Commit 35e4a69b authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: sleep: Allow pm_restrict_gfp_mask() stacking 



Allow pm_restrict_gfp_mask() to be called many times in a row to avoid
issues with calling dpm_suspend_start() when the GFP mask has been
already restricted.

Only the first invocation of pm_restrict_gfp_mask() will actually
restrict the GFP mask and the subsequent calls will warn if there is
a mismatch between the expected allowed GFP mask and the actual one.

Moreover, if pm_restrict_gfp_mask() is called many times in a row,
pm_restore_gfp_mask() needs to be called matching number of times in
a row to actually restore the GFP mask.  Calling it when the GFP mask
has not been restricted will cause it to warn.

This is necessary for the GFP mask restriction starting in
hibernation_snapshot() to continue throughout the entire hibernation
flow until it completes or it is aborted (either by a wakeup event or
by an error).

Fixes: 449c9c02 ("PM: hibernate: Restrict GFP mask in hibernation_snapshot()")
Fixes: 469d80a3 ("PM: hibernate: Fix hybrid-sleep")
Reported-by: default avatarAskar Safin <safinaskar@gmail.com>
Closes: https://lore.kernel.org/linux-pm/20251025050812.421905-1-safinaskar@gmail.com/
Link: https://lore.kernel.org/linux-pm/20251028111730.2261404-1-safinaskar@gmail.com/


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarMario Limonciello (AMD) <superm1@kernel.org>
Tested-by: default avatarMario Limonciello (AMD) <superm1@kernel.org>
Cc: 6.16+ <stable@vger.kernel.org> # 6.16+
Link: https://patch.msgid.link/5935682.DvuYhMxLoT@rafael.j.wysocki
parent 79816d4b

kernel/power/hibernate.c

+0 −4
Original line number Diff line number Diff line
@@ -706,7 +706,6 @@ static void power_down(void) 


#ifdef CONFIG_SUSPEND

	if (hibernation_mode == HIBERNATION_SUSPEND) {

		pm_restore_gfp_mask();

		error = suspend_devices_and_enter(mem_sleep_current);

		if (!error)

			goto exit;
@@ -746,9 +745,6 @@ static void power_down(void) 
		cpu_relax();



exit:

	/* Match the pm_restore_gfp_mask() call in hibernate(). */

	pm_restrict_gfp_mask();



	/* Restore swap signature. */

	error = swsusp_unmark();

	if (error)

kernel/power/main.c

+17 −5
Original line number Diff line number Diff line
@@ -31,23 +31,35 @@ 
 * held, unless the suspend/hibernate code is guaranteed not to run in parallel

 * with that modification).

 */

static unsigned int saved_gfp_count;

static gfp_t saved_gfp_mask;



void pm_restore_gfp_mask(void)

{

	WARN_ON(!mutex_is_locked(&system_transition_mutex));

	if (saved_gfp_mask) {



	if (WARN_ON(!saved_gfp_count) || --saved_gfp_count)

		return;



	gfp_allowed_mask = saved_gfp_mask;

	saved_gfp_mask = 0;

	}



	pm_pr_dbg("GFP mask restored\n");

}



void pm_restrict_gfp_mask(void)

{

	WARN_ON(!mutex_is_locked(&system_transition_mutex));

	WARN_ON(saved_gfp_mask);



	if (saved_gfp_count++) {

		WARN_ON((saved_gfp_mask & ~(__GFP_IO | __GFP_FS)) != gfp_allowed_mask);

		return;

	}



	saved_gfp_mask = gfp_allowed_mask;

	gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);



	pm_pr_dbg("GFP mask restricted\n");

}



unsigned int lock_system_sleep(void)