Re: [PATCH v2 0/3] mm/huge_memory: vmf_insert_folio_*() and vmf_insert_pfn_pud() fixes

[Alistair Popple <apopple@nvidia.com>]

On Wed, Jun 11, 2025 at 02:06:51PM +0200, David Hildenbrand wrote:
> This is v2 of
> 	"[PATCH v1 0/2] mm/huge_memory: don't mark refcounted pages special
> 	 in vmf_insert_folio_*()"
> Now with one additional fix, based on mm/mm-unstable.
> 
> While working on improving vm_normal_page() and friends, I stumbled
> over this issues: refcounted "normal" pages must not be marked
> using pmd_special() / pud_special().
> 
> Fortunately, so far there doesn't seem to be serious damage.
> 
> I spent too much time trying to get the ndctl tests mentioned by Dan
> running (.config tweaks, memmap= setup, ... ), without getting them to
> pass even without these patches. Some SKIP, some FAIL, some sometimes
> suddenly SKIP on first invocation, ... instructions unclear or the tests
> are shaky. This is how far I got:

FWIW I had a similar experience, although I eventually got the FAIL cases below
to pass. I forget exactly what I needed to tweak for that though :-/

> # meson test -C build --suite ndctl:dax
> ninja: Entering directory `/root/ndctl/build'
> [1/70] Generating version.h with a custom command
>  1/13 ndctl:dax / daxdev-errors.sh          OK              15.08s
>  2/13 ndctl:dax / multi-dax.sh              OK               5.80s
>  3/13 ndctl:dax / sub-section.sh            SKIP             0.39s   exit status 77
>  4/13 ndctl:dax / dax-dev                   OK               1.37s
>  5/13 ndctl:dax / dax-ext4.sh               OK              32.70s
>  6/13 ndctl:dax / dax-xfs.sh                OK              29.43s
>  7/13 ndctl:dax / device-dax                OK              44.50s
>  8/13 ndctl:dax / revoke-devmem             OK               0.98s
>  9/13 ndctl:dax / device-dax-fio.sh         SKIP             0.10s   exit status 77
> 10/13 ndctl:dax / daxctl-devices.sh         SKIP             0.16s   exit status 77
> 11/13 ndctl:dax / daxctl-create.sh          FAIL             2.61s   exit status 1
> 12/13 ndctl:dax / dm.sh                     FAIL             0.23s   exit status 1
> 13/13 ndctl:dax / mmap.sh                   OK             437.86s
> 
> So, no idea if this series breaks something, because the tests are rather
> unreliable. I have plenty of other debug settings on, maybe that's a
> problem? I guess if the FS tests and mmap test pass, we're mostly good.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Alistair Popple <apopple@nvidia.com>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Suren Baghdasaryan <surenb@google.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Nico Pache <npache@redhat.com>
> Cc: Ryan Roberts <ryan.roberts@arm.com>
> Cc: Dev Jain <dev.jain@arm.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> 
> 
> v1 -> v2:
> * "mm/huge_memory: don't ignore queried cachemode in vmf_insert_pfn_pud()"
>  -> Added after stumbling over that
> * Modified the other tests to reuse the existing function by passing a
>   new struct
> * Renamed the patches to talk about "folios" instead of pages and adjusted
>   the patch descriptions
> * Dropped RB/TB from Dan and Oscar due to the changes
> 
> David Hildenbrand (3):
>   mm/huge_memory: don't ignore queried cachemode in vmf_insert_pfn_pud()
>   mm/huge_memory: don't mark refcounted folios special in
>     vmf_insert_folio_pmd()
>   mm/huge_memory: don't mark refcounted folios special in
>     vmf_insert_folio_pud()
> 
>  include/linux/mm.h |  19 +++++++-
>  mm/huge_memory.c   | 110 +++++++++++++++++++++++++++------------------
>  2 files changed, 85 insertions(+), 44 deletions(-)
> 
> -- 
> 2.49.0
>