Re: [f2fs-dev] [PATCH v2] f2fs: quiesce background threads during system suspend using PM notifier

[Chao Yu <chao@kernel.org>]

On 8/7/26 01:01, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@google.com>
> 
> During system suspend, a race condition can cause f2fs_gc and f2fs_discard
> threads to call submit_bio() while the underlying block device (e.g., UFS)
> is in Runtime PM suspend. Because Runtime PM worker threads are already
> frozen during task freezing, the threads become trapped in
> __bio_queue_enter() waiting on mq_freeze_wq, leading to a PM freezer
> timeout.
> 
> To prevent this deadlock, register a PM notifier to set SBI_IS_SUSPENDING
> during PM_SUSPEND_PREPARE. Background GC and discard threads check this
> flag and immediately stop issuing new bios, allowing them to enter a
> freezable sleep state cleanly before process freezing begins.
> 
> In addition, check freezing() as a fast path to stop issuing new I/O
> when non-PM freezing (e.g. dm-snapshot or cgroup freezer) is requested.
> 
> Signed-off-by: Daeho Jeong <daehojeong@google.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,