[PATCH] f2fs: quiesce background threads during system suspend using PM notifier
From: Daeho Jeong
Date: Wed Jul 29 2026 - 15:32:21 EST
From: Daeho Jeong <daehojeong@xxxxxxxxxx>
During system suspend, a race condition can cause f2fs_gc and f2fs_discard
threads to call submit_bio() while the underlying block device (e.g., UFS)
is in Runtime PM suspend. Because Runtime PM worker threads are already
frozen during task freezing, the threads become trapped in
__bio_queue_enter() waiting on mq_freeze_wq, leading to a PM freezer
timeout.
To prevent this deadlock, register a PM notifier to set SBI_IS_SUSPENDING
during PM_SUSPEND_PREPARE. Background GC and discard threads check this
flag and immediately stop issuing new bios, allowing them to enter a
freezable sleep state cleanly before process freezing begins.
Signed-off-by: Daeho Jeong <daehojeong@xxxxxxxxxx>
---
fs/f2fs/f2fs.h | 3 +++
fs/f2fs/gc.c | 13 ++++++++-----
fs/f2fs/segment.c | 13 +++++++++----
fs/f2fs/super.c | 25 +++++++++++++++++++++++++
4 files changed, 45 insertions(+), 9 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index f24e30bb5c3d..c46bf4df9412 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -25,6 +25,7 @@
#include <linux/quotaops.h>
#include <linux/part_stat.h>
#include <linux/rw_hint.h>
+#include <linux/suspend.h>
#include <linux/fscrypt.h>
#include <linux/fsverity.h>
@@ -1494,6 +1495,7 @@ enum {
SBI_IS_FREEZING, /* freezefs is in process */
SBI_IS_WRITABLE, /* remove ro mountoption transiently */
SBI_ENABLE_CHECKPOINT, /* indicate it's during f2fs_enable_checkpoint() */
+ SBI_IS_SUSPENDING, /* system suspend is in progress */
MAX_SBI_FLAG,
};
@@ -1757,6 +1759,7 @@ struct f2fs_sb_info {
struct f2fs_rwsem sb_lock; /* lock for raw super block */
int valid_super_block; /* valid super block no */
unsigned long s_flag; /* flags for sbi */
+ struct notifier_block pm_nb; /* for PM notifier */
struct mutex writepages; /* mutex for writepages() */
#ifdef CONFIG_BLK_DEV_ZONED
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 93bcb35a5b5d..86b2b29402a5 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -71,7 +71,8 @@ static int gc_thread_func(void *data)
if (kthread_should_stop())
break;
- if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
+ if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE ||
+ is_sbi_flag_set(sbi, SBI_IS_SUSPENDING)) {
increase_sleep_time(gc_th, &wait_ms);
stat_other_skip_bggc_count(sbi);
continue;
@@ -1064,8 +1065,9 @@ static int gc_node_segment(struct f2fs_sb_info *sbi,
struct node_info ni;
int err;
- /* stop BG_GC if there is not enough free sections. */
- if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
+ /* stop BG_GC if there is not enough free sections or suspending. */
+ if (gc_type == BG_GC && (has_not_enough_free_secs(sbi, 0, 0) ||
+ is_sbi_flag_set(sbi, SBI_IS_SUSPENDING)))
return submitted;
if (check_valid_map(sbi, segno, off) == 0)
@@ -1611,7 +1613,8 @@ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
* Or, stop GC if the segment becomes fully valid caused by
* race condition along with SSR block allocation.
*/
- if ((gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0)) ||
+ if ((gc_type == BG_GC && (has_not_enough_free_secs(sbi, 0, 0) ||
+ is_sbi_flag_set(sbi, SBI_IS_SUSPENDING))) ||
(!force_migrate && get_valid_blocks(sbi, segno, true) ==
CAP_BLKS_PER_SEC(sbi)))
return submitted;
@@ -2015,7 +2018,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
goto stop;
}
retry:
- if (unlikely(freezing(current))) {
+ if (is_sbi_flag_set(sbi, SBI_IS_SUSPENDING)) {
ret = 0;
goto stop;
}
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index d70dc5ef3de4..e27197953356 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1300,7 +1300,8 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
if (dc->state != D_PREP)
return 0;
- if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
+ if (is_sbi_flag_set(sbi, SBI_NEED_FSCK) ||
+ is_sbi_flag_set(sbi, SBI_IS_SUSPENDING))
return 0;
#ifdef CONFIG_BLK_DEV_ZONED
@@ -1341,6 +1342,9 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
unsigned long flags;
bool last = true;
+ if (is_sbi_flag_set(sbi, SBI_IS_SUSPENDING))
+ break;
+
if (len > max_discard_blocks) {
len = max_discard_blocks;
last = false;
@@ -1615,7 +1619,7 @@ static void __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
if (dc->state != D_PREP)
goto next;
- if (*issued > 0 && unlikely(freezing(current)))
+ if (is_sbi_flag_set(sbi, SBI_IS_SUSPENDING))
break;
if (dpolicy->io_aware && !is_idle(sbi, DISCARD_TIME)) {
@@ -1688,7 +1692,7 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
list_for_each_entry_safe(dc, tmp, pend_list, list) {
f2fs_bug_on(sbi, dc->state != D_PREP);
- if (issued > 0 && unlikely(freezing(current))) {
+ if (is_sbi_flag_set(sbi, SBI_IS_SUSPENDING)) {
suspended = true;
break;
}
@@ -1955,7 +1959,8 @@ static int issue_discard_thread(void *data)
continue;
if (kthread_should_stop())
return 0;
- if (is_sbi_flag_set(sbi, SBI_NEED_FSCK) ||
+ if (is_sbi_flag_set(sbi, SBI_IS_SUSPENDING) ||
+ is_sbi_flag_set(sbi, SBI_NEED_FSCK) ||
!atomic_read(&dcc->discard_cmd_cnt)) {
wait_ms = dpolicy.max_interval;
continue;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index d5dc83e613e2..536f3ffe5354 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1979,6 +1979,26 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
kvfree(sbi->devs);
}
+static int f2fs_pm_notifier(struct notifier_block *nb,
+ unsigned long action, void *ptr)
+{
+ struct f2fs_sb_info *sbi = container_of(nb, struct f2fs_sb_info, pm_nb);
+
+ switch (action) {
+ case PM_HIBERNATION_PREPARE:
+ case PM_SUSPEND_PREPARE:
+ case PM_RESTORE_PREPARE:
+ set_sbi_flag(sbi, SBI_IS_SUSPENDING);
+ break;
+ case PM_POST_SUSPEND:
+ case PM_POST_HIBERNATION:
+ case PM_POST_RESTORE:
+ clear_sbi_flag(sbi, SBI_IS_SUSPENDING);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
static void f2fs_put_super(struct super_block *sb)
{
struct f2fs_sb_info *sbi = F2FS_SB(sb);
@@ -1986,6 +2006,8 @@ static void f2fs_put_super(struct super_block *sb)
int err = 0;
bool done;
+ unregister_pm_notifier(&sbi->pm_nb);
+
/* unregister procfs/sysfs entries in advance to avoid race case */
f2fs_unregister_sysfs(sbi);
@@ -5472,6 +5494,9 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc)
f2fs_restore_device_alias(sbi);
+ sbi->pm_nb.notifier_call = f2fs_pm_notifier;
+ register_pm_notifier(&sbi->pm_nb);
+
sbi->umount_lock_holder = NULL;
return 0;
--
2.55.0.571.g244d577d93-goog