PM: hibernate: call preallocate_image() after freeze prepare

Certain drivers release resources (pinned pages, etc.) into system
memory during the prepare freeze PM op, making them swappable.
Currently, hibernate_preallocate_memory() is called before prepare
freeze, so those drivers have no opportunity to release resources
first. If a driver is holding a large amount of unswappable system
RAM, this can cause hibernate_preallocate_memory() to fail.

Move the call to hibernate_preallocate_memory() after prepare freeze.

According to the documentation for the prepare callback, devices should
be left in a usable state, so storage drivers should still be able to
service I/O requests. This allows drivers to release unswappable
resources prior to preallocation, so they can be swapped out through
hibernate_preallocate_memory()'s reclaim path.

Also remove shrink_shmem_memory() since hibernate_preallocate_memory()
will have reclaimed enough memory for the hibernation image.

Signed-off-by: Matthew Leach <matthew.leach@collabora.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
[ rjw: Subject and changelog tweaks ]
Link: https://patch.msgid.link/20260403-hibernation-fixes-v3-1-31bc9fa3ba2d@collabora.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index af8d07bafe02a74b400fdce505fba12ad01cd757..d2479c69d71a4c51529e3ce25fd3e2f989244be5 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -392,23 +392,6 @@ 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.
@@ -425,14 +408,9 @@ int hibernation_snapshot(int platform_mode)
        if (error)
                goto Close;
 
-       /* Preallocate image memory before shutting down devices. */
-       error = hibernate_preallocate_memory();
-       if (error)
-               goto Close;
-
        error = freeze_kernel_threads();
        if (error)
-               goto Cleanup;
+               goto Close;
 
        if (hibernation_test(TEST_FREEZER)) {
 
@@ -445,19 +423,13 @@ int hibernation_snapshot(int platform_mode)
        }
 
        error = dpm_prepare(PMSG_FREEZE);
-       if (error) {
-               dpm_complete(PMSG_RECOVER);
-               goto Thaw;
-       }
+       if (error)
+               goto Complete;
 
-       /*
-        * 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();
+       /* Preallocate image memory before shutting down devices. */
+       error = hibernate_preallocate_memory();
+       if (error)
+               goto Complete;
 
        console_suspend_all();
        pm_restrict_gfp_mask();
@@ -492,10 +464,10 @@ int hibernation_snapshot(int platform_mode)
        platform_end(platform_mode);
        return error;
 
+ Complete:
+       dpm_complete(PMSG_RECOVER);
  Thaw:
        thaw_kernel_threads();
- Cleanup:
-       swsusp_free();
        goto Close;
 }