Re: [PATCH] mm: do not show ?? for VM_LOCKONFAULT pages

[Vlastimil Babka]

On 12/5/22 18:30, Jason A. Donenfeld wrote:
> When VM_LOCKONFAULT was added, /proc/PID/smaps wasn't hooked up to it,
> so looking at /proc/PID/smaps, it shows '??' instead of something
> intelligable. This can be reached by userspace by simply calling
> `mlock2(..., MLOCK_ONFAULT);`.
> 
> Fix this by adding "lf" to denote VM_LOCKONFAULT.
> 
> Cc: Eric B Munson <emunson@xxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Fixes: de60f5f10c58 ("mm: introduce VM_LOCKONFAULT")
> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
>  fs/proc/task_mmu.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 8a74cdcc9af0..60851e96530b 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -667,6 +667,7 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
>  		[ilog2(VM_RAND_READ)]	= "rr",
>  		[ilog2(VM_DONTCOPY)]	= "dc",
>  		[ilog2(VM_DONTEXPAND)]	= "de",
> +		[ilog2(VM_LOCKONFAULT)]	= "lf",
>  		[ilog2(VM_ACCOUNT)]	= "ac",
>  		[ilog2(VM_NORESERVE)]	= "nr",
>  		[ilog2(VM_HUGETLB)]	= "ht",