Thanks, I'll update the patch.
On Thu, May 5, 2022 at 11:40 PM Jan Kara <jack@xxxxxxx> wrote:
>
> On Thu 05-05-22 21:47:31, Jing Xia wrote:
> > We have run into an issue that a task gets stuck in
> > balance_dirty_pages_ratelimited() when perform I/O stress testing.
> > The reason we observed is that an I_DIRTY_PAGES inode with lots
> > of dirty pages is in b_dirty_time list and standard background
> > writeback cannot writeback the inode.
> > After studing the relevant code, the following scenario may lead
> > to the issue:
> >
> > task1 task2
> > ----- -----
> > fuse_flush
> > write_inode_now //in b_dirty_time
> > writeback_single_inode
> > __writeback_single_inode
> > fuse_write_end
> > filemap_dirty_folio
> > __xa_set_mark:PAGECACHE_TAG_DIRTY
> > lock inode->i_lock
> > if mapping tagged PAGECACHE_TAG_DIRTY
> > inode->i_state |= I_DIRTY_PAGES
> > unlock inode->i_lock
> > __mark_inode_dirty:I_DIRTY_PAGES
> > lock inode->i_lock
> > -was dirty,inode stays in
> > -b_dirty_time
> > unlock inode->i_lock
> >
> > if(!(inode->i_state & I_DIRTY_All))
> > -not true,so nothing done
> >
> > This patch moves the dirty inode to b_dirty list when the inode
> > currently is not queued in b_io or b_more_io list at the end of
> > writeback_single_inode.
> >
> > Signed-off-by: Jing Xia <jing.xia@xxxxxxxxxx>
>
> Thanks for report and the fix! The patch looks good so feel free to add:
>
> Reviewed-by: Jan Kara <jack@xxxxxxx>
>
> Also please add tags:
>
> CC: stable@xxxxxxxxxxxxxxx
> Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option")
>
> Thanks.
> Honza
>
> > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > index 591fe9cf1659..d7763feaf14a 100644
> > --- a/fs/fs-writeback.c
> > +++ b/fs/fs-writeback.c
> > @@ -1712,6 +1712,9 @@ static int writeback_single_inode(struct inode *inode,
> > */
> > if (!(inode->i_state & I_DIRTY_ALL))
> > inode_cgwb_move_to_attached(inode, wb);
> > + else if (!(inode->i_state & I_SYNC_QUEUED) && (inode->i_state & I_DIRTY))
> > + redirty_tail_locked(inode, wb);
> > +
> > spin_unlock(&wb->list_lock);
> > inode_sync_complete(inode);
> > out:
> > --
> > 2.17.1
> >
> --
> Jan Kara <jack@xxxxxxxx>
> SUSE Labs, CR
