On Sat, Jun 27, 2020 at 04:55:07AM +0000, Long Li wrote: > Environment using the slub allocator, 1G memory in my ARM32. > kmalloc(1024, GFP_HIGHUSER) can allocate memory normally, > kmalloc(64*1024, GFP_HIGHUSER) will cause a memory leak, because > alloc_pages returns highmem physical pages, but it cannot be directly > converted into a virtual address and return NULL, the pages has not > been released. Usually driver developers will not use the > GFP_HIGHUSER flag to allocate memory in kmalloc, but I think this > memory leak is not perfect, it is best to be fixed. This is the > first time I have posted a patch, there may be something wrong.
Slab used to disallow GFP_HIGHMEM allocations earlier than this, so you'd never get here. See one moron's patch here, 20 years ago ... https://lore.kernel.org/lkml/20001228145801.c19...@parcelfarce.linux.theplanet.co.uk/ Things changed a bit since then. SLAB_LEVEL_MASK became GFP_SLAB_BUG_MASK, then GFP_SLAB_BUG_MASK moved to mm/internal.h. Nowadays, GFP_SLAB_BUG_MASK is checked only in new_slab(), and it is definitely skipped when we go through the kmalloc_large() patch. Could you send a replacement patch which checks GFP_SLAB_BUG_MASK before calling alloc_pages()? > +++ b/mm/slab_common.c > @@ -819,8 +819,12 @@ void *kmalloc_order(size_t size, gfp_t flags, unsigned > int order) > page = alloc_pages(flags, order); > if (likely(page)) { > ret = page_address(page); > - mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B, > - PAGE_SIZE << order); > + if (ret) > + mod_node_page_state(page_pgdat(page), > + NR_SLAB_UNRECLAIMABLE_B, > + PAGE_SIZE << order); > + else > + __free_pages(page, order); > } > ret = kasan_kmalloc_large(ret, size, flags); > /* As ret might get tagged, call kmemleak hook after KASAN. */ > -- > 2.17.1 > >
