Commit 224c1c70 authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

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: default avatarLiam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: default avatarLorenzo 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 63fc66f5

mm/mmap.c

+4 −11
Original line number Diff line number Diff line
@@ -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

	 */

mm/vma.c

+0 −21
Original line number Diff line number Diff line
@@ -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)

mm/vma.h

+0 −3
Original line number Diff line number Diff line
@@ -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)

{