On Feb 27, 2026 / 20:32, Jaegeuk Kim wrote: > On 02/24, Shinichiro Kawasaki wrote: > > On Feb 24, 2026 / 03:26, Jaegeuk Kim wrote: > > > On 02/18, Shin'ichiro Kawasaki wrote: > > > > From: Shin'ichiro Kawasaki via Linux-f2fs-devel > > > > <[email protected]> > > > > > > > > A lockdep WARN is observed recently under the following steps: > > > > > > > > 1) Create a zoned TCMU device > > > > 2) Create a f2fs filesystem on the zoned TCMU device and mount it > > > > 3) Fill the filesystem with files and trigger GC > > > > 4) Unmout the filesystem > > > > 5) Remove the zoned TCMU device > > > > > > > > The lockdep WARN indicates that a circular lock depedency formed by four > > > > contexts, as described below. > > > > > > > > a) TCMU device removal context: > > > > - call del_gendisk() to get q->q_usage_counter > > > > - call start_flush_work() to get work_completion of wb->dwork > > > > b) f2fs writeback context: > > > > - in wb_workfn(), which holds work_completion of wb->dwork > > > > - call f2fs_balance_fs() to get sbi->gc_lock > > > > c) f2fs vfs_write context: > > > > - call f2fs_gc() to get sbi->gc_lock > > > > - call f2fs_write_checkpoint() to get sbi->cp_global_sem > > > > d) f2fs mount context: > > > > - call recover_fsync_data() to get sbi->cp_global_sem > > > > - call f2fs_check_and_fix_write_pointer() to call blkdev_report_zones() > > > > that goes down to blk_mq_alloc_request and get q->q_usage_counter > > > > > > > > To suppress the WARN, cut the dependency d) between sbi->cp_global_sem > > > > and q->q_usage_counter. For that purpose, move the > > > > f2fs_check_and_fix_write_pointer() call outside of the critical section > > > > of sbi->cp_global_sem in f2fs_recovery_fsync_data(). This change is fine > > > > because the write pointer fix operation only affects the main segments > > > > and does not interact with the check point metadata. Furthermore, > > > > conflicts between the write pointer fix operation and data/node flush > > > > operations remain protected by SBI_POR_DOING. > > > > > > > > Fixes: c426d99127b1 ("f2fs: Check write pointer consistency of open > > > > zones") > > > > Reviewed-by: Damien Le Moal <[email protected]> > > > > Signed-off-by: Shin'ichiro Kawasaki <[email protected]> > > > > --- > > > > fs/f2fs/recovery.c | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c > > > > index a26071f2b0bc..87fd6cd436fe 100644 > > > > --- a/fs/f2fs/recovery.c > > > > +++ b/fs/f2fs/recovery.c > > > > @@ -922,6 +922,8 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info > > > > *sbi, bool check_only) > > > > truncate_inode_pages_final(META_MAPPING(sbi)); > > > > } > > > > > > > > + f2fs_up_write_trace(&sbi->cp_global_sem, &lc); > > > > + > > > > /* > > > > * If fsync data succeeds or there is no fsync data to recover, > > > > * and the f2fs is not read only, check and fix zoned block > > > > devices' > > > > @@ -933,8 +935,6 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info > > > > *sbi, bool check_only) > > > > if (!err) > > > > clear_sbi_flag(sbi, SBI_POR_DOING); > > > > > > > > - f2fs_up_write_trace(&sbi->cp_global_sem, &lc); > > > > - > > > > > > This was a guard to prevent checkpoint during > > > f2fs_check_and_fix_write_pointer() > > > where it changes the checkpoint as well? > > > > I checked f2fs_check_and_fix_write_pointer() again, and it does not look > > changing the checkpoint to me. FYI, here I show the rough function call > > chain > > from f2fs_check_and_fix_write_pointer() as below. I guess this call chain > > does > > not change the checkpoint, but if I misunderstand anything, please let me > > know. > > > > f2fs_check_and_fix_write_pointer() > > fix_curseg_write_pointer() > > do_fix_curseg_write_pointer() > > blkdev_report_zones() > > report_one_zone_cb() > > f2fs_allocate_new_section() > > __allocate_new_segment() > > new_curseg() > > E.g., curseg. >
Thanks, I looked in do_checkpoint() in fs/f2fs/checkpoing.c, and found it refers to cursegs. Then, this patch will allow recording the cursegs in parallel of f2fs_check_and_fix_write_pointer(), and it will results in inconsistent curseg values in checkpoints. Not good. Let me drop this patch. I will seek out other ways to avoid the lockdep. I have no idea how to do that at this moment, though. _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
