Re: Known and unfixed active data loss bug in MM + XFS with large folios since Dec 2021 (any kernel from 6.1 upwards)

[Dave Chinner]

On Wed, Sep 18, 2024 at 02:34:57PM +0100, Matthew Wilcox wrote:
> On Wed, Sep 18, 2024 at 11:28:52AM +0200, Chris Mason wrote:
> > I think the bug was in __filemap_add_folio()'s usage of xarray_split_alloc()
> > and the tree changing before taking the lock.  It's just a guess, but that
> > was always my biggest suspect.
> 
> Oh god, that's it.
> 
> there should have been an xas_reset() after calling xas_split_alloc().
> 
> and 6758c1128ceb calls xas_reset() after calling xas_split_alloc().

Should we be asking for 6758c1128ceb to be backported to all
stable kernels then?

-Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx