On Fri, Jul 4, 2025 at 12:14 PM Samuel Zhang <guoqing.zh...@amd.com> wrote:
>
> When hibernate with data center dGPUs, huge number of VRAM data will be
> moved to shmem during dev_pm_ops.prepare(). These shmem pages take a lot
> of system memory so that there's no enough free memory for creating the
> hibernation image. This will cause hibernation fail and abort.
>
> After dev_pm_ops.prepare(), call shrink_all_memory() to force move shmem
> pages to swap disk and reclaim the pages, so that there's enough system
> memory for hibernation image and less pages needed to copy to the image.
>
> This patch can only flush and free about half shmem pages. It will be
> better to flush and free more pages, even all of shmem pages, so that
> there're less pages to be copied to the hibernation image and the overall
> hibernation time can be reduced.
>
> Signed-off-by: Samuel Zhang <guoqing.zh...@amd.com>
No fundamental objections from me, so
Acked-by: Rafael J. Wysocki <raf...@kernel.org>
> ---
> kernel/power/hibernate.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 10a01af63a80..7ae9d9a7aa1d 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -370,6 +370,23 @@ static int create_image(int platform_mode)
> return error;
> }
>
> +static void shrink_shmem_memory(void)
> +{
> + struct sysinfo info;
> + unsigned long nr_shmem_pages, nr_freed_pages;
> +
> + si_meminfo(&info);
> + nr_shmem_pages = info.sharedram; /* current page count used for shmem
> */
> + /*
> + * The intent is to reclaim all shmem pages. Though
> shrink_all_memory() can
> + * only reclaim about half of them, it's enough for creating the
> hibernation
> + * image.
> + */
> + nr_freed_pages = shrink_all_memory(nr_shmem_pages);
> + pr_debug("requested to reclaim %lu shmem pages, actually freed %lu
> pages\n",
> + nr_shmem_pages, nr_freed_pages);
> +}
> +
> /**
> * hibernation_snapshot - Quiesce devices and create a hibernation image.
> * @platform_mode: If set, use platform driver to prepare for the transition.
> @@ -411,6 +428,15 @@ int hibernation_snapshot(int platform_mode)
> goto Thaw;
> }
>
> + /*
> + * Device drivers may move lots of data to shmem in dpm_prepare().
> The shmem
> + * pages will use lots of system memory, causing hibernation image
> creation
> + * fail due to insufficient free memory.
> + * This call is to force flush the shmem pages to swap disk and
> reclaim
> + * the system memory so that image creation can succeed.
> + */
> + shrink_shmem_memory();
> +
> suspend_console();
> pm_restrict_gfp_mask();
>
> --
> 2.43.5
>
