Re: [PATCH 2/5] mm, swap: Use SWP_SOLIDSTATE to determine if swap is rotational

[YoungJun Park <youngjun.park@lge.com>]

On Thu, Oct 30, 2025 at 12:09:29AM +0800, Kairui Song wrote:
> On Wed, Oct 29, 2025 at 05:56:56PM +0800, Youngjun Park wrote:
> > The current non rotational check is unreliable
> > as the device's rotational status can be changed by a user via sysfs.
> > 
> > Use the more reliable SWP_SOLIDSTATE flag which is set at swapon time,
> > to ensure the nr_rotate_swap count remains consistent.
> > Plus, it is easy to read and simple.
> > 
> > Signed-off-by: Youngjun Park <youngjun.park@lge.com>
> > ---
> >  mm/swapfile.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/mm/swapfile.c b/mm/swapfile.c
> > index 6dc0e7a738bc..b5d42918c01b 100644
> > --- a/mm/swapfile.c
> > +++ b/mm/swapfile.c
> > @@ -2913,7 +2913,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
> >  	if (p->flags & SWP_CONTINUED)
> >  		free_swap_count_continuations(p);
> >  
> > -	if (!p->bdev || !bdev_nonrot(p->bdev))
> > +	if (!(p->flags & SWP_SOLIDSTATE))
> >  		atomic_dec(&nr_rotate_swap);
> 
> Good catch.
> 
> Is this introduced by 81a0298bdfab? So we need a Fixes: and backport to stable I think?

Okay, I'll add a Fixes tag :)

Thanks,
Youngjun Park