Xen's do_suspend() calls dpm_suspend_start() without taking required system_transition_mutex. Since 12ffc3b1513eb moved the pm_restrict_gfp_mask() call, not taking that mutex results in a WARN.

Take the mutex in do_suspend(), and use mutex_trylock() to follow how enter_state() does this.

Suggested-by: Jürgen Groß jgross@suse.com Fixes: 12ffc3b1513eb "PM: Restrict swap use to later in the suspend sequence" Link: https://lore.kernel.org/xen-devel/aKiBJeqsYx_4Top5@mail-itl/ Signed-off-by: Marek Marczykowski-Górecki marmarek@invisiblethingslab.com Cc: stable@vger.kernel.org # v6.16+ --- drivers/xen/manage.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c index b4b4ebed68daf..f78d970949c0a 100644 --- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -11,6 +11,7 @@ #include <linux/reboot.h> #include <linux/sysrq.h> #include <linux/stop_machine.h> +#include <linux/suspend.h> #include <linux/freezer.h> #include <linux/syscore_ops.h> #include <linux/export.h> @@ -101,10 +102,16 @@ static void do_suspend(void)

shutting_down = SHUTDOWN_SUSPEND;

+ if (!mutex_trylock(&system_transition_mutex)) + { + pr_err("%s: failed to take system_transition_mutex\n", __func__); + goto out; + } + err = freeze_processes(); if (err) { pr_err("%s: freeze processes failed %d\n", __func__, err); - goto out; + goto out_unlock; }

err = freeze_kernel_threads(); @@ -160,6 +167,8 @@ static void do_suspend(void)

out_thaw: thaw_processes(); +out_unlock: + mutex_unlock(&system_transition_mutex); out: shutting_down = SHUTDOWN_INVALID; }