PM: hibernate: Restrict GFP mask in hibernation_snapshot()

Commit 12ffc3b ("PM: Restrict swap use to later in the suspend
sequence") incorrectly removed a pm_restrict_gfp_mask() call from
hibernation_snapshot(), so memory allocations involving swap are not
prevented from being carried out in this code path any more which may
lead to serious breakage.

The symptoms of such breakage have become visible after adding a
shrink_shmem_memory() call to hibernation_snapshot() in commit
2640e81 ("PM: hibernate: shrink shmem pages after dev_pm_ops.prepare()")
which caused this problem to be much more likely to manifest itself.

However, since commit 2640e81 was initially present in the DRM
tree that did not include commit 12ffc3b, the symptoms of this
issue were not visible until merge commit 260f6f4 ("Merge tag
'drm-next-2025-07-30' of https://gitlab.freedesktop.org/drm/kernel")
that exposed it through an entirely reasonable merge conflict
resolution.

Fixes: 12ffc3b ("PM: Restrict swap use to later in the suspend sequence")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220555
Reported-by: Todd Brandt <[email protected]>
Tested-by: Todd Brandt <[email protected]>
Cc: 6.16+ <[email protected]> # 6.16+
Signed-off-by: Rafael J. Wysocki <[email protected]>
Reviewed-by: Mario Limonciello (AMD) <[email protected]>

Author: rafaeljw

kernel/power/hibernate.c

@@ -449,6 +449,7 @@ int hibernation_snapshot(int platform_mode)
 	shrink_shmem_memory();
 
 	console_suspend_all();
+	pm_restrict_gfp_mask();
 
 	error = dpm_suspend(PMSG_FREEZE);