* FAILED: patch "[PATCH] f2fs: fix potential deadlock in gc_merge path of" failed to apply to 6.6-stable tree
@ 2026-07-02 13:11 gregkh
2026-07-03 18:38 ` [PATCH 6.6.y 1/2] f2fs: fix potential deadlock in f2fs_balance_fs() Sasha Levin
0 siblings, 1 reply; 3+ messages in thread
From: gregkh @ 2026-07-02 13:11 UTC (permalink / raw)
To: chao, chaseyu, dhavale, jaegeuk, ruipengqi3; +Cc: stable
The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 8b4468ec023d0d1b4669dfb867588997cc03a06b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026070242-popper-obstinate-d622@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 8b4468ec023d0d1b4669dfb867588997cc03a06b Mon Sep 17 00:00:00 2001
From: Chao Yu <chao@kernel.org>
Date: Tue, 19 May 2026 01:14:38 +0000
Subject: [PATCH] f2fs: fix potential deadlock in gc_merge path of
f2fs_balance_fs()
When we mount device w/ gc_merge mount option, we may suffer below
potential deadlock:
Kworker GC trehad Truncator
- f2fs_write_cache_pages
- f2fs_write_single_data_page
- f2fs_do_write_data_page
- folio_start_writeback --- set writeback flag on folio
- f2fs_outplace_write_data
: cached folio in internal bio cache
- f2fs_balance_fs
- wake_up(gc_thread)
: wake up gc thread to run foreground GC
- finish_wait(fggc_wq)
: wait on the waitqueue --- wait on GC thread to finish the work
- truncate_inode_pages_range
- __filemap_get_folio(, FGP_LOCK) --- lock folio
- truncate_inode_partial_folio
- folio_wait_writeback --- wait on writeback being cleared
- do_garbage_collect
- move_data_page
- f2fs_get_lock_data_folio
- lock on folio --- blocked on folio's lock
In order to avoid such deadlock, let's call below functions to commit
cached bios in GC_MERGE path of f2fs_balance_fs() as the same as we did
in NOGC_MERGE path.
- f2fs_submit_merged_write(sbi, DATA);
- f2fs_submit_all_merged_ipu_writes(sbi);
Cc: stable@kernel.org
Fixes: 351df4b20115 ("f2fs: add segment operations")
Cc: Ruipeng Qi <ruipengqi3@gmail.com>
Reported: Sandeep Dhavale <dhavale@google.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Chao Yu <chaseyu@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 7c8ac62b1b0d..1ef4edb77078 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -445,6 +445,13 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
if (has_enough_free_secs(sbi, 0, 0))
return;
+ /*
+ * Submit all cached OPU/IPU DATA bios before triggering
+ * foreground GC to avoid potential deadlocks.
+ */
+ f2fs_submit_merged_write(sbi, DATA);
+ f2fs_submit_all_merged_ipu_writes(sbi);
+
if (test_opt(sbi, GC_MERGE) && sbi->gc_thread &&
sbi->gc_thread->f2fs_gc_task) {
DEFINE_WAIT(wait);
@@ -464,13 +471,6 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
.err_gc_skipped = false,
.nr_free_secs = 1 };
- /*
- * Submit all cached OPU/IPU DATA bios before triggering
- * foreground GC to avoid potential deadlocks.
- */
- f2fs_submit_merged_write(sbi, DATA);
- f2fs_submit_all_merged_ipu_writes(sbi);
-
f2fs_down_write_trace(&sbi->gc_lock, &gc_control.lc);
stat_inc_gc_call_count(sbi, FOREGROUND);
f2fs_gc(sbi, &gc_control);
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 6.6.y 1/2] f2fs: fix potential deadlock in f2fs_balance_fs()
2026-07-02 13:11 FAILED: patch "[PATCH] f2fs: fix potential deadlock in gc_merge path of" failed to apply to 6.6-stable tree gregkh
@ 2026-07-03 18:38 ` Sasha Levin
2026-07-03 18:38 ` [PATCH 6.6.y 2/2] f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs() Sasha Levin
0 siblings, 1 reply; 3+ messages in thread
From: Sasha Levin @ 2026-07-03 18:38 UTC (permalink / raw)
To: stable; +Cc: Ruipeng Qi, Chao Yu, Jaegeuk Kim, Sasha Levin
From: Ruipeng Qi <ruipengqi3@gmail.com>
[ Upstream commit dd3114870771562036fdcf5abe813956f36d224d ]
When the f2fs filesystem space is nearly exhausted, we encounter deadlock
issues as below:
INFO: task A:1890 blocked for more than 120 seconds.
