[PATCH 0/5] mm: Switch gfp_t to unsigned long

[Brendan Jackman <jackmanb@google.com>]

As pointed out by Vlastimil in [0], my proposal for __GFP_UNMAPPED is
probably not needed for 32-bit. This offers a way out of the GFP flag
scarcity so in preparation for this, flip gfp_t to be 64-bit on 64-bit
machines, while leaving it 32-bit on 32-bit machines.

For mm-internal code that prints raw GFP flags as hex, this just updates
the format specifier to %lx. Presumably developers have a reason for
wanting to see the whole flags word as a number in the log. For printks
outside of mm/, I assume they are only using %x because the authors
didn't know about %pGg, so they are converted to the latter as prep
patches.

Stuff I've done to try and find issues with this:

- Built x86 allmodconfig and arm64 defconfig. Hopefully the 0-day bot
  will alert me to the important builds I'm missing (I briefly tried to
  build s390 and sparc64 but ran into tooling issues and gave up).

- Ran some selftests on a x86 VM.

- Poked around at stuff that refers to ___GFP_LAST_BIT to see if
  anything looks wrong.

- Ran this Coccinelle script to look for explicit casts to plain int:

---
virtual report

@r@
gfp_t x;
position p;
@@

(
  (unsigned int)x@p
|
  (int)x@p
)

@script:python depends on report@
p << r.p;
@@
msg = "WARNING: Explicit integer cast of gfp_t"
coccilib.report.print_report(p[0], msg)
---

Obviously this series doesn't "do anything" so maybe it doesn't make
sense to merge it unless it goes in alongside __GFP_UNMAPPED, but it
does seem to make sense to review it independently so I'm posting it as
a separate series.

[0] https://lore.kernel.org/all/6206d021-e6c2-4899-b426-cacd71ebd5ef@kernel.org/

To: Andrew Morton <akpm@linux-foundation.org>
To: Michal Hocko <mhocko@suse.com>
To: David Rientjes <rientjes@google.com>
To: Shakeel Butt <shakeel.butt@linux.dev>
To: Vlastimil Babka <vbabka@kernel.org>
To: Suren Baghdasaryan <surenb@google.com>
To: Brendan Jackman <jackmanb@google.com>
To: Johannes Weiner <hannes@cmpxchg.org>
To: Zi Yan <ziy@nvidia.com>
To: Harry Yoo <harry.yoo@oracle.com>
To: Hao Li <hao.li@linux.dev>
To: Christoph Lameter <cl@gentwo.org>
To: Roman Gushchin <roman.gushchin@linux.dev>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org

Signed-off-by: Brendan Jackman <jackmanb@google.com>

---
Brendan Jackman (5):
      drm/managed: Use special gfp_t format specifier
      iwlegacy: 3945-mac: Use special gfp_t format specifier
      mm/kfence: Use special gfp_t format specifier
      net/rds: Use special gfp_t format specifier
      mm: Change gfp_t to unsigned long

 drivers/gpu/drm/drm_managed.c                  | 4 ++--
 drivers/net/wireless/intel/iwlegacy/3945-mac.c | 4 ++--
 include/linux/types.h                          | 2 +-
 lib/test_lockup.c                              | 2 +-
 mm/kfence/kfence_test.c                        | 2 +-
 mm/oom_kill.c                                  | 2 +-
 mm/page_alloc.c                                | 5 ++++-
 mm/page_owner.c                                | 4 ++--
 mm/slab_common.c                               | 2 +-
 mm/slub.c                                      | 2 +-
 mm/vmalloc.c                                   | 2 +-
 net/rds/tcp_recv.c                             | 2 +-
 12 files changed, 18 insertions(+), 15 deletions(-)
---
base-commit: 8a30aeb0d1b4e4aaf7f7bae72f20f2ae75385ccb
change-id: 20260319-gfp64-7a970a80ba4e

Best regards,
-- 
Brendan Jackman <jackmanb@google.com>