Re: buffer cache simplification v4

[Christoph Hellwig <hch@lst.de>]

On Tue, Mar 17, 2026 at 08:13:04AM -0400, Brian Foster wrote:
> On Mon, Mar 16, 2026 at 04:41:32PM +0100, Christoph Hellwig wrote:
> > Hi all,
> > 
> > this series has a few old patches that simplify the LRU handling, and
> > moves back to only having a per-buftarg hash now that the buffer hash
> > is using the scalable rhashtable.  While some of this looks like
> > performance work, performance and scalability is unchanged even on the
> > 80 core dual socket system I test this on.  Besides cleaning up the
> > code nice, it also happens to fix a syzcaller reported use after free
> > during buffer shutdown, which happened incidentally because of how the
> > tear down of the buftarg vs the perag structures is handled.
> > 
> > Changes since v3:
> >  - split the change to handling how referenced buffers on the LRU
> >    are handled into a separate patch
> > 
> 
> It looks like there's a patch ordering problem or something here. It
> doesn't apply to master, and looks like patch 1 is trying to modify
> hunks that don't yet exist. A local rebase issue related to reordering
> the change in patch 3 perhaps..?

This is against the xfs for-next tree (commit
f8544b654f22b1138ba12bc0971a96963b20311d)