FAILED: patch "[PATCH] f2fs: fix potential deadlock in gc_merge path of" failed to apply to 7.1-stable tree

PATCH New [email protected] 2 participants 3 messages Jul 2 – Jul 3

Subsystems (2)

Stable branch F2FS file system

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lore

[email protected]

author maintainer

2026-07-02 13:11 UTC #0 lore raw

The patch below does not apply to the 7.1-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 <[email protected]>.

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-7.1.y
git checkout FETCH_HEAD
git cherry-pick -x 8b4468ec023d0d1b4669dfb867588997cc03a06b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026070240-portal-down-4efd@gregkh' --subject-prefix 'PATCH 7.1.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 <[email protected]>
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 [email protected]

Fixes 351df4b20115 ("f2fs: add segment operations")

Cc Ruipeng Qi <[email protected]>

Reported: Sandeep Dhavale <[email protected]>

Signed-off-by Chao Yu <[email protected]>

Signed-off-by Jaegeuk Kim <[email protected]>

fs/f2fs/segment.c +7 -7

index 7c8ac62b1b0d..1ef4edb77078 100644
@@ -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);

Sasha Levin

maintainer

2026-07-03 14:26 UTC #1 lore raw

PATCH 1/2 f2fs: fix potential deadlock in f2fs_balance_fs()

From: Ruipeng Qi <[email protected]>

[ 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 <[email protected]>

Reviewed-by Chao Yu <[email protected]>

Signed-off-by Ruipeng Qi <[email protected]>

Signed-off-by Jaegeuk Kim <[email protected]>

Stable-dep-of: 8b4468ec023d ("f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()")

Signed-off-by Sasha Levin <[email protected]>

---
 fs/f2fs/data.c    | 29 +++++++++++++++++++++++++++++
 fs/f2fs/f2fs.h    |  1 +
 fs/f2fs/segment.c |  8 ++++++++
 3 files changed, 38 insertions(+)

fs/f2fs/data.c +29 -0

index 8d4f1e75dee3eb..3f9572618f5477 100644
@@ -943,6 +943,35 @@ 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;

fs/f2fs/f2fs.h +1 -0

index 91f506e7c9cfb5..b35bcd61028617 100644
@@ -4153,6 +4153,7 @@ void f2fs_submit_merged_write_folio(struct f2fs_sb_info *sbi,
 				struct folio *folio, enum page_type type);
 void f2fs_submit_merged_ipu_write(struct f2fs_sb_info *sbi,
 					struct bio **bio, struct folio *folio);
+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);

fs/f2fs/segment.c +8 -0

index 788f8b05024927..22a9a7c85ee9a5 100644
@@ -462,6 +462,14 @@ 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_trace(&sbi->gc_lock, &gc_control.lc);
 		stat_inc_gc_call_count(sbi, FOREGROUND);
 		f2fs_gc(sbi, &gc_control);

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-07-03 14:26 UTC #2 lore raw

PATCH 2/2 f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()

From: Chao Yu <[email protected]>

[ Upstream commit 8b4468ec023d0d1b4669dfb867588997cc03a06b ]

When we mount device w/ gc_merge mount option, we may suffer below potential deadlock:

Cc [email protected]

Fixes 351df4b20115 ("f2fs: add segment operations")

Cc Ruipeng Qi <[email protected]>

Reported: Sandeep Dhavale <[email protected]>

Signed-off-by Chao Yu <[email protected]>

Signed-off-by Jaegeuk Kim <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 fs/f2fs/segment.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

fs/f2fs/segment.c +7 -7

index 22a9a7c85ee9a5..c0276a30185602 100644
@@ -444,6 +444,13 @@ 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);

@@ -463,13 +470,6 @@ 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);

Signature · 1 line

2.53.0