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

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Message-ID: <aQEGFWy7AmP2RcVM@google.com>
Date: Tue, 28 Oct 2025 18:06:13 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: Jan Prusakowski <jprusakowski@...gle.com>, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: ensure node page reads complete before
 f2fs_put_super() finishes

Testing this patch:

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: 20872584b8c0b ("f2fs: fix to drop all dirty meta/node pages during umount()")
Signed-off-by: Jan Prusakowski <jprusakowski@...gle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 fs/f2fs/super.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index bdb5ddb4f966..0b0ef8ba243b 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1989,14 +1989,6 @@ static void f2fs_put_super(struct super_block *sb)
 		truncate_inode_pages_final(META_MAPPING(sbi));
 	}
 
-	for (i = 0; i < NR_COUNT_TYPE; i++) {
-		if (!get_pages(sbi, i))
-			continue;
-		f2fs_err(sbi, "detect filesystem reference count leak during "
-			"umount, type: %d, count: %lld", i, get_pages(sbi, i));
-		f2fs_bug_on(sbi, 1);
-	}
-
 	f2fs_bug_on(sbi, sbi->fsync_node_num);
 
 	f2fs_destroy_compress_inode(sbi);
@@ -2007,6 +1999,15 @@ static void f2fs_put_super(struct super_block *sb)
 	iput(sbi->meta_inode);
 	sbi->meta_inode = NULL;
 
+	/* Should check the page counts after dropping all node/meta pages */
+	for (i = 0; i < NR_COUNT_TYPE; i++) {
+		if (!get_pages(sbi, i))
+			continue;
+		f2fs_err(sbi, "detect filesystem reference count leak during "
+			"umount, type: %d, count: %lld", i, get_pages(sbi, i));
+		f2fs_bug_on(sbi, 1);
+	}
+
 	/*
 	 * iput() can update stat information, if f2fs_write_checkpoint()
 	 * above failed with error.
-- 
2.51.1.851.g4ebd6896fd-goog