From 050eef364ad700590a605a0749f825cab4834b1e Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Tue, 24 Aug 2010 09:26:21 +0200 Subject: [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 --- arch/s390/include/asm/tlbflush.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'arch/s390/include/asm/tlbflush.h') diff --git a/arch/s390/include/asm/tlbflush.h b/arch/s390/include/asm/tlbflush.h index 304cffa623e..29d5d6d4bec 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); } /* -- cgit v1.2.3