Tainted: G O 6.12.41-g3fe07ddf05ab #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:A state:D stack:0 pid:1890 tgid:1626 ppid:1153 flags:0x00000204
Call trace:
__switch_to+0xf4/0x158
__schedule+0x27c/0x908
schedule+0x3c/0x118
io_schedule+0x44/0x68
folio_wait_bit_common+0x174/0x370
folio_wait_bit+0x20/0x38
folio_wait_writeback+0x54/0xc8
truncate_inode_partial_folio+0x70/0x1e0
truncate_inode_pages_range+0x1b0/0x450
truncate_pagecache+0x54/0x88
f2fs_file_write_iter+0x3e8/0xb80
do_iter_readv_writev+0xf0/0x1e0
vfs_writev+0x138/0x2c8
do_writev+0x88/0x130
__arm64_sys_writev+0x28/0x40
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0xc8/0xf0
do_el0_svc+0x24/0x38
el0_svc+0x30/0xf8
el0t_64_sync_handler+0x120/0x130
el0t_64_sync+0x190/0x198
INFO: task kworker/u8:11:2680853 blocked for more than 120 seconds.
Tainted: G O 6.12.41-g3fe07ddf05ab #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:11 state:D stack:0 pid:2680853 tgid:2680853 ppid:2 flags:0x00000208
Workqueue: writeback wb_workfn (flush-254:0)
Call trace:
__switch_to+0xf4/0x158
__schedule+0x27c/0x908
schedule+0x3c/0x118
io_schedule+0x44/0x68
folio_wait_bit_common+0x174/0x370
__filemap_get_folio+0x214/0x348
pagecache_get_page+0x20/0x70
f2fs_get_read_data_page+0x150/0x3e8
f2fs_get_lock_data_page+0x2c/0x160
move_data_page+0x50/0x478
do_garbage_collect+0xd38/0x1528
f2fs_gc+0x240/0x7e0
f2fs_balance_fs+0x1a0/0x208
f2fs_write_single_data_page+0x6e4/0x730
f2fs_write_cache_pages+0x378/0x9b0
f2fs_write_data_pages+0x2e4/0x388
do_writepages+0x8c/0x2c8
__writeback_single_inode+0x4c/0x498
writeback_sb_inodes+0x234/0x4a8
__writeback_inodes_wb+0x58/0x118
wb_writeback+0x2f8/0x3c0
wb_workfn+0x2c4/0x508
process_one_work+0x180/0x408
worker_thread+0x258/0x368
kthread+0x118/0x128
ret_from_fork+0x10/0x200
INFO: task kworker/u8:8:2641297 blocked for more than 120 seconds.
Tainted: G O 6.12.41-g3fe07ddf05ab #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:8 state:D stack:0 pid:2641297 tgid:2641297 ppid:2 flags:0x00000208
Workqueue: writeback wb_workfn (flush-254:0)
Call trace:
__switch_to+0xf4/0x158
__schedule+0x27c/0x908
rt_mutex_schedule+0x30/0x60
__rt_mutex_slowlock_locked.constprop.0+0x460/0x8a8
rwbase_write_lock+0x24c/0x378
down_write+0x1c/0x30
f2fs_balance_fs+0x184/0x208
f2fs_write_inode+0xf4/0x328
__writeback_single_inode+0x370/0x498
writeback_sb_inodes+0x234/0x4a8
__writeback_inodes_wb+0x58/0x118
wb_writeback+0x2f8/0x3c0
wb_workfn+0x2c4/0x508
process_one_work+0x180/0x408
worker_thread+0x258/0x368
kthread+0x118/0x128
ret_from_fork+0x10/0x20
INFO: task B:1902 blocked for more than 120 seconds.
Tainted: G O 6.12.41-g3fe07ddf05ab #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:B state:D stack:0 pid:1902 tgid:1626 ppid:1153 flags:0x0000020c
Call trace:
__switch_to+0xf4/0x158
__schedule+0x27c/0x908
rt_mutex_schedule+0x30/0x60
__rt_mutex_slowlock_locked.constprop.0+0x460/0x8a8
rwbase_write_lock+0x24c/0x378
down_write+0x1c/0x30
f2fs_balance_fs+0x184/0x208
f2fs_map_blocks+0x94c/0x1110
f2fs_file_write_iter+0x228/0xb80
do_iter_readv_writev+0xf0/0x1e0
vfs_writev+0x138/0x2c8
do_writev+0x88/0x130
__arm64_sys_writev+0x28/0x40
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0xc8/0xf0
do_el0_svc+0x24/0x38
el0_svc+0x30/0xf8
el0t_64_sync_handler+0x120/0x130
el0t_64_sync+0x190/0x198
INFO: task sync:2769849 blocked for more than 120 seconds.
