Commit 53bee98d authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

mm: remove re-walk from mmap_region() 

Using vma_iter_set() will reset the tree and cause a re-walk.  Use
vmi_iter_config() to set the write to a sub-set of the range.  Change
the file case to also use vmi_iter_config() so that the end is correctly
set.

Link: https://lkml.kernel.org/r/20230724183157.3939892-7-Liam.Howlett@oracle.com


Signed-off-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c1297987

mm/internal.h

+8 −0
Original line number Diff line number Diff line
@@ -1041,6 +1041,14 @@ static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma) 
	return !(vma->vm_flags & VM_SOFTDIRTY);

}



static inline void vma_iter_config(struct vma_iterator *vmi,

		unsigned long index, unsigned long last)

{

	MAS_BUG_ON(&vmi->mas, vmi->mas.node != MAS_START &&

		   (vmi->mas.index > index || vmi->mas.last < index));

	__mas_set_range(&vmi->mas, index, last - 1);

}



/*

 * VMA Iterator functions shared between nommu and mmap

 */

mm/mmap.c

+10 −5
Original line number Diff line number Diff line
@@ -2676,8 +2676,11 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 


	next = vma_next(&vmi);

	prev = vma_prev(&vmi);

	if (vm_flags & VM_SPECIAL)

	if (vm_flags & VM_SPECIAL) {

		if (prev)

			vma_iter_next_range(&vmi);

		goto cannot_expand;

	}



	/* Attempt to expand an old mapping */

	/* Check next */
@@ -2698,6 +2701,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
		merge_start = prev->vm_start;

		vma = prev;

		vm_pgoff = prev->vm_pgoff;

	} else if (prev) {

		vma_iter_next_range(&vmi);

	}
@@ -2708,9 +2713,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
		goto expanded;

	}



	if (vma == prev)

		vma_iter_set(&vmi, addr);

cannot_expand:

	if (prev)

		vma_iter_next_range(&vmi);



	/*

	 * Determine the object being mapped and call the appropriate
@@ -2723,7 +2728,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
		goto unacct_error;

	}



	vma_iter_set(&vmi, addr);

	vma_iter_config(&vmi, addr, end);

	vma->vm_start = addr;

	vma->vm_end = end;

	vm_flags_init(vma, vm_flags);
@@ -2750,7 +2755,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
		if (WARN_ON((addr != vma->vm_start)))

			goto close_and_free_vma;



		vma_iter_set(&vmi, addr);

		vma_iter_config(&vmi, addr, end);

		/*

		 * If vm_flags changed after call_mmap(), we should try merge

		 * vma again as we may succeed this time.