mm: move may_expand_vm() check in mmap_region()

The may_expand_vm() check requires the count of the pages within the
munmap range.  Since this is needed for accounting and obtained later, the
reodering of ma_expand_vm() to later in the call stack, after the vma
munmap struct (vms) is initialised and the gather stage is potentially
run, will allow for a single loop over the vmas.  The gather sage does not
commit any work and so everything can be undone in the case of a failure.

The MAP_FIXED page count is available after the vms_gather_munmap_vmas()
call, so use it instead of looping over the vmas twice.

Link: https://lkml.kernel.org/r/20240830040101.822209-20-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Bert Karwatzki <spasswolf@web.de>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 0 insertions, 3 deletions

diff --git a/mm/vma.h b/mm/vma.h
index b59d470cc223..45fbc56bc0b0 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -319,9 +319,6 @@ bool vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot);
 
 int mm_take_all_locks(struct mm_struct *mm);
 void mm_drop_all_locks(struct mm_struct *mm);
-unsigned long count_vma_pages_range(struct mm_struct *mm,
-				    unsigned long addr, unsigned long end,
-				    unsigned long *nr_accounted);
 
 static inline bool vma_wants_manual_pte_write_upgrade(struct vm_area_struct *vma)
 {