On Thu, Mar 12, 2020 at 06:34:16AM -0700, Matthew Wilcox wrote: >On Thu, Mar 12, 2020 at 09:08:22PM +0800, Baoquan He wrote: >> This change makes populate_section_memmap()/depopulate_section_memmap >> much simpler. >> >> Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> >> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> >> --- >> v1->v2: >> The old version only used __get_free_pages() to replace alloc_pages() >> in populate_section_memmap(). >> http://lkml.kernel.org/r/20200307084229.28251-8-bhe@xxxxxxxxxx >> >> mm/sparse.c | 27 +++------------------------ >> 1 file changed, 3 insertions(+), 24 deletions(-) >> >> diff --git a/mm/sparse.c b/mm/sparse.c >> index bf6c00a28045..362018e82e22 100644 >> --- a/mm/sparse.c >> +++ b/mm/sparse.c >> @@ -734,35 +734,14 @@ static void free_map_bootmem(struct page *memmap) >> struct page * __meminit populate_section_memmap(unsigned long pfn, >> unsigned long nr_pages, int nid, struct vmem_altmap *altmap) >> { >> - struct page *page, *ret; >> - unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION; >> - >> - page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size)); >> - if (page) >> - goto got_map_page; >> - >> - ret = vmalloc(memmap_size); >> - if (ret) >> - goto got_map_ptr; >> - >> - return NULL; >> -got_map_page: >> - ret = (struct page *)pfn_to_kaddr(page_to_pfn(page)); >> -got_map_ptr: >> - >> - return ret; >> + return kvmalloc_node(sizeof(struct page) * PAGES_PER_SECTION, >> + GFP_KERNEL|__GFP_NOWARN, nid); > >Use of NOWARN here is inappropriate, because there's no fallback. Hmm... this replacement is a little tricky. When you look into kvmalloc_node(), it will do the fallback if the size is bigger than PAGE_SIZE. This means the change here may not be equivalent as before if memmap_size is less than PAGE_SIZE. For example if : PAGE_SIZE = 64K SECTION_SIZE = 128M would lead to memmap_size = 2K, which is less than PAGE_SIZE. Not sure this combination would happen? >Also, I'd use array_size(sizeof(struct page), PAGES_PER_SECTION). -- Wei Yang Help you, Help me
