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mm: remove re-walk from mmap_region()

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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: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2023-07-24 14:31:48 -04:00 committed by Andrew Morton
parent c1297987cc
commit 53bee98d00
2 changed files with 18 additions and 5 deletions
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8
mm/internal.h
View file

@ -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
*/

15
mm/mmap.c
View file

@ -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.