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UPSTREAM: mm: Fix TLB flush for not-first PFNMAP mappings in unmap_region()

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This is a stable-specific patch.
I botched the stable-specific rewrite of
commit b67fbebd4c ("mmu_gather: Force tlb-flush VM_PFNMAP vmas"):
As Hugh pointed out, unmap_region() actually operates on a list of VMAs,
and the variable "vma" merely points to the first VMA in that list.
So if we want to check whether any of the VMAs we're operating on is
PFNMAP or MIXEDMAP, we have to iterate through the list and check each VMA.

Bug: 245812080
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 3998dc50eb)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I115183f65fc7df5d33264e6211adcd2ec531d996
This commit is contained in:
Jann Horn
2022-09-15 16:25:19 +02:00
committed by Lee Jones
parent 75c194cf1a
commit c0ce22abf7
1 changed files with 7 additions and 2 deletions
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9
mm/mmap.c
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@@ -2768,6 +2768,7 @@ static void unmap_region(struct mm_struct *mm,
{
struct vm_area_struct *next = vma_next(mm, prev);
struct mmu_gather tlb;
struct vm_area_struct *cur_vma;
lru_add_drain();
tlb_gather_mmu(&tlb, mm, start, end);
@@ -2782,8 +2783,12 @@ static void unmap_region(struct mm_struct *mm,
* concurrent flush in this region has to be coming through the rmap,
* and we synchronize against that using the rmap lock.
*/
if ((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) != 0)
tlb_flush_mmu(&tlb);
for (cur_vma = vma; cur_vma; cur_vma = cur_vma->vm_next) {
if ((cur_vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) != 0) {
tlb_flush_mmu(&tlb);
break;
}
}
free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
next ? next->vm_start : USER_PGTABLES_CEILING);