On Thu, Mar 04, 2021 at 07:40:53AM +0000, Zhou Guanghui wrote: > As described in the split_page function comment, for the non-compound > high order page, the sub-pages must be freed individually. If the > memcg of the fisrt page is valid, the tail pages cannot be uncharged > when be freed. > > For example, when alloc_pages_exact is used to allocate 1MB continuous > physical memory, 2MB is charged(kmemcg is enabled and __GFP_ACCOUNT is > set). When make_alloc_exact free the unused 1MB and free_pages_exact > free the applied 1MB, actually, only 4KB(one page) is uncharged. > > Therefore, the memcg of the tail page needs to be set when split page. > > Signed-off-by: Zhou Guanghui <zhouguanghui1@xxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
