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

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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>
This commit is contained in:
Ryan Roberts
2025-10-03 16:53:04 +01:00
committed by Andrew Morton
parent 0fdaa13ee9
commit 9ac09bb9fe
14 changed files with 29 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/sparc/kernel/sys_sparc_64.c
View File

@@ -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;
}

2
arch/x86/kernel/cpu/sgx/driver.c
View File

@@ -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

2
drivers/char/mem.c
View File

@@ -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 */

5
drivers/dax/device.c
View File

@@ -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 = {

3
fs/hugetlbfs/inode.c
View File

@@ -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);
}
/*

2
fs/proc/inode.c
View File

@@ -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;

2
fs/ramfs/file-mmu.c
View File

@@ -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 = {

9
include/linux/sched/mm.h
View File

@@ -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,

2
io_uring/memmap.c
View File

@@ -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 */

2
kernel/bpf/arena.c
View File

@@ -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))

2
kernel/bpf/syscall.c
View File

@@ -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

4
mm/huge_memory.c
View File

@@ -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);
}

17
mm/mmap.c
View File

@@ -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);

8
mm/shmem.c
View File

@@ -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