The patch titled
nommu: remove a superfluous check of vm_region::vm_usage
has been added to the -mm tree. Its filename is
nommu-remove-a-superfluous-check-of-vm_region-vm_usage.patch
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------------------------------------------------------
Subject: nommu: remove a superfluous check of vm_region::vm_usage
From: David Howells <dhowells@xxxxxxxxxx>
In split_vma(), there's no need to check if the VMA being split has a
region that's in use by more than one VMA because:
(1) The preceding test prohibits splitting of non-anonymous VMAs and regions
(eg: file or chardev backed VMAs).
(2) Anonymous regions can't be mapped multiple times because there's no handle
by which to refer to the already existing region.
(3) If a VMA has previously been split, then the region backing it has also
been split into two regions, each of usage 1.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Greg Ungerer <gerg@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/nommu.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff -puN mm/nommu.c~nommu-remove-a-superfluous-check-of-vm_region-vm_usage mm/nommu.c
--- a/mm/nommu.c~nommu-remove-a-superfluous-check-of-vm_region-vm_usage
+++ a/mm/nommu.c
@@ -1441,10 +1441,9 @@ int split_vma(struct mm_struct *mm, stru
kenter("");
- /* we're only permitted to split anonymous regions that have a single
- * owner */
- if (vma->vm_file ||
- vma->vm_region->vm_usage != 1)
+ /* we're only permitted to split anonymous regions (these should have
+ * only a single usage on the region) */
+ if (vma->vm_file)
return -ENOMEM;
if (mm->map_count >= sysctl_max_map_count)
_
Patches currently in -mm which might be from dhowells@xxxxxxxxxx are
nommu-fix-sysv-shm-for-nommu.patch
nommu-struct-vm_regions-vm_usage-count-need-not-be-atomic.patch
nommu-remove-a-superfluous-check-of-vm_region-vm_usage.patch
nommu-dont-need-get_unmapped_area-for-nommu.patch
nommu-fix-race-between-ramfs-truncation-and-shared-mmap.patch
nommu-fix-shared-mmap-after-truncate-shrinkage-problems.patch
kernel-credc-use-kmem_cache_free.patch
nfs-avoid-warnings-when-config_nfs_v4=n.patch
frv-duplicate-output_buffer-of-e03.patch
coredump-unify-dump_seek-implementations-for-each-binfmt_c.patch
coredump-move-dump_write-and-dump_seek-into-a-header-file.patch
elf-coredump-replace-elf_core_extra_-macros-by-functions.patch
elf-coredump-make-offset-calculation-process-and-writing-process-explicit.patch
elf-coredump-add-extended-numbering-support.patch
mutex-subsystem-synchro-test-module.patch
mutex-subsystem-synchro-test-module-add-missing-header-file.patch
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