Messages in this thread | | | Date | Mon, 10 Jan 2022 22:44:30 -0800 | Subject | Re: [PATCH v2 17/28] gup: Add gup_put_folio() | From | John Hubbard <> |
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On 1/9/22 20:23, Matthew Wilcox (Oracle) wrote: > Convert put_compound_head() to gup_put_folio() and hpage_pincount_sub() > to folio_pincount_sub(). This removes the last call to put_page_refs(), > so delete it. Add a temporary put_compound_head() wrapper which will > be deleted by the end of this series. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > mm/gup.c | 42 ++++++++++++++---------------------------- > 1 file changed, 14 insertions(+), 28 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 9e581201d679..719252fa0402 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -45,34 +45,15 @@ static void folio_pincount_add(struct folio *folio, int refs) > folio_ref_add(folio, refs * (GUP_PIN_COUNTING_BIAS - 1)); > } > > -static int page_pincount_sub(struct page *page, int refs) > +static int folio_pincount_sub(struct folio *folio, int refs)
I just noticed that this return value was a little hard to reason about, which prompted me to notice that I'd skipped reviewing patch 10. So I went back and added a note there. :)
Anyway, this one looks good,
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
thanks, -- John Hubbard NVIDIA
> { > - VM_BUG_ON_PAGE(page != compound_head(page), page); > - > - if (PageHead(page)) > - atomic_sub(refs, compound_pincount_ptr(page)); > + if (folio_test_large(folio)) > + atomic_sub(refs, folio_pincount_ptr(folio)); > else > refs *= GUP_PIN_COUNTING_BIAS; > return refs; > } > > -/* Equivalent to calling put_page() @refs times. */ > -static void put_page_refs(struct page *page, int refs) > -{ > -#ifdef CONFIG_DEBUG_VM > - if (VM_WARN_ON_ONCE_PAGE(page_ref_count(page) < refs, page)) > - return; > -#endif > - > - /* > - * Calling put_page() for each ref is unnecessarily slow. Only the last > - * ref needs a put_page(). > - */ > - if (refs > 1) > - page_ref_sub(page, refs - 1); > - put_page(page); > -} > - > /* > * Return the folio with ref appropriately incremented, > * or NULL if that failed. > @@ -171,15 +152,20 @@ struct page *try_grab_compound_head(struct page *page, > return &try_grab_folio(page, refs, flags)->page; > } > > -static void put_compound_head(struct page *page, int refs, unsigned int flags) > +static void gup_put_folio(struct folio *folio, int refs, unsigned int flags) > { > if (flags & FOLL_PIN) { > - mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED, > - refs); > - refs = page_pincount_sub(page, refs); > + node_stat_mod_folio(folio, NR_FOLL_PIN_RELEASED, refs); > + refs = folio_pincount_sub(folio, refs); > } > > - put_page_refs(page, refs); > + folio_put_refs(folio, refs); > +} > + > +static void put_compound_head(struct page *page, int refs, unsigned int flags) > +{ > + VM_BUG_ON_PAGE(PageTail(page), page); > + gup_put_folio((struct folio *)page, refs, flags); > } > > /** > @@ -220,7 +206,7 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags) > */ > void unpin_user_page(struct page *page) > { > - put_compound_head(compound_head(page), 1, FOLL_PIN); > + gup_put_folio(page_folio(page), 1, FOLL_PIN); > } > EXPORT_SYMBOL(unpin_user_page); >
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