[PATCH 5/5] mm: Change gfp_t to unsigned long
From: Brendan Jackman
Date: Thu Mar 19 2026 - 12:19:18 EST
GFP flag bits are starting to get scarce. There are upcoming features
that can tolerate being 64-bit only, which offers a simple way to escape
GFP bit scarcity: just make gfp_t 64 bits on 64 bit systems.
Update mm-internal printk formats to use %lx - external format strings
have already been decoupled from the size of gfp_t. Also
lib/test_lockup.c which uses the arg in a module_param_unsafe()
invocation where gfp_t doesn't work.
Some care needs to be taken here with code that converts between ALLOC_*
flags and GFP flags since the former are still unsigned int. The current
code is fine but just to be safe, add a BUILD_BUG_ON() for each GFP
flag that gets converted this way.
Signed-off-by: Brendan Jackman <jackmanb@xxxxxxxxxx>
---
include/linux/types.h | 2 +-
lib/test_lockup.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 +-
8 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/include/linux/types.h b/include/linux/types.h
index 7e71d260763c7..a8490c1381f99 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -160,7 +160,7 @@ typedef u64 dma_addr_t;
typedef u32 dma_addr_t;
#endif
-typedef unsigned int __bitwise gfp_t;
+typedef unsigned long __bitwise gfp_t;
typedef unsigned int __bitwise slab_flags_t;
typedef unsigned int __bitwise fmode_t;
diff --git a/lib/test_lockup.c b/lib/test_lockup.c
index c3fd87d6c2dd0..7adc03ac0b39d 100644
--- a/lib/test_lockup.c
+++ b/lib/test_lockup.c
@@ -130,7 +130,7 @@ module_param(alloc_pages_order, uint, 0400);
MODULE_PARM_DESC(alloc_pages_order, "page order to allocate");
static gfp_t alloc_pages_gfp = GFP_KERNEL;
-module_param_unsafe(alloc_pages_gfp, uint, 0400);
+module_param_unsafe(alloc_pages_gfp, unsigned long, 0400);
MODULE_PARM_DESC(alloc_pages_gfp, "allocate pages with this gfp_mask, default GFP_KERNEL");
static bool alloc_pages_atomic;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 5c6c95c169ee8..272ecce090f75 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -458,7 +458,7 @@ static void dump_oom_victim(struct oom_control *oc, struct task_struct *victim)
static void dump_header(struct oom_control *oc)
{
- pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), order=%d, oom_score_adj=%d\n",
+ pr_warn("%s invoked oom-killer: gfp_mask=%#lx(%pGg), order=%d, oom_score_adj=%d\n",
current->comm, oc->gfp_mask, &oc->gfp_mask, oc->order,
current->signal->oom_score_adj);
if (!IS_ENABLED(CONFIG_COMPACTION) && oc->order)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2d4b6f1a554ed..f0b9e8a950ee7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4036,7 +4036,7 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
- pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl",
+ pr_warn("%s: %pV, mode:%#lx(%pGg), nodemask=%*pbl",
current->comm, &vaf, gfp_mask, &gfp_mask,
nodemask_pr_args(nodemask));
va_end(args);
@@ -4504,6 +4504,9 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order)
*/
BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_MIN_RESERVE);
BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD);
+ /* Alloc flags are unsigned int, gfp_t may be larger. */
+ BUILD_BUG_ON(___GFP_HIGH_BIT >= BITS_PER_TYPE(typeof(alloc_flags)));
+ BUILD_BUG_ON(___GFP_KSWAPD_RECLAIM_BIT >= BITS_PER_TYPE(typeof(alloc_flags)));
/*
* The caller may dip into page reserves a bit more if the caller
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 8178e0be557f8..70afbdb945b1e 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -558,7 +558,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
return -ENOMEM;
ret = scnprintf(kbuf, count,
- "Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns\n",
+ "Page allocated via order %u, mask %#lx(%pGg), pid %d, tgid %d (%s), ts %llu ns\n",
page_owner->order, page_owner->gfp_mask,
&page_owner->gfp_mask, page_owner->pid,
page_owner->tgid, page_owner->comm,
@@ -630,7 +630,7 @@ void __dump_page_owner(const struct page *page)
else
pr_alert("page_owner tracks the page as freed\n");
- pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu, free_ts %llu\n",
+ pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#lx(%pGg), pid %d, tgid %d (%s), ts %llu, free_ts %llu\n",
page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
page_owner->pid, page_owner->tgid, page_owner->comm,
page_owner->ts_nsec, page_owner->free_ts_nsec);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index d5a70a831a2a5..548e0d0f9aab3 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1028,7 +1028,7 @@ gfp_t kmalloc_fix_flags(gfp_t flags)
gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
flags &= ~GFP_SLAB_BUG_MASK;
- pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
+ pr_warn("Unexpected gfp: %#lx (%pGg). Fixing up to gfp: %#lx (%pGg). Fix your code!\n",
invalid_mask, &invalid_mask, flags, &flags);
dump_stack();
diff --git a/mm/slub.c b/mm/slub.c
index 2b2d33cc735cb..083f4e9de3ecb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4235,7 +4235,7 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
return;
- pr_warn("SLUB: Unable to allocate memory on CPU %u (of node %d) on node %d, gfp=%#x(%pGg)\n",
+ pr_warn("SLUB: Unable to allocate memory on CPU %u (of node %d) on node %d, gfp=%#lx(%pGg)\n",
cpu, cpu_to_node(cpu), nid, gfpflags, &gfpflags);
pr_warn(" cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n",
s->name, s->object_size, s->size, oo_order(s->oo),
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 61caa55a44027..e353e281fa95d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3949,7 +3949,7 @@ static gfp_t vmalloc_fix_flags(gfp_t flags)
gfp_t invalid_mask = flags & ~GFP_VMALLOC_SUPPORTED;
flags &= GFP_VMALLOC_SUPPORTED;
- WARN_ONCE(1, "Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
+ WARN_ONCE(1, "Unexpected gfp: %#lx (%pGg). Fixing up to gfp: %#lx (%pGg). Fix your code!\n",
invalid_mask, &invalid_mask, flags, &flags);
return flags;
}
--
2.51.2