| Message ID | 20220329130928.266323-3-chenwandun@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fix several contiguous memmap assumptions | expand |
On Tue, Mar 29, 2022 at 09:09:28PM +0800, Chen Wandun wrote: > +#define page_nth(head, tail) (page_to_pfn(tail) - page_to_pfn(head)) Could we avoid reintroducing page_nth()? It is a terrible name. > @@ -1213,7 +1213,7 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) > ret = 0; > goto out; > } > - switch (page - head_page) { > + switch (page_nth(head_page, page)) { > case 1: > /* the first tail page: ->mapping may be compound_mapcount() */ > if (unlikely(compound_mapcount(page))) { This is the only place you use it. I'd suggest free_tail_pages_check() should take 'i' as its second parameter instead of 'page + i', then there's no need to convert back to i.
on 2022/3/29 21:08, Matthew Wilcox wrote: > On Tue, Mar 29, 2022 at 09:09:28PM +0800, Chen Wandun wrote: >> +#define page_nth(head, tail) (page_to_pfn(tail) - page_to_pfn(head)) > Could we avoid reintroducing page_nth()? It is a terrible name. how about compound_index ? >> @@ -1213,7 +1213,7 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) >> ret = 0; >> goto out; >> } >> - switch (page - head_page) { >> + switch (page_nth(head_page, page)) { >> case 1: >> /* the first tail page: ->mapping may be compound_mapcount() */ >> if (unlikely(compound_mapcount(page))) { > This is the only place you use it. I'd suggest free_tail_pages_check() > should take 'i' as its second parameter instead of 'page + i', then > there's no need to convert back to i. OK， I will send v2， but I'm not sure whether similar function like page_nth is needed elsewhere > > .
diff --git a/include/linux/mm.h b/include/linux/mm.h index 355075fb2654..ef48cfef7c67 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -212,9 +212,11 @@ int overcommit_policy_handler(struct ctl_table *, int, void *, size_t *, #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n)) +#define page_nth(head, tail) (page_to_pfn(tail) - page_to_pfn(head)) #define folio_page_idx(folio, p) (page_to_pfn(p) - folio_pfn(folio)) #else #define nth_page(page,n) ((page) + (n)) +#define page_nth(head, tail) ((tail) - (head)) #define folio_page_idx(folio, p) ((p) - &(folio)->page) #endif diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 855211dea13e..09bc63992d20 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -721,7 +721,7 @@ static void prep_compound_head(struct page *page, unsigned int order) static void prep_compound_tail(struct page *head, int tail_idx) { - struct page *p = head + tail_idx; + struct page *p = nth_page(head, tail_idx); p->mapping = TAIL_MAPPING; set_compound_head(p, head); @@ -1213,7 +1213,7 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) ret = 0; goto out; } - switch (page - head_page) { + switch (page_nth(head_page, page)) { case 1: /* the first tail page: ->mapping may be compound_mapcount() */ if (unlikely(compound_mapcount(page))) { @@ -1322,6 +1322,7 @@ static __always_inline bool free_pages_prepare(struct page *page, if (unlikely(order)) { bool compound = PageCompound(page); int i; + struct page *tail_page; VM_BUG_ON_PAGE(compound && compound_order(page) != order, page); @@ -1330,13 +1331,14 @@ static __always_inline bool free_pages_prepare(struct page *page, ClearPageHasHWPoisoned(page); } for (i = 1; i < (1 << order); i++) { + tail_page = nth_page(page, i); if (compound) - bad += free_tail_pages_check(page, page + i); - if (unlikely(check_free_page(page + i))) { + bad += free_tail_pages_check(page, tail_page); + if (unlikely(check_free_page(tail_page))) { bad++; continue; } - (page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; + tail_page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; } } if (PageMappingFlags(page))
It isn't true for only SPARSEMEM configs to assume that a compound page has virtually contiguous page structs, so use nth_page to iterate each page. Signed-off-by: Chen Wandun <chenwandun@huawei.com> --- include/linux/mm.h | 2 ++ mm/page_alloc.c | 12 +++++++----- 2 files changed, 9 insertions(+), 5 deletions(-)