| Message ID | 20241026054307.3896926-2-wangkefeng.wang@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] mm: use aligned address in clear_gigantic_page() | expand |
On 26.10.24 07:43, Kefeng Wang wrote: > When copying gigantic page, it copies page from the first page to the > last page, if directly passing addr_hint which maybe not the address > of the first page of folio, then some archs could flush the wrong cache > if it does use the addr_hint as a hint. For non-gigantic page, it > calculates the base address inside, even passed the wrong addr_hint, it > only has performance impact as the process_huge_page() wants to process > target page last to keep its cache lines hot), no functional impact. > > Let's pass the real accessed address to copy_user_large_folio() and use > the aligned address in copy_user_gigantic_page() to fix it. > > Fixes: 530dd9926dc1 ("mm: memory: improve copy_user_large_folio()") > Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> > --- > v2: > - update changelog to clarify the impact, per Andrew > > mm/hugetlb.c | 5 ++--- > mm/memory.c | 1 + > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 2c8c5da0f5d3..15b5d46d49d2 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -5338,7 +5338,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, > break; > } > ret = copy_user_large_folio(new_folio, pte_folio, > - ALIGN_DOWN(addr, sz), dst_vma); > + addr, dst_vma); > folio_put(pte_folio); > if (ret) { > folio_put(new_folio); > @@ -6641,8 +6641,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte, > *foliop = NULL; > goto out; > } > - ret = copy_user_large_folio(folio, *foliop, > - ALIGN_DOWN(dst_addr, size), dst_vma); > + ret = copy_user_large_folio(folio, *foliop, dst_addr, dst_vma); > folio_put(*foliop); > *foliop = NULL; > if (ret) { > diff --git a/mm/memory.c b/mm/memory.c > index ef47b7ea5ddd..e5284bab659d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -6860,6 +6860,7 @@ static int copy_user_gigantic_page(struct folio *dst, struct folio *src, > struct page *dst_page; > struct page *src_page; > > + addr = ALIGN_DOWN(addr, folio_size(dst)); Same thing, please make it clearer that there is an "addr_hint" and an "addr".
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 2c8c5da0f5d3..15b5d46d49d2 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5338,7 +5338,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, break; } ret = copy_user_large_folio(new_folio, pte_folio, - ALIGN_DOWN(addr, sz), dst_vma); + addr, dst_vma); folio_put(pte_folio); if (ret) { folio_put(new_folio); @@ -6641,8 +6641,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte, *foliop = NULL; goto out; } - ret = copy_user_large_folio(folio, *foliop, - ALIGN_DOWN(dst_addr, size), dst_vma); + ret = copy_user_large_folio(folio, *foliop, dst_addr, dst_vma); folio_put(*foliop); *foliop = NULL; if (ret) { diff --git a/mm/memory.c b/mm/memory.c index ef47b7ea5ddd..e5284bab659d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -6860,6 +6860,7 @@ static int copy_user_gigantic_page(struct folio *dst, struct folio *src, struct page *dst_page; struct page *src_page; + addr = ALIGN_DOWN(addr, folio_size(dst)); for (i = 0; i < nr_pages; i++) { dst_page = folio_page(dst, i); src_page = folio_page(src, i);
When copying gigantic page, it copies page from the first page to the last page, if directly passing addr_hint which maybe not the address of the first page of folio, then some archs could flush the wrong cache if it does use the addr_hint as a hint. For non-gigantic page, it calculates the base address inside, even passed the wrong addr_hint, it only has performance impact as the process_huge_page() wants to process target page last to keep its cache lines hot), no functional impact. Let's pass the real accessed address to copy_user_large_folio() and use the aligned address in copy_user_gigantic_page() to fix it. Fixes: 530dd9926dc1 ("mm: memory: improve copy_user_large_folio()") Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> --- v2: - update changelog to clarify the impact, per Andrew mm/hugetlb.c | 5 ++--- mm/memory.c | 1 + 2 files changed, 3 insertions(+), 3 deletions(-)