Re: [PATCH v3 1/4] x86/vm86/32: Switch to flush_tlb_mm_range() in mark_screen_rdonly()

[Nadav Amit]

It may be benign, but I donât 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" <luto@xxxxxxxxxx> 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 <riel@xxxxxxxxxx>
    Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
    Cc: Nadav Amit <namit@xxxxxxxxxx>
    Cc: Michal Hocko <mhocko@xxxxxxxx>
    Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
    Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
    ---
     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