Messages in this thread | | | Date | Mon, 30 May 2022 10:12:48 +0800 | Subject | Re: [PATCH v3 1/3] ext4: fix bug_on ext4_mb_use_inode_pa | From | Baokun Li <> |
| |
在 2022/5/28 23:10, Ritesh Harjani 写道: > On 22/05/28 07:00PM, Baokun Li wrote: >> Hulk Robot reported a BUG_ON: >> ================================================================== >> kernel BUG at fs/ext4/mballoc.c:3211! >> [...] >> RIP: 0010:ext4_mb_mark_diskspace_used.cold+0x85/0x136f >> [...] >> Call Trace: >> ext4_mb_new_blocks+0x9df/0x5d30 >> ext4_ext_map_blocks+0x1803/0x4d80 >> ext4_map_blocks+0x3a4/0x1a10 >> ext4_writepages+0x126d/0x2c30 >> do_writepages+0x7f/0x1b0 >> __filemap_fdatawrite_range+0x285/0x3b0 >> file_write_and_wait_range+0xb1/0x140 >> ext4_sync_file+0x1aa/0xca0 >> vfs_fsync_range+0xfb/0x260 >> do_fsync+0x48/0xa0 >> [...] >> ================================================================== >> >> Above issue may happen as follows: >> ------------------------------------- >> do_fsync >> vfs_fsync_range >> ext4_sync_file >> file_write_and_wait_range >> __filemap_fdatawrite_range >> do_writepages >> ext4_writepages >> mpage_map_and_submit_extent >> mpage_map_one_extent >> ext4_map_blocks >> ext4_mb_new_blocks >> ext4_mb_normalize_request >> >>> start + size <= ac->ac_o_ex.fe_logical >> ext4_mb_regular_allocator >> ext4_mb_simple_scan_group >> ext4_mb_use_best_found >> ext4_mb_new_preallocation >> ext4_mb_new_inode_pa >> ext4_mb_use_inode_pa >> >>> set ac->ac_b_ex.fe_len <= 0 >> ext4_mb_mark_diskspace_used >> >>> BUG_ON(ac->ac_b_ex.fe_len <= 0); >> >> we can easily reproduce this problem with the following commands: >> `fallocate -l100M disk` >> `mkfs.ext4 -b 1024 -g 256 disk` >> `mount disk /mnt` >> `fsstress -d /mnt -l 0 -n 1000 -p 1` >> >> The size must be smaller than or equal to EXT4_BLOCKS_PER_GROUP. >> Therefore, "start + size <= ac->ac_o_ex.fe_logical" may occur >> when the size is truncated. So start should be the start position of >> the group where ac_o_ex.fe_logical is located after alignment. >> In addition, when the value of fe_logical or EXT4_BLOCKS_PER_GROUP >> is very large, the value calculated by start_off is more accurate. >> >> Fixes: cd648b8a8fd5 ("ext4: trim allocation requests to group size") >> Reported-by: Hulk Robot <hulkci@huawei.com> >> Signed-off-by: Baokun Li <libaokun1@huawei.com> >> --- >> V1->V2: >> Replace round_down() with rounddown(). >> Modified comments. >> V2->V3: >> Convert EXT4_BLOCKS_PER_GROUP type to ext4_lblk_t >> to avoid compilation warnings. > Looks good to me. Feel free to add - > > Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com> > >> fs/ext4/mballoc.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> > . > Thank you for your review! -- With Best Regards, Baokun Li
| |