linux-kernel - [PATCH v1] PM: hibernate: Restrict GFP mask in hibernation

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Message-ID: <5924662.DvuYhMxLoT@rafael.j.wysocki>
Date: Wed, 10 Sep 2025 11:41:59 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Mario Limonciello <mario.limonciello@....com>,
 Todd Brandt <todd.e.brandt@...ux.intel.com>,
 Linus Torvalds <torvalds@...uxfoundation.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Samuel Zhang <guoqing.zhang@....com>
Subject: [PATCH v1] PM: hibernate: Restrict GFP mask in hibernation_snapshot()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Commit 12ffc3b1513e ("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
2640e819474f ("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 2640e819474f was initially present in the DRM
tree that did not include commit 12ffc3b1513e, the symptoms of this
issue were not visible until merge commit 260f6f4fda93 ("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: 12ffc3b1513e ("PM: Restrict swap use to later in the suspend sequence")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220555
Reported-by: Todd Brandt <todd.e.brandt@...ux.intel.com>
Tested-by: Todd Brandt <todd.e.brandt@...ux.intel.com>
Cc: 6.16+ <stable@...r.kernel.org> # 6.16+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

This is super-urgent, so I'm going to fast-track it.

---
 kernel/power/hibernate.c |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -449,6 +449,7 @@ int hibernation_snapshot(int platform_mo
 	shrink_shmem_memory();

 	console_suspend_all();
+	pm_restrict_gfp_mask();

 	error = dpm_suspend(PMSG_FREEZE);