Tainted: G O 6.12.41-g3fe07ddf05ab #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:sync state:D stack:0 pid:2769849 tgid:2769849 ppid:736 flags:0x0000020c
Call trace:
__switch_to+0xf4/0x158
__schedule+0x27c/0x908
schedule+0x3c/0x118
wb_wait_for_completion+0xb0/0xe8
sync_inodes_sb+0xc8/0x2b0
sync_inodes_one_sb+0x24/0x38
iterate_supers+0xa8/0x138
ksys_sync+0x54/0xc8
__arm64_sys_sync+0x18/0x30
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0xc8/0xf0
do_el0_svc+0x24/0x38
el0_svc+0x30/0xf8
el0t_64_sync_handler+0x120/0x130
el0t_64_sync+0x190/0x198
The root cause is a potential deadlock between the following tasks:
kworker/u8:11 Thread A
- f2fs_write_single_data_page
- f2fs_do_write_data_page
- folio_start_writeback(X)
- f2fs_outplace_write_data
- bio_add_folio(X)
- folio_unlock(X)
- truncate_inode_pages_range
- __filemap_get_folio(X, FGP_LOCK)
- truncate_inode_partial_folio(X)
- folio_wait_writeback(X)
- f2fs_balance_fs
- f2fs_gc
- do_garbage_collect
- move_data_page
- f2fs_get_lock_data_page
- __filemap_get_folio(X, FGP_LOCK)
Both threads try to access folio X. Thread A holds the lock but waits
for writeback, while kworker waits for the lock. This causes a deadlock.
Other threads also enter D state, waiting for locks such as gc_lock and
writepages.
OPU/IPU DATA folio are all affected by this issue. To avoid such
potential deadlocks, always commit these cached folios before
triggering f2fs_gc() in f2fs_balance_fs().
Suggested-by: Chao Yu <chao@kernel.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Ruipeng Qi <ruipengqi3@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Stable-dep-of: 8b4468ec023d ("f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/data.c | 29 +++++++++++++++++++++++++++++
fs/f2fs/f2fs.h | 1 +
fs/f2fs/segment.c | 8 ++++++++
3 files changed, 38 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 7643c1d7dbb273..85800d27bb11ce 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -887,6 +887,35 @@ void f2fs_submit_merged_ipu_write(struct f2fs_sb_info *sbi,
}
}
+void f2fs_submit_all_merged_ipu_writes(struct f2fs_sb_info *sbi)
+{
+ struct bio_entry *be, *tmp;
+ struct f2fs_bio_info *io;
+ enum temp_type temp;
+
+ for (temp = HOT; temp < NR_TEMP_TYPE; temp++) {
+ LIST_HEAD(list);
+
+ io = sbi->write_io[DATA] + temp;
+
+ /* A lockless list_empty() check is safe here: any bios from
+ * other kworkers that we miss will be submitted by those
+ * kworkers accordingly.
+ */
+ if (list_empty(&io->bio_list))
+ continue;
+
+ f2fs_down_write(&io->bio_list_lock);
+ list_splice_init(&io->bio_list, &list);
+ f2fs_up_write(&io->bio_list_lock);
+
+ list_for_each_entry_safe(be, tmp, &list, list) {
+ f2fs_submit_write_bio(sbi, be->bio, DATA);
+ del_bio_entry(be);
+ }
+ }
+}
+
int f2fs_merge_page_bio(struct f2fs_io_info *fio)
{
struct bio *bio = *fio->bio;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 50847fd7e55045..63d3450f895eeb 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3866,6 +3866,7 @@ void f2fs_submit_merged_write_cond(struct f2fs_sb_info *sbi,
nid_t ino, enum page_type type);
void f2fs_submit_merged_ipu_write(struct f2fs_sb_info *sbi,
struct bio **bio, struct page *page);
+void f2fs_submit_all_merged_ipu_writes(struct f2fs_sb_info *sbi);
void f2fs_flush_merged_writes(struct f2fs_sb_info *sbi);
int f2fs_submit_page_bio(struct f2fs_io_info *fio);
int f2fs_merge_page_bio(struct f2fs_io_info *fio);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8791aba087cd52..334eb4d81bd671 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -450,6 +450,14 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
.should_migrate_blocks = false,
.err_gc_skipped = false,
.nr_free_secs = 1 };
+
+ /*
+ * Submit all cached OPU/IPU DATA bios before triggering
+ * foreground GC to avoid potential deadlocks.
