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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2010-08-24 11:26:21 +0400
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2010-08-24 11:26:34 +0400
commit050eef364ad700590a605a0749f825cab4834b1e (patch)
tree2714c9cf7edcbf394971cc2c929e5ab2ea34d6a6 /arch/s390/include/asm/tlbflush.h
parent7af048dc7639db5202c56fecf2346c310647a218 (diff)
downloadlinux-050eef364ad700590a605a0749f825cab4834b1e.tar.xz
[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/include/asm/tlbflush.h')
-rw-r--r--arch/s390/include/asm/tlbflush.h6
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/s390/include/asm/tlbflush.h b/arch/s390/include/asm/tlbflush.h
index 304cffa623e1..29d5d6d4becc 100644
--- a/arch/s390/include/asm/tlbflush.h
+++ b/arch/s390/include/asm/tlbflush.h
@@ -94,8 +94,12 @@ static inline void __tlb_flush_mm(struct mm_struct * mm)
static inline void __tlb_flush_mm_cond(struct mm_struct * mm)
{
- if (atomic_read(&mm->mm_users) <= 1 && mm == current->active_mm)
+ spin_lock(&mm->page_table_lock);
+ if (mm->context.flush_mm) {
__tlb_flush_mm(mm);
+ mm->context.flush_mm = 0;
+ }
+ spin_unlock(&mm->page_table_lock);
}
/*