Hi Chao, Could you take a look at this in xfstests/generic/013?
[ 502.480850] ====================================================== [ 502.480864] [ INFO: possible circular locking dependency detected ] [ 502.480877] 4.7.0-rc1+ #124 Tainted: G OE [ 502.480886] ------------------------------------------------------- [ 502.480897] fsstress/10729 is trying to acquire lock: [ 502.480906] (&sb->s_type->i_mutex_key#18){+.+.+.}, at: [<ffffffff81299c3b>] do_blockdev_direct_IO+0x1db/0x2310 [ 502.480948] [ 502.480948] but task is already holding lock: [ 502.480959] (&fi->dio_rwsem){.+.+.+}, at: [<ffffffffc081e2b1>] f2fs_direct_IO+0xd1/0x3d0 [f2fs] [ 502.481003] [ 502.481003] which lock already depends on the new lock. [ 502.481003] [ 502.481018] [ 502.481018] the existing dependency chain (in reverse order) is: [ 502.481030] [ 502.481030] -> #1 (&fi->dio_rwsem){.+.+.+}: [ 502.481054] [<ffffffff810e51c3>] lock_acquire+0xd3/0x220 [ 502.481071] [<ffffffff818d1921>] down_read+0x51/0xa0 [ 502.481089] [<ffffffffc081e2b1>] f2fs_direct_IO+0xd1/0x3d0 [f2fs] [ 502.481114] [<ffffffff811c34c7>] generic_file_direct_write+0xa7/0x160 [ 502.481133] [<ffffffff811c363d>] __generic_file_write_iter+0xbd/0x1e0 [ 502.481149] [<ffffffffc080437b>] f2fs_file_write_iter+0xdb/0x100 [f2fs] [ 502.481173] [<ffffffff81253a88>] __vfs_write+0xc8/0x140 [ 502.481190] [<ffffffff81254c55>] vfs_write+0xb5/0x1b0 [ 502.481205] [<ffffffff81255fe9>] SyS_write+0x49/0xa0 [ 502.481220] [<ffffffff818d4100>] entry_SYSCALL_64_fastpath+0x23/0xc1 [ 502.481236] [ 502.481236] -> #0 (&sb->s_type->i_mutex_key#18){+.+.+.}: [ 502.481264] [<ffffffff810e481c>] __lock_acquire+0x161c/0x1940 [ 502.481280] [<ffffffff810e51c3>] lock_acquire+0xd3/0x220 [ 502.481296] [<ffffffff818d1b9a>] down_write+0x5a/0xc0 [ 502.481312] [<ffffffff81299c3b>] do_blockdev_direct_IO+0x1db/0x2310 [ 502.481328] [<ffffffff8129bdaa>] __blockdev_direct_IO+0x3a/0x40 [ 502.481344] [<ffffffffc081e2e4>] f2fs_direct_IO+0x104/0x3d0 [f2fs] [ 502.481368] [<ffffffff811c40a9>] generic_file_read_iter+0x689/0x7e0 [ 502.481384] [<ffffffff812545d1>] __vfs_read+0xc1/0x130 [ 502.481399] [<ffffffff81254af1>] vfs_read+0x91/0x140 [ 502.481414] [<ffffffff81255f49>] SyS_read+0x49/0xa0 [ 502.481429] [<ffffffff818d4100>] entry_SYSCALL_64_fastpath+0x23/0xc1 [ 502.481445] [ 502.481445] other info that might help us debug this: [ 502.481445] [ 502.481459] Possible unsafe locking scenario: [ 502.481459] [ 502.481726] CPU0 CPU1 [ 502.481987] ---- ---- [ 502.482242] lock(&fi->dio_rwsem); [ 502.482501] lock(&sb->s_type->i_mutex_key#18); [ 502.482765] lock(&fi->dio_rwsem); [ 502.483025] lock(&sb->s_type->i_mutex_key#18); [ 502.483285] [ 502.483285] *** DEADLOCK *** [ 502.483285] [ 502.484018] 1 lock held by fsstress/10729: [ 502.484262] #0: (&fi->dio_rwsem){.+.+.+}, at: [<ffffffffc081e2b1>] f2fs_direct_IO+0xd1/0x3d0 [f2fs] Thanks, On Thu, Jul 07, 2016 at 12:49:12PM +0800, Chao Yu wrote: > From: Chao Yu <yuch...@huawei.com> > > Datas in file can be operated by GC and DIO simultaneously, so we will > face race case as below: > > For write case: > Thread A Thread B > - generic_file_direct_write > - invalidate_inode_pages2_range > - f2fs_direct_IO > - do_blockdev_direct_IO > - do_direct_IO > - get_more_blocks > - f2fs_gc > - do_garbage_collect > - gc_data_segment > - move_data_page > - do_write_data_page > migrate data block to new block > address > - dio_bio_submit > update user data to old block address > > For read case: > Thread