linux-kernel - [PATCH] f2fs: ensure node page reads complete before f2fs_put

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Message-ID: <20251006084615.2585252-1-jprusakowski@google.com>
Date: Mon,  6 Oct 2025 10:46:15 +0200
From: Jan Prusakowski <jprusakowski@...gle.com>
To: jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org, 
	Jan Prusakowski <jprusakowski@...gle.com>
Subject: [PATCH] f2fs: ensure node page reads complete before f2fs_put_super() finishes

Xfstests generic/335, generic/336 sometimes crash with the following message:

F2FS-fs (dm-0): detect filesystem reference count leak during umount, type: 9, count: 1
------------[ cut here ]------------
kernel BUG at fs/f2fs/super.c:1939!
Oops: invalid opcode: 0000 [#1] SMP NOPTI
CPU: 1 UID: 0 PID: 609351 Comm: umount Tainted: G        W           6.17.0-rc5-xfstests-g9dd1835ecda5 #1 PREEMPT(none)
Tainted: [W]=WARN
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:f2fs_put_super+0x3b3/0x3c0
Call Trace:
 <TASK>
 generic_shutdown_super+0x7e/0x190
 kill_block_super+0x1a/0x40
 kill_f2fs_super+0x9d/0x190
 deactivate_locked_super+0x30/0xb0
 cleanup_mnt+0xba/0x150
 task_work_run+0x5c/0xa0
 exit_to_user_mode_loop+0xb7/0xc0
 do_syscall_64+0x1ae/0x1c0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
 </TASK>
---[ end trace 0000000000000000 ]---

It appears that sometimes it is possible that f2fs_put_super() is called before
all node page reads are completed.
Adding a call to f2fs_wait_on_all_pages() for F2FS_RD_NODE fixes the problem.

Fixes: bf22c3cc8ce7 ("f2fs: fix the panic in do_checkpoint()")

Signed-off-by: Jan Prusakowski <jprusakowski@...gle.com>
---
 fs/f2fs/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 1e0678e37a30..5c94bc42b8a1 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1976,6 +1976,7 @@ static void f2fs_put_super(struct super_block *sb)
 	f2fs_flush_merged_writes(sbi);
 
 	f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);
+	f2fs_wait_on_all_pages(sbi, F2FS_RD_NODE);
 
 	if (err || f2fs_cp_error(sbi)) {
 		truncate_inode_pages_final(NODE_MAPPING(sbi));
-- 
2.51.0.618.g983fd99d29-goog