Re: [PATCH 22/25] fs/buffer: prevent WARN_ON in __alloc_pages_slowpath() when BS > PS

[Darrick J. Wong]

On Sat, Oct 25, 2025 at 05:45:29AM +0100, Matthew Wilcox wrote:
> On Sat, Oct 25, 2025 at 11:22:18AM +0800, libaokun@xxxxxxxxxxxxxxx wrote:
> > +	while (1) {
> > +		folio = __filemap_get_folio(mapping, index, fgp_flags,
> > +					    gfp & ~__GFP_NOFAIL);
> > +		if (!IS_ERR(folio) || !(gfp & __GFP_NOFAIL))
> > +			return folio;
> > +
> > +		if (PTR_ERR(folio) != -ENOMEM && PTR_ERR(folio) != -EAGAIN)
> > +			return folio;
> > +
> > +		memalloc_retry_wait(gfp);
> > +	}
> 
> No, absolutely not.  We're not having open-coded GFP_NOFAIL semantics.
> The right way forward is for ext4 to use iomap, not for buffer heads
> to support large block sizes.

Seconded.

--D