A Thread B > - generic_file_direct_write > - invalidate_inode_pages2_range > - f2fs_direct_IO > - do_blockdev_direct_IO > - do_direct_IO > - get_more_blocks > - f2fs_balance_fs > - f2fs_gc > - do_garbage_collect > - gc_data_segment > - move_data_page > - do_write_data_page > migrate data block to new block > address > - write_checkpoint > - do_checkpoint > - clear_prefree_segments > - f2fs_issue_discard > discard old block adress > - dio_bio_submit > update user buffer from obsolete block address > > In order to fix this, for one file, we should let DIO and GC getting exclusion > against with each other. > > Signed-off-by: Chao Yu <yuch...@huawei.com> > --- > v3: use semaphore to avoid racing in between read dio and write dio. > fs/f2fs/data.c | 4 ++++ > fs/f2fs/f2fs.h | 1 + > fs/f2fs/gc.c | 13 +++++++++++++ > fs/f2fs/super.c | 1 + > 4 files changed, 19 insertions(+) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index b6fd5bd..19197bb 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -1712,6 +1712,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, > struct iov_iter *iter) > { > struct address_space *mapping = iocb->ki_filp->f_mapping; > struct inode *inode = mapping->host; > + struct f2fs_inode_info *fi = F2FS_I(inode); > size_t count = iov_iter_count(iter); > loff_t offset = iocb->ki_pos; > int err; > @@ -1727,7 +1728,10 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, > struct iov_iter *iter) > > trace_f2fs_direct_IO_enter(inode, offset, count, iov_iter_rw(iter)); > > + down_read(&fi->dio_rwsem); > err = blockdev_direct_IO(iocb, inode, iter, get_data_block_dio); > + up_read(&fi->dio_rwsem); > + > if (iov_iter_rw(iter) == WRITE) { > if (err > 0) > set_inode_flag(inode, FI_UPDATE_WRITE); > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index bf9a13a..2e439ec 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -474,6 +474,7 @@ struct f2fs_inode_info { > struct list_head inmem_pages; /* inmemory pages managed by f2fs */ > struct mutex inmem_lock; /* lock for inmemory pages */ > struct extent_tree *extent_tree; /* cached extent_tree entry */ > + struct rw_semaphore dio_rwsem; /* avoid racing between dio and gc */ > }; > > static inline void get_extent_info(struct extent_info *ext, > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > index c612137..a9bfb8d 100644 > --- a/fs/f2fs/gc.c > +++ b/fs/f2fs/gc.c > @@ -755,12 +755,25 @@ next_step: > /* phase 3 */ > inode = find_gc_inode(gc_list, dni.ino); > if (inode) { > + struct f2fs_inode_info *fi = F2FS_I(inode); > + bool locked = false; > + > + if (S_ISREG(inode->i_mode)) { > + if (!down_write_trylock(&fi->dio_rwsem)) > + continue; > + locked = true; > + } > + > start_bidx = start_bidx_of_node(nofs, inode) > + ofs_in_node; > if (f2fs_encrypted_inode(inode) && > S_ISREG(inode->i_mode)) > move_encrypted_block(inode, start_bidx); > else > move_data_page(inode, start_bidx, gc_type); > + > + if (locked) > + up_write(&fi->dio_rwsem); > + > stat_inc_data_blk_count(sbi, 1, gc_type); > } > } > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > index edd1b35..dde57fb 100644 > --- a/fs/f2fs/super.c > +++ b/fs/f2fs/super.c > @@ -579,6 +579,7 @@ static struct inode *f2fs_alloc_inode(struct super_block > *sb) > INIT_LIST_HEAD(&fi->gdirty_list); > INIT_LIST_HEAD(&fi->inmem_pages); > mutex_init(&fi->inmem_lock); > + init_rwsem(&fi->dio_rwsem); > > /* Will be used by directory only */ > fi->i_dir_level = F2FS_SB(sb)->dir_level; > -- > 2.7.2