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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2010-08-24 09:26:21 +0200
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2010-08-24 09:26:34 +0200
commit050eef364ad700590a605a0749f825cab4834b1e (patch)
tree2714c9cf7edcbf394971cc2c929e5ab2ea34d6a6 /arch/s390/kernel
parent7af048dc7639db5202c56fecf2346c310647a218 (diff)
[S390] fix tlb flushing vs. concurrent /proc accesses
The tlb flushing code uses the mm_users field of the mm_struct to decide if each page table entry needs to be flushed individually with IPTE or if a global flush for the mm_struct is sufficient after all page table updates have been done. The comment for mm_users says "How many users with user space?" but the /proc code increases mm_users after it found the process structure by pid without creating a new user process. Which makes mm_users useless for the decision between the two tlb flusing methods. The current code can be confused to not flush tlb entries by a concurrent access to /proc files if e.g. a fork is in progres. The solution for this problem is to make the tlb flushing logic independent from the mm_users field. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel')
-rw-r--r--arch/s390/kernel/smp.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 541053ed234e..8127ebd59c4d 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -583,6 +583,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
sf->gprs[9] = (unsigned long) sf;
cpu_lowcore->save_area[15] = (unsigned long) sf;
__ctl_store(cpu_lowcore->cregs_save_area, 0, 15);
+ atomic_inc(&init_mm.context.attach_count);
asm volatile(
" stam 0,15,0(%0)"
: : "a" (&cpu_lowcore->access_regs_save_area) : "memory");
@@ -659,6 +660,7 @@ void __cpu_die(unsigned int cpu)
while (sigp_p(0, cpu, sigp_set_prefix) == sigp_busy)
udelay(10);
smp_free_lowcore(cpu);
+ atomic_dec(&init_mm.context.attach_count);
pr_info("Processor %d stopped\n", cpu);
}