Re: [RFC PATCH 0/2] kernel/power: fix swap device reference handling in hibernation swap path

[Usama Arif <usama.arif@linux.dev>]

On Tue,  3 Mar 2026 01:53:32 +0900 Youngjun Park <youngjun.park@lge.com> wrote:

> This series addresses two issues in the hibernation swap path.
> 
> First, grabbing and releasing the swap device reference on every slot
> allocation is inefficient across the entire hibernation swap path.
> 
> Second, in the uswsusp path, only the swap type value is retrieved at
> lookup time without holding a reference. If swapoff races after the
> type is acquired, subsequent slot allocations operate on a stale swap
> device.
> 
> The fix is to hold the swap device reference from the point the swap
> device is looked up, and release it once at each exit path.
> 
>   Patch 1: Release the reference immediately after each slot allocation
>             as a preparatory step.
>   Patch 2: Lift the reference acquisition to the lookup site and place
>             put_swap_device_by_type() at all relevant cleanup paths in
>             swap.c and user.c.

Hello!

I cant comment on the feasibility of the approach, but for proper series,
you would need to squash the 2 commits, otherwise it would break git
bisectability.

Thanks