[PATCH] f2fs: fix to freeze GC and discard threads quickly

Daeho Jeong
2026-03-10T20:49:22Z

From: Daeho Jeong <daehojeong@google.com>

Suspend can fail if kernel threads do not freeze for a while.
f2fs_gc and f2fs_discard threads can perform long-running operations
that prevent them from reaching a freeze point in a timely manner.

This patch adds explicit freezing checks in the following locations:
1. f2fs_gc: Added a check at the 'retry' label to exit the loop quickly
if freezing is requested, especially during heavy GC rounds.
2. __issue_discard_cmd: Added a 'suspended' flag to break both inner and
outer loops during discard command issuance if freezing is detected
after at least one command has been issued.
3. __issue_discard_cmd_orderly: Added a similar check for orderly discard
to ensure responsiveness.

These checks ensure that the threads release locks safely and enter the
frozen state.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
fs/f2fs/gc.c | 4 ++++
fs/f2fs/segment.c | 14 ++++++++++++--
2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 981eac629fe9..fdc3366c4db3 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1962,6 +1962,10 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
goto stop;
}
retry:
+ if (unlikely(freezing(current))) {
+ ret = 0;
+ goto stop;
+ }
ret = __get_victim(sbi, &segno, gc_type, gc_control->one_time);
if (ret) {
/* allow to search victim from sections has pinned data */
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index e9b6d774b985..a6c82ab28288 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1606,6 +1606,9 @@ static void __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
if (dc->state != D_PREP)
goto next;

+ if (*issued > 0 && unlikely(freezing(current)))
+ break;
+
if (dpolicy->io_aware && !is_idle(sbi, DISCARD_TIME)) {
io_interrupted = true;
break;
@@ -1645,6 +1648,7 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
struct blk_plug plug;
int i, issued;
bool io_interrupted = false;
+ bool suspended = false;

if (dpolicy->timeout)
f2fs_update_time(sbi, UMOUNT_DISCARD_TIMEOUT);
@@ -1675,6 +1679,11 @@ 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))) {
+ suspended = true;
+ break;
+ }
+
if (dpolicy->timeout &&
f2fs_time_over(sbi, UMOUNT_DISCARD_TIMEOUT))
break;
@@ -1694,11 +1703,12 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
next:
mutex_unlock(&dcc->cmd_lock);

- if (issued >= dpolicy->max_requests || io_interrupted)
+ if (issued >= dpolicy->max_requests || io_interrupted ||
+ suspended)
break;
}

- if (dpolicy->type == DPOLICY_UMOUNT && issued) {
+ if (dpolicy->type == DPOLICY_UMOUNT && issued && !suspended) {
__wait_all_discard_cmd(sbi, dpolicy);
goto retry;
}
--
2.53.0.473.g4a7958ca14-goog