It may be benign, but I don’t think that flushing the TLB without
holding the ptl or the mmap_sem (for no apparent reason) is a good
practice.

On 4/22/17, 12:01 AM, "Andy Lutomirski" <[email protected]> wrote:

    mark_screen_rdonly() is the last remaining caller of flush_tlb().
    flush_tlb_mm_range() is potentially faster and isn't obsolete.
    
    Compile-tested only because I don't know whether software that uses
    this mechanism even exists.
    
    Cc: Rik van Riel <[email protected]>
    Cc: Dave Hansen <[email protected]>
    Cc: Nadav Amit <[email protected]>
    Cc: Michal Hocko <[email protected]>
    Cc: Sasha Levin <[email protected]>
    Cc: Andrew Morton <[email protected]>
    Signed-off-by: Andy Lutomirski <[email protected]>
    ---
     arch/x86/kernel/vm86_32.c | 2 +-
     1 file changed, 1 insertion(+), 1 deletion(-)
    
    diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
    index 23ee89ce59a9..3eda76b3c835 100644
    --- a/arch/x86/kernel/vm86_32.c
    +++ b/arch/x86/kernel/vm86_32.c
    @@ -193,7 +193,7 @@ static void mark_screen_rdonly(struct mm_struct *mm)
        pte_unmap_unlock(pte, ptl);
     out:
        up_write(&mm->mmap_sem);
    -   flush_tlb();
    +   flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL);
     }
     
     
    -- 
    2.9.3
    
    

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