On 2021/9/2 20:16, David Hildenbrand wrote: > On 02.09.21 14:12, Miaohe Lin wrote: >> Don't use with __GFP_HIGHMEM because page_address() cannot represent >> highmem pages without kmap(). Newly allocated pages would leak as >> page_address() will return NULL for highmem pages here. But It works >> now because the callers do not specify __GFP_HIGHMEM now. >> >> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> >> --- >> mm/page_alloc.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 9c09dcb24149..e1d0e27d005a 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -5614,8 +5614,8 @@ void *alloc_pages_exact(size_t size, gfp_t gfp_mask) >> unsigned int order = get_order(size); >> unsigned long addr; >> - if (WARN_ON_ONCE(gfp_mask & __GFP_COMP)) >> - gfp_mask &= ~__GFP_COMP; >> + if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM))) >> + gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM); >> addr = __get_free_pages(gfp_mask, order); >> return make_alloc_exact(addr, order, size); >> @@ -5639,8 +5639,8 @@ void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask) >> unsigned int order = get_order(size); >> struct page *p; >> - if (WARN_ON_ONCE(gfp_mask & __GFP_COMP)) >> - gfp_mask &= ~__GFP_COMP; >> + if (WARN_ON_ONCE(gfp_mask & (__GFP_COMP | __GFP_HIGHMEM))) >> + gfp_mask &= ~(__GFP_COMP | __GFP_HIGHMEM); >> p = alloc_pages_node(nid, gfp_mask, order); >> if (!p) >> > > Ideally we would convert this WARN_ON_ONCE() to pr_warn_once(), but I guess this really never ever happens on a production system and would get caught early while testing. > This patch is mainly intended to make it clear that we simply can't call alloc_pages_exact[_nid] with GFP_HIGHMEM. So this warning would never ever happens. > Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> > Many thanks for your review and reply.