+ */
+ f2fs_submit_merged_write(sbi, DATA);
+ f2fs_submit_all_merged_ipu_writes(sbi);
+
f2fs_down_write(&sbi->gc_lock);
stat_inc_gc_call_count(sbi, FOREGROUND);
f2fs_gc(sbi, &gc_control);
--
2.53.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 6.6.y 2/2] f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()
2026-07-03 18:38 ` [PATCH 6.6.y 1/2] f2fs: fix potential deadlock in f2fs_balance_fs() Sasha Levin
@ 2026-07-03 18:38 ` Sasha Levin
0 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2026-07-03 18:38 UTC (permalink / raw)
To: stable; +Cc: Chao Yu, stable, Ruipeng Qi, Chao Yu, Jaegeuk Kim, Sasha Levin
From: Chao Yu <chao@kernel.org>
[ Upstream commit 8b4468ec023d0d1b4669dfb867588997cc03a06b ]
When we mount device w/ gc_merge mount option, we may suffer below
potential deadlock:
Kworker GC trehad Truncator
- f2fs_write_cache_pages
- f2fs_write_single_data_page
- f2fs_do_write_data_page
- folio_start_writeback --- set writeback flag on folio
- f2fs_outplace_write_data
: cached folio in internal bio cache
- f2fs_balance_fs
- wake_up(gc_thread)
: wake up gc thread to run foreground GC
- finish_wait(fggc_wq)
: wait on the waitqueue --- wait on GC thread to finish the work
- truncate_inode_pages_range
- __filemap_get_folio(, FGP_LOCK) --- lock folio
- truncate_inode_partial_folio
- folio_wait_writeback --- wait on writeback being cleared
- do_garbage_collect
- move_data_page
- f2fs_get_lock_data_folio
- lock on folio --- blocked on folio's lock
In order to avoid such deadlock, let's call below functions to commit
cached bios in GC_MERGE path of f2fs_balance_fs() as the same as we did
in NOGC_MERGE path.
- f2fs_submit_merged_write(sbi, DATA);
- f2fs_submit_all_merged_ipu_writes(sbi);
Cc: stable@kernel.org
Fixes: 351df4b20115 ("f2fs: add segment operations")
Cc: Ruipeng Qi <ruipengqi3@gmail.com>
Reported: Sandeep Dhavale <dhavale@google.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Chao Yu <chaseyu@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/segment.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 334eb4d81bd671..9c27353f384beb 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -433,6 +433,13 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
if (has_enough_free_secs(sbi, 0, 0))
return;
+ /*
+ * Submit all cached OPU/IPU DATA bios before triggering
+ * foreground GC to avoid potential deadlocks.
+ */
+ f2fs_submit_merged_write(sbi, DATA);
+ f2fs_submit_all_merged_ipu_writes(sbi);
+
if (test_opt(sbi, GC_MERGE) && sbi->gc_thread &&
sbi->gc_thread->f2fs_gc_task) {
DEFINE_WAIT(wait);
@@ -451,13 +458,6 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
.err_gc_skipped = false,
.nr_free_secs = 1 };
- /*
- * Submit all cached OPU/IPU DATA bios before triggering
- * foreground GC to avoid potential deadlocks.
- */
- f2fs_submit_merged_write(sbi, DATA);
- f2fs_submit_all_merged_ipu_writes(sbi);
-
f2fs_down_write(&sbi->gc_lock);
stat_inc_gc_call_count(sbi, FOREGROUND);
f2fs_gc(sbi, &gc_control);
--
2.53.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-07-03 18:38 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2026-07-02 13:11 FAILED: patch "[PATCH] f2fs: fix potential deadlock in gc_merge path of" failed to apply to 6.6-stable tree gregkh
2026-07-03 18:38 ` [PATCH 6.6.y 1/2] f2fs: fix potential deadlock in f2fs_balance_fs() Sasha Levin
2026-07-03 18:38 ` [PATCH 6.6.y 2/2] f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs() Sasha Levin
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