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| author | Ryan Roberts <ryan.roberts@arm.com> | 2025-10-03 18:53:04 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-11-17 04:27:57 +0300 |
| commit | 9ac09bb9feaccc2f45e5606dc48a3f748d478dc4 (patch) | |
| tree | 112b8ef9515691a047d5db1356ad064c38d91117 /drivers | |
| parent | 0fdaa13ee93a068251d32ea7f60fd439b445adbe (diff) | |
| download | linux-9ac09bb9feaccc2f45e5606dc48a3f748d478dc4.tar.xz | |
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/char/mem.c | 2 | ||||
| -rw-r--r-- | drivers/dax/device.c | 5 |
2 files changed, 3 insertions, 4 deletions
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 = { |