From: Jason Xing <kerneljasonxing@gmail.com>
To: tytso@mit.edu, adilger.kernel@dilger.ca
Cc: linux-ext4@vger.kernel.org, kerneljasonxing@gmail.com,
Jason Xing <kernelxing@tencent.com>
Subject: [PATCH] ext4: fix a data-race around bg_free_blocks_count_lo
Date: Sun, 12 May 2024 14:42:03 +0800 [thread overview]
Message-ID: <20240512064203.63067-2-kerneljasonxing@gmail.com> (raw)
In-Reply-To: <20240512064203.63067-1-kerneljasonxing@gmail.com>
From: Jason Xing <kernelxing@tencent.com>
KCSAN reported a data-race issue due to two different cpus accessing
this member.
BUG: KCSAN: data-race in ext4_free_inodes_count / ext4_free_inodes_set
write to 0xffff888104a9e00e of 2 bytes by task 4435 on cpu 0:
ext4_free_inodes_set+0x1f/0x80 fs/ext4/super.c:397
__ext4_new_inode+0x15c8/0x2290 fs/ext4/ialloc.c:1216
ext4_symlink+0x242/0x580 fs/ext4/namei.c:3393
vfs_symlink+0xc2/0x1a0 fs/namei.c:4475
do_symlinkat+0xe3/0x320 fs/namei.c:4501
__do_sys_symlinkat fs/namei.c:4517 [inline]
__se_sys_symlinkat fs/namei.c:4514 [inline]
__x64_sys_symlinkat+0x62/0x70 fs/namei.c:4514
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
read to 0xffff888104a9e00e of 2 bytes by task 4440 on cpu 1:
ext4_free_inodes_count+0x1c/0x80 fs/ext4/super.c:341
__ext4_new_inode+0xb71/0x2290 fs/ext4/ialloc.c:1040
ext4_symlink+0x242/0x580 fs/ext4/namei.c:3393
vfs_symlink+0xc2/0x1a0 fs/namei.c:4475
do_symlinkat+0xe3/0x320 fs/namei.c:4501
__do_sys_symlinkat fs/namei.c:4517 [inline]
__se_sys_symlinkat fs/namei.c:4514 [inline]
__x64_sys_symlinkat+0x62/0x70 fs/namei.c:4514
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
value changed: 0x185c -> 0x185b
Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
fs/ext4/super.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index cf817a6a6e27..6db71cc1e5cd 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -338,7 +338,7 @@ ext4_fsblk_t ext4_inode_table(struct super_block *sb,
__u32 ext4_free_group_clusters(struct super_block *sb,
struct ext4_group_desc *bg)
{
- return le16_to_cpu(bg->bg_free_blocks_count_lo) |
+ return le16_to_cpu(READ_ONCE(bg->bg_free_blocks_count_lo)) |
(EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ?
(__u32)le16_to_cpu(bg->bg_free_blocks_count_hi) << 16 : 0);
}
@@ -394,7 +394,7 @@ void ext4_inode_table_set(struct super_block *sb,
void ext4_free_group_clusters_set(struct super_block *sb,
struct ext4_group_desc *bg, __u32 count)
{
- bg->bg_free_blocks_count_lo = cpu_to_le16((__u16)count);
+ WRITE_ONCE(bg->bg_free_blocks_count_lo, cpu_to_le16((__u16)count));
if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT)
bg->bg_free_blocks_count_hi = cpu_to_le16(count >> 16);
}
--
2.37.3
prev parent reply other threads:[~2024-05-12 6:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-12 6:42 [PATCH] ext4: fix a data-race around bg_free_inodes_count_lo Jason Xing
2024-05-12 6:42 ` Jason Xing [this message]
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