Messages in this thread Patch in this message | | | From | peterx@redhat ... | Subject | [PATCH 01/13] mm/hmm: Process pud swap entry without pud_huge() | Date | Wed, 13 Mar 2024 17:47:07 -0400 |
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From: Peter Xu <peterx@redhat.com>
Swap pud entries do not always return true for pud_huge() for all archs. x86 and sparc (so far) allow it, but all the rest do not accept a swap entry to be reported as pud_huge(). So it's not safe to check swap entries within pud_huge(). Check swap entries before pud_huge(), so it should be always safe.
This is the only place in the kernel that (IMHO, wrongly) relies on pud_huge() to return true on pud swap entries. The plan is to cleanup pXd_huge() to only report non-swap mappings for all archs.
Cc: Alistair Popple <apopple@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Peter Xu <peterx@redhat.com> --- mm/hmm.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/mm/hmm.c b/mm/hmm.c index 277ddcab4947..c95b9ec5d95f 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -424,7 +424,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, walk->action = ACTION_CONTINUE; pud = READ_ONCE(*pudp); - if (pud_none(pud)) { + if (!pud_present(pud)) { spin_unlock(ptl); return hmm_vma_walk_hole(start, end, -1, walk); } @@ -435,11 +435,6 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, unsigned long *hmm_pfns; unsigned long cpu_flags; - if (!pud_present(pud)) { - spin_unlock(ptl); - return hmm_vma_walk_hole(start, end, -1, walk); - } - i = (addr - range->start) >> PAGE_SHIFT; npages = (end - addr) >> PAGE_SHIFT; hmm_pfns = &range->hmm_pfns[i]; -- 2.44.0
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