From: Baokun Li libaokun1@huawei.com
commit eee22187b53611e173161e38f61de1c7ecbeb876 upstream.
In do_writepages, if the value returned by ext4_writepages is "-ENOMEM" and "wbc->sync_mode == WB_SYNC_ALL", retry until the condition is not met.
In __ext4_get_inode_loc, if the bh returned by sb_getblk is NULL, the function returns -ENOMEM.
In __getblk_slow, if the return value of grow_buffers is less than 0, the function returns NULL.
When the three processes are connected in series like the following stack, an infinite loop may occur:
do_writepages <--- keep retrying ext4_writepages mpage_map_and_submit_extent mpage_map_one_extent ext4_map_blocks ext4_ext_map_blocks ext4_ext_handle_unwritten_extents ext4_ext_convert_to_initialized ext4_split_extent ext4_split_extent_at __ext4_ext_dirty __ext4_mark_inode_dirty ext4_reserve_inode_write ext4_get_inode_loc __ext4_get_inode_loc <--- return -ENOMEM sb_getblk __getblk_gfp __getblk_slow <--- return NULL grow_buffers grow_dev_page <--- return -ENXIO ret = (block < end_block) ? 1 : -ENXIO;
In this issue, bg_inode_table_hi is overwritten as an incorrect value. As a result, `block < end_block` cannot be met in grow_dev_page. Therefore, __ext4_get_inode_loc always returns '-ENOMEM' and do_writepages keeps retrying. As a result, the writeback process is in the D state due to an infinite loop.
Add a check on inode table block in the __ext4_get_inode_loc function by referring to ext4_read_inode_bitmap to avoid this infinite loop.
Cc: stable@kernel.org Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Ritesh Harjani (IBM) ritesh.list@gmail.com Link: https://lore.kernel.org/r/20220817132701.3015912-3-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/inode.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4299,9 +4299,17 @@ static int __ext4_get_inode_loc(struct s inodes_per_block = EXT4_SB(sb)->s_inodes_per_block; inode_offset = ((ino - 1) % EXT4_INODES_PER_GROUP(sb)); - block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block); iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
+ block = ext4_inode_table(sb, gdp); + if ((block <= le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) || + (block >= ext4_blocks_count(EXT4_SB(sb)->s_es))) { + ext4_error(sb, "Invalid inode table block %llu in " + "block_group %u", block, iloc->block_group); + return -EFSCORRUPTED; + } + block += (inode_offset / inodes_per_block); + bh = sb_getblk(sb, block); if (unlikely(!bh)) return -ENOMEM;