernel/sn2/sn2_smp.c
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@ -202,7 +202,7 @@ sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long nbits)
{
int i, opt, shub1, cnode, mynasid, cpu, lcpu = 0, nasid, flushed = 0;
int mymm = (mm == current->active_mm);
int mymm = (mm == current->active_mm && current->mm);
volatile unsigned long *ptc0, *ptc1;
unsigned long itc, itc2, flags, data0 = 0, data1 = 0, rr_value;
short nasids[MAX_NUMNODES], nix;