From: Jason Gunthorpe <j...@mellanox.com>
The checking boils down to some racy check if the pagemap is still
available or not. Instead of checking this, rely entirely on the
notifiers, if a pagemap is destroyed then all pages that belong to it must
be removed from the tables and the notifiers triggered.
Reviewed-by: Ralph Campbell <rcampb...@nvidia.com>
Reviewed-by: Christoph Hellwig <h...@lst.de>
Signed-off-by: Jason Gunthorpe <j...@mellanox.com>
---
mm/hmm.c | 50 ++------------------------------------------------
1 file changed, 2 insertions(+), 48 deletions(-)
diff --git a/mm/hmm.c b/mm/hmm.c
index a491d9aaafe45d..3a2610e0713329 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -28,7 +28,6 @@
struct hmm_vma_walk {
struct hmm_range *range;
- struct dev_pagemap *pgmap;
unsigned long last;
unsigned int flags;
};
@@ -196,19 +195,8 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk,
unsigned long addr,
return hmm_vma_fault(addr, end, fault, write_fault, walk);
pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
- for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) {
- if (pmd_devmap(pmd)) {
- hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
- hmm_vma_walk->pgmap);
- if (unlikely(!hmm_vma_walk->pgmap))
- return -EBUSY;
- }
+ for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
pfns[i] = hmm_device_entry_from_pfn(range, pfn) | cpu_flags;
- }
- if (hmm_vma_walk->pgmap) {
- put_dev_pagemap(hmm_vma_walk->pgmap);
- hmm_vma_walk->pgmap = NULL;
- }
hmm_vma_walk->last = end;
return 0;
}
@@ -300,15 +288,6 @@ static int hmm_vma_handle_pte(struct mm_walk *walk,
unsigned long addr,
if (fault || write_fault)
goto fault;
- if (pte_devmap(pte)) {
- hmm_vma_walk->pgmap = get_dev_pagemap(pte_pfn(pte),
- hmm_vma_walk->pgmap);
- if (unlikely(!hmm_vma_walk->pgmap)) {
- pte_unmap(ptep);
- return -EBUSY;
- }
- }
-
/*
* Since each architecture defines a struct page for the zero page, just
* fall through and treat it like a normal page.
@@ -328,10 +307,6 @@ static int hmm_vma_handle_pte(struct mm_walk *walk,
unsigned long addr,
return 0;
fault:
- if (hmm_vma_walk->pgmap) {
- put_dev_pagemap(hmm_vma_walk->pgmap);
- hmm_vma_walk->pgmap = NULL;
- }
pte_unmap(ptep);
/* Fault any virtual address we were asked to fault */
return hmm_vma_fault(addr, end, fault, write_fault, walk);
@@ -418,16 +393,6 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
return r;
}
}
- if (hmm_vma_walk->pgmap) {
- /*
- * We do put_dev_pagemap() here and not in hmm_vma_handle_pte()
- * so that we can leverage get_dev_pagemap() optimization which
- * will not re-take a reference on a pgmap if we already have
- * one.
- */
- put_dev_pagemap(hmm_vma_walk->pgmap);
- hmm_vma_walk->pgmap = NULL;
- }
pte_unmap(ptep - 1);
hmm_vma_walk->last = addr;
@@ -491,20 +456,9 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long
start, unsigned long end,
}
pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
- for (i = 0; i < npages; ++i, ++pfn) {
- hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
- hmm_vma_walk->pgmap);
- if (unlikely(!hmm_vma_walk->pgmap)) {
- ret = -EBUSY;
- goto out_unlock;
- }
+ for (i = 0; i < npages; ++i, ++pfn)
pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
cpu_flags;
- }
- if (hmm_vma_walk->pgmap) {
- put_dev_pagemap(hmm_vma_walk->pgmap);
- hmm_vma_walk->pgmap = NULL;
- }
hmm_vma_walk->last = end;
goto out_unlock;
}
--
2.25.2
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