mm: consistently use current->mm in mm_get_unmapped_area()

mm_get_unmapped_area() is a wrapper around arch_get_unmapped_area() /
arch_get_unmapped_area_topdown(), both of which search current->mm for
some free space.  Neither take an mm_struct - they implicitly operate on
current->mm.

But the wrapper takes an mm_struct and uses it to decide whether to search
bottom up or top down.  All callers pass in current->mm for this, so
everything is working consistently.  But it feels like an accident waiting
to happen; eventually someone will call that function with a different mm,
expecting to find free space in it, but what gets returned is free space
in the current mm.

So let's simplify by removing the parameter and have the wrapper use
current->mm to decide which end to start at.  Now everything is consistent
and self-documenting.

Link: https://lkml.kernel.org/r/20251003155306.2147572-1-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

14 files changed, 29 insertions, 37 deletions

diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 55faf2effa46..dbf118b40601 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -241,7 +241,7 @@ unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, u
 
 	if (flags & MAP_FIXED) {
 		/* Ok, don't mess with it. */
-		return mm_get_unmapped_area(current->mm, NULL, orig_addr, len, pgoff, flags);
+		return mm_get_unmapped_area(NULL, orig_addr, len, pgoff, flags);
 	}
 	flags &= ~MAP_SHARED;
 
@@ -254,7 +254,7 @@ unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, u
 		align_goal = (64UL * 1024);
 
 	do {
-		addr = mm_get_unmapped_area(current->mm, NULL, orig_addr,
+		addr = mm_get_unmapped_area(NULL, orig_addr,
 					    len + (align_goal - PAGE_SIZE), pgoff, flags);
 		if (!(addr & ~PAGE_MASK)) {
 			addr = (addr + (align_goal - 1UL)) & ~(align_goal - 1UL);
@@ -273,7 +273,7 @@ unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, u
 	 * be obtained.
 	 */
 	if (addr & ~PAGE_MASK)
-		addr = mm_get_unmapped_area(current->mm, NULL, orig_addr, len, pgoff, flags);
+		addr = mm_get_unmapped_area(NULL, orig_addr, len, pgoff, flags);
 
 	return addr;
 }
diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
index 7f8d1e11dbee..3b3efadb8cae 100644
--- a/arch/x86/kernel/cpu/sgx/driver.c
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -113,7 +113,7 @@ static unsigned long sgx_get_unmapped_area(struct file *file,
 	if (flags & MAP_FIXED)
 		return addr;
 
-	return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(file, addr, len, pgoff, flags);
 }
 
 #ifdef CONFIG_COMPAT
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 34b815901b20..db1ca53a6d01 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -542,7 +542,7 @@ static unsigned long get_unmapped_area_zero(struct file *file,
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	return thp_get_unmapped_area(file, addr, len, pgoff, flags);
 #else
-	return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(file, addr, len, pgoff, flags);
 #endif
 }
 #endif /* CONFIG_MMU */
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 2bb40a6060af..7f1ed0db8337 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -330,14 +330,13 @@ static unsigned long dax_get_unmapped_area(struct file *filp,
 	if ((off + len_align) < off)
 		goto out;
 
-	addr_align = mm_get_unmapped_area(current->mm, filp, addr, len_align,
-					  pgoff, flags);
+	addr_align = mm_get_unmapped_area(filp, addr, len_align, pgoff, flags);
 	if (!IS_ERR_VALUE(addr_align)) {
 		addr_align += (off - addr_align) & (align - 1);
 		return addr_align;
 	}
  out:
-	return mm_get_unmapped_area(current->mm, filp, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(filp, addr, len, pgoff, flags);
 }
 
 static const struct address_space_operations dev_dax_aops = {
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index f42548ee9083..ce8e40d35032 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -184,8 +184,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 	if (addr)
 		addr0 = ALIGN(addr, huge_page_size(h));
 
-	return mm_get_unmapped_area_vmflags(current->mm, file, addr0, len, pgoff,
-					    flags, 0);
+	return mm_get_unmapped_area_vmflags(file, addr0, len, pgoff, flags, 0);
 }
 
 /*
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index d9b7ef122343..2d3425cfa94b 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -443,7 +443,7 @@ pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned lo
 		return pde->proc_ops->proc_get_unmapped_area(file, orig_addr, len, pgoff, flags);
 
 #ifdef CONFIG_MMU
-	return mm_get_unmapped_area(current->mm, file, orig_addr, len, pgoff, flags);
+	return mm_get_unmapped_area(file, orig_addr, len, pgoff, flags);
 #endif
 
 	return orig_addr;
diff --git a/fs/ramfs/file-mmu.c b/fs/ramfs/file-mmu.c
index b11f5b20b78b..c3ed1c5117b2 100644
--- a/fs/ramfs/file-mmu.c
+++ b/fs/ramfs/file-mmu.c
@@ -35,7 +35,7 @@ static unsigned long ramfs_mmu_get_unmapped_area(struct file *file,
 		unsigned long addr, unsigned long len, unsigned long pgoff,
 		unsigned long flags)
 {
-	return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(file, addr, len, pgoff, flags);
 }
 
 const struct file_operations ramfs_file_operations = {
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index a74582aed747..0e1d73955fa5 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -189,12 +189,11 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 			       unsigned long len, unsigned long pgoff,
 			       unsigned long flags, vm_flags_t);
 
-unsigned long mm_get_unmapped_area(struct mm_struct *mm, struct file *filp,
-				   unsigned long addr, unsigned long len,
-				   unsigned long pgoff, unsigned long flags);
+unsigned long mm_get_unmapped_area(struct file *filp, unsigned long addr,
+				   unsigned long len, unsigned long pgoff,
+				   unsigned long flags);
 
-unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm,
-					   struct file *filp,
+unsigned long mm_get_unmapped_area_vmflags(struct file *filp,
 					   unsigned long addr,
 					   unsigned long len,
 					   unsigned long pgoff,
diff --git a/io_uring/memmap.c b/io_uring/memmap.c
index add03ca75cb9..63fcfa757bb8 100644
--- a/io_uring/memmap.c
+++ b/io_uring/memmap.c
@@ -387,7 +387,7 @@ unsigned long io_uring_get_unmapped_area(struct file *filp, unsigned long addr,
 #else
 	addr = 0UL;
 #endif
-	return mm_get_unmapped_area(current->mm, filp, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(filp, addr, len, pgoff, flags);
 }
 
 #else /* !CONFIG_MMU */
diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
index 1074ac4459f2..872dc0e41c65 100644
--- a/kernel/bpf/arena.c
+++ b/kernel/bpf/arena.c
@@ -334,7 +334,7 @@ static unsigned long arena_get_unmapped_area(struct file *filp, unsigned long ad
 			return -EINVAL;
 	}
 
-	ret = mm_get_unmapped_area(current->mm, filp, addr, len * 2, 0, flags);
+	ret = mm_get_unmapped_area(filp, addr, len * 2, 0, flags);
 	if (IS_ERR_VALUE(ret))
 		return ret;
 	if ((ret >> 32) == ((ret + len - 1) >> 32))
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 8a129746bd6c..d77685f2c6cb 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1162,7 +1162,7 @@ static unsigned long bpf_get_unmapped_area(struct file *filp, unsigned long addr
 	if (map->ops->map_get_unmapped_area)
 		return map->ops->map_get_unmapped_area(filp, addr, len, pgoff, flags);
 #ifdef CONFIG_MMU
-	return mm_get_unmapped_area(current->mm, filp, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(filp, addr, len, pgoff, flags);
 #else
 	return addr;
 #endif
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2f2a521e5d68..32479ae27400 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1127,7 +1127,7 @@ static unsigned long __thp_get_unmapped_area(struct file *filp,
 	if (len_pad < len || (off + len_pad) < off)
 		return 0;
 
-	ret = mm_get_unmapped_area_vmflags(current->mm, filp, addr, len_pad,
+	ret = mm_get_unmapped_area_vmflags(filp, addr, len_pad,
 					   off >> PAGE_SHIFT, flags, vm_flags);
 
 	/*
@@ -1164,7 +1164,7 @@ unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long add
 	if (ret)
 		return ret;
 
-	return mm_get_unmapped_area_vmflags(current->mm, filp, addr, len, pgoff, flags,
+	return mm_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags,
 					    vm_flags);
 }
 
diff --git a/mm/mmap.c b/mm/mmap.c
index 5fd3b80fda1d..644f02071a41 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -797,12 +797,11 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 }
 #endif
 
-unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm, struct file *filp,
-					   unsigned long addr, unsigned long len,
-					   unsigned long pgoff, unsigned long flags,
-					   vm_flags_t vm_flags)
+unsigned long mm_get_unmapped_area_vmflags(struct file *filp, unsigned long addr,
+					   unsigned long len, unsigned long pgoff,
+					   unsigned long flags, vm_flags_t vm_flags)
 {
-	if (mm_flags_test(MMF_TOPDOWN, mm))
+	if (mm_flags_test(MMF_TOPDOWN, current->mm))
 		return arch_get_unmapped_area_topdown(filp, addr, len, pgoff,
 						      flags, vm_flags);
 	return arch_get_unmapped_area(filp, addr, len, pgoff, flags, vm_flags);
@@ -848,7 +847,7 @@ __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 		addr = thp_get_unmapped_area_vmflags(file, addr, len,
 						     pgoff, flags, vm_flags);
 	} else {
-		addr = mm_get_unmapped_area_vmflags(current->mm, file, addr, len,
+		addr = mm_get_unmapped_area_vmflags(file, addr, len,
 						    pgoff, flags, vm_flags);
 	}
 	if (IS_ERR_VALUE(addr))
@@ -864,12 +863,10 @@ __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 }
 
 unsigned long
-mm_get_unmapped_area(struct mm_struct *mm, struct file *file,
-		     unsigned long addr, unsigned long len,
+mm_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 		     unsigned long pgoff, unsigned long flags)
 {
-	return mm_get_unmapped_area_vmflags(mm, file, addr, len,
-					    pgoff, flags, 0);
+	return mm_get_unmapped_area_vmflags(file, addr, len, pgoff, flags, 0);
 }
 EXPORT_SYMBOL(mm_get_unmapped_area);
 
diff --git a/mm/shmem.c b/mm/shmem.c
index 58701d14dd96..0eecb486a0cb 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2759,8 +2759,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
-	addr = mm_get_unmapped_area(current->mm, file, uaddr, len, pgoff,
-				    flags);
+	addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
 
 	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
 		return addr;
@@ -2838,8 +2837,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 	if (inflated_len < len)
 		return addr;
 
-	inflated_addr = mm_get_unmapped_area(current->mm, NULL, uaddr,
-					     inflated_len, 0, flags);
+	inflated_addr = mm_get_unmapped_area(NULL, uaddr, inflated_len, 0, flags);
 	if (IS_ERR_VALUE(inflated_addr))
 		return addr;
 	if (inflated_addr & ~PAGE_MASK)
@@ -5775,7 +5773,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 				      unsigned long addr, unsigned long len,
 				      unsigned long pgoff, unsigned long flags)
 {
-	return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(file, addr, len, pgoff, flags);
 }
 #endif