Commit fc21959f authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Andrew Morton
Browse files

mm: abstract vma_expand() to use vma_merge_struct 

The purpose of the vmg is to thread merge state through functions and
avoid egregious parameter lists.  We expand this to vma_expand(), which is
used for a number of merge cases.

Accordingly, adjust its callers, mmap_region() and relocate_vma_down(), to
use a vmg.

An added purpose of this change is the ability in a future commit to
perform all new VMA range merging using vma_expand().

Link: https://lkml.kernel.org/r/4bc8c9dbc9ca52452ef8e587b28fe555854ceb38.1725040657.git.lorenzo.stoakes@oracle.com


Signed-off-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
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: 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>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3e01310d

mm/mmap.c

+8 −7
Original line number Diff line number Diff line
@@ -1371,7 +1371,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
	struct ma_state mas_detach;

	struct maple_tree mt_detach;

	unsigned long end = addr + len;

	unsigned long merge_start = addr, merge_end = end;

	bool writable_file_mapping = false;

	int error = -ENOMEM;

	VMA_ITERATOR(vmi, mm, addr);
@@ -1424,8 +1423,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
	/* Attempt to expand an old mapping */

	/* Check next */

	if (next && next->vm_start == end && can_vma_merge_before(&vmg)) {

		merge_end = next->vm_end;

		vma = next;

		vmg.end = next->vm_end;

		vma = vmg.vma = next;

		vmg.pgoff = next->vm_pgoff - pglen;

		/*

		 * We set this here so if we will merge with the previous VMA in
@@ -1438,15 +1437,15 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 


	/* Check prev */

	if (prev && prev->vm_end == addr && can_vma_merge_after(&vmg)) {

		merge_start = prev->vm_start;

		vma = prev;

		vmg.start = prev->vm_start;

		vma = vmg.vma = prev;

		vmg.pgoff = prev->vm_pgoff;

		vma_prev(&vmi); /* Equivalent to going to the previous range */

	}



	if (vma) {

		/* Actually expand, if possible */

		if (!vma_expand(&vmi, vma, merge_start, merge_end, vmg.pgoff, next)) {

		if (!vma_expand(&vmg)) {

			khugepaged_enter_vma(vma, vm_flags);

			goto expanded;

		}
@@ -2320,6 +2319,7 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift) 
	unsigned long new_start = old_start - shift;

	unsigned long new_end = old_end - shift;

	VMA_ITERATOR(vmi, mm, new_start);

	VMG_STATE(vmg, mm, &vmi, new_start, old_end, 0, vma->vm_pgoff);

	struct vm_area_struct *next;

	struct mmu_gather tlb;
@@ -2336,7 +2336,8 @@ int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift) 
	/*

	 * cover the whole range: [new_start, old_end)

	 */

	if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))

	vmg.vma = vma;

	if (vma_expand(&vmg))

		return -ENOMEM;



	/*

mm/vma.c

+17 −22
Original line number Diff line number Diff line
@@ -467,30 +467,25 @@ void validate_mm(struct mm_struct *mm) 
/*

 * vma_expand - Expand an existing VMA

 *

 * @vmi: The vma iterator

 * @vma: The vma to expand

 * @start: The start of the vma

 * @end: The exclusive end of the vma

 * @pgoff: The page offset of vma

 * @next: The current of next vma.

 * @vmg: Describes a VMA expansion operation.

 *

 * Expand @vma to @start and @end.  Can expand off the start and end.  Will

 * expand over @next if it's different from @vma and @end == @next->vm_end.

 * Checking if the @vma can expand and merge with @next needs to be handled by

 * the caller.

 * Expand @vma to vmg->start and vmg->end.  Can expand off the start and end.

 * Will expand over vmg->next if it's different from vmg->vma and vmg->end ==

 * vmg->next->vm_end.  Checking if the vmg->vma can expand and merge with

 * vmg->next needs to be handled by the caller.

 *

 * Returns: 0 on success

 */

int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,

	       unsigned long start, unsigned long end, pgoff_t pgoff,

	       struct vm_area_struct *next)

int vma_expand(struct vma_merge_struct *vmg)

{

	struct vm_area_struct *anon_dup = NULL;

	bool remove_next = false;

	struct vm_area_struct *vma = vmg->vma;

	struct vm_area_struct *next = vmg->next;

	struct vma_prepare vp;



	vma_start_write(vma);

	if (next && (vma != next) && (end == next->vm_end)) {

	if (next && (vma != next) && (vmg->end == next->vm_end)) {

		int ret;



		remove_next = true;
@@ -503,21 +498,21 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, 
	init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);

	/* Not merging but overwriting any part of next is not handled. */

	VM_WARN_ON(next && !vp.remove &&

		  next != vma && end > next->vm_start);

		  next != vma && vmg->end > next->vm_start);

	/* Only handles expanding */

	VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);

	VM_WARN_ON(vma->vm_start < vmg->start || vma->vm_end > vmg->end);



	/* Note: vma iterator must be pointing to 'start' */

	vma_iter_config(vmi, start, end);

	if (vma_iter_prealloc(vmi, vma))

	vma_iter_config(vmg->vmi, vmg->start, vmg->end);

	if (vma_iter_prealloc(vmg->vmi, vma))

		goto nomem;



	vma_prepare(&vp);

	vma_adjust_trans_huge(vma, start, end, 0);

	vma_set_range(vma, start, end, pgoff);

	vma_iter_store(vmi, vma);

	vma_adjust_trans_huge(vma, vmg->start, vmg->end, 0);

	vma_set_range(vma, vmg->start, vmg->end, vmg->pgoff);

	vma_iter_store(vmg->vmi, vma);



	vma_complete(&vp, vmi, vma->vm_mm);

	vma_complete(&vp, vmg->vmi, vma->vm_mm);

	return 0;



nomem:

mm/vma.h

+1 −4
Original line number Diff line number Diff line
@@ -128,10 +128,7 @@ void init_vma_prep(struct vma_prepare *vp, 
void vma_complete(struct vma_prepare *vp,

		  struct vma_iterator *vmi, struct mm_struct *mm);



int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,

	       unsigned long start, unsigned long end, pgoff_t pgoff,

	       struct vm_area_struct *next);



int vma_expand(struct vma_merge_struct *vmg);

int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,

	       unsigned long start, unsigned long end, pgoff_t pgoff);

tools/testing/vma/vma.c

+1 −2
Original line number Diff line number Diff line
@@ -121,8 +121,7 @@ static struct vm_area_struct *merge_existing(struct vma_merge_struct *vmg) 
 */

static int expand_existing(struct vma_merge_struct *vmg)

{

	return vma_expand(vmg->vmi, vmg->vma, vmg->start, vmg->end, vmg->pgoff,

			  vmg->next);

	return vma_expand(vmg);

}



/*