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mm: move may_expand_vm() check in mmap_region()

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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>
This commit is contained in:
Liam R. Howlett 2024-08-30 00:00:59 -04:00 • committed by Andrew Morton
parent 63fc66f5b6
commit 224c1c702c
3 changed files with 4 additions and 35 deletions
Download patch file Download diff file Expand all files Collapse all files

15
mm/mmap.c
View file

@ -1376,17 +1376,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
pgoff_t vm_pgoff;
int error = -ENOMEM;
VMA_ITERATOR(vmi, mm, addr);
unsigned long nr_pages, nr_accounted;
nr_pages = count_vma_pages_range(mm, addr, end, &nr_accounted);
/*
* Check against address space limit.
* MAP_FIXED may remove pages of mappings that intersects with requested
* mapping. Account for the pages it would unmap.
*/
if (!may_expand_vm(mm, vm_flags, pglen - nr_pages))
return -ENOMEM;
/* Find the first overlapping VMA */
vma = vma_find(&vmi, end);
@ -1410,6 +1399,10 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
vma_iter_next_range(&vmi);
}
/* Check against address space limit. */
if (!may_expand_vm(mm, vm_flags, pglen - vms.nr_pages))
goto abort_munmap;
/*
* Private writable mapping: check memory availability
*/

21
mm/vma.c
View file

@ -1640,27 +1640,6 @@ bool vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
return vma_fs_can_writeback(vma);
}
unsigned long count_vma_pages_range(struct mm_struct *mm,
unsigned long addr, unsigned long end,
unsigned long *nr_accounted)
{
VMA_ITERATOR(vmi, mm, addr);
struct vm_area_struct *vma;
unsigned long nr_pages = 0;
*nr_accounted = 0;
for_each_vma_range(vmi, vma, end) {
unsigned long vm_start = max(addr, vma->vm_start);
unsigned long vm_end = min(end, vma->vm_end);
nr_pages += PHYS_PFN(vm_end - vm_start);
if (vma->vm_flags & VM_ACCOUNT)
*nr_accounted += PHYS_PFN(vm_end - vm_start);
}
return nr_pages;
}
static DEFINE_MUTEX(mm_all_locks_mutex);
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)

3
mm/vma.h
View file

@ -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)
{