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Thu, 10 Sep 2020 13:27:14 -0700 Received: from intmgw002.41.prn1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Thu, 10 Sep 2020 13:27:10 -0700 Received: by devvm1096.prn0.facebook.com (Postfix, from userid 111017) id C0CB43D449BA; Thu, 10 Sep 2020 13:27:03 -0700 (PDT) Smtp-Origin-Hostprefix: devvm From: Roman Gushchin Smtp-Origin-Hostname: devvm1096.prn0.facebook.com To: Andrew Morton , CC: =Shakeel Butt , Johannes Weiner , Michal Hocko , , , Roman Gushchin Smtp-Origin-Cluster: prn0c01 Subject: [PATCH rfc 5/5] mm: convert page kmemcg type to a page memcg flag Date: Thu, 10 Sep 2020 13:26:59 -0700 Message-ID: <20200910202659.1378404-6-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200910202659.1378404-1-guro@fb.com> References: <20200910202659.1378404-1-guro@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-10_09:2020-09-10,2020-09-10 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 phishscore=0 adultscore=0 mlxscore=0 mlxlogscore=999 suspectscore=2 clxscore=1015 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009100183 X-FB-Internal: deliver X-Rspamd-Queue-Id: E08311004E11D X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: PageKmemcg flag is currently defined as a page type (like buddy, offline, table and guard). Semantically it means that the page was accounted as a kernel memory by the page allocator and has to be uncharged on the release. As a side effect of defining the flag as a page type, the accounted page can't be mapped to userspace (look at page_has_type() and comments above). In particular, this blocks the accounting of vmalloc-backed memory used by some bpf maps, because these maps do map the memory to userspace. One option is to fix it by complicating the access to page->mapcount, which provides some free bits for page->page_type. But it's way better to move this flag into page->memcg_data flags. Indeed, the flag makes no sense without enabled memory cgroups and memory cgroup pointer set in particular. This commit replaces PageKmemcg() and __SetPageKmemcg() with PageMemcgKmem() and SetPageMemcgKmem(). __ClearPageKmemcg() can be simple deleted because clear_page_mem_cgroup() already does the job. As a bonus, on !CONFIG_MEMCG build the PageMemcgKmem() check will be compiled out. Signed-off-by: Roman Gushchin --- include/linux/memcontrol.h | 35 ++++++++++++++++++++++++++++++++--- include/linux/page-flags.h | 11 ++--------- mm/memcontrol.c | 14 ++++---------- mm/page_alloc.c | 2 +- 4 files changed, 39 insertions(+), 23 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 7ab5f92bb686..430d1ca925c9 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -343,15 +343,22 @@ extern struct mem_cgroup *root_mem_cgroup; enum page_memcg_flags { /* page->memcg_data is a pointer to a objcgs vector */ PG_MEMCG_OBJ_CGROUPS, + /* page has been accounted as a non-slab kernel page */ + PG_MEMCG_KMEM, + /* the next bit after the last actual flag */ + PG_MEMCG_LAST_FLAG, }; =20 +#define MEMCG_FLAGS_MASK ((1UL << PG_MEMCG_LAST_FLAG) - 1) + static inline struct mem_cgroup *page_mem_cgroup(struct page *page) { unsigned long memcg_data =3D page->memcg_data; =20 VM_BUG_ON_PAGE(PageSlab(page), page); + VM_BUG_ON_PAGE(test_bit(PG_MEMCG_OBJ_CGROUPS, &memcg_data), page); =20 - return (struct mem_cgroup *)memcg_data; + return (struct mem_cgroup *)(memcg_data & ~MEMCG_FLAGS_MASK); } =20 static inline struct mem_cgroup *page_mem_cgroup_check(struct page *page= ) @@ -361,7 +368,7 @@ static inline struct mem_cgroup *page_mem_cgroup_chec= k(struct page *page) if (test_bit(PG_MEMCG_OBJ_CGROUPS, &memcg_data)) return NULL; =20 - return (struct mem_cgroup *)memcg_data; + return (struct mem_cgroup *)(memcg_data & ~MEMCG_FLAGS_MASK); } =20 static inline void set_page_mem_cgroup(struct page *page, @@ -377,6 +384,16 @@ static inline void clear_page_mem_cgroup(struct page= *page) page->memcg_data =3D 0; } =20 +static inline bool PageMemcgKmem(struct page *page) +{ + return test_bit(PG_MEMCG_KMEM, &page->memcg_data); +} + +static inline void SetPageMemcgKmem(struct page *page) +{ + __set_bit(PG_MEMCG_KMEM, &page->memcg_data); +} + #ifdef CONFIG_MEMCG_KMEM static inline struct obj_cgroup **page_obj_cgroups(struct page *page) { @@ -385,6 +402,7 @@ static inline struct obj_cgroup **page_obj_cgroups(st= ruct page *page) VM_BUG_ON_PAGE(memcg_data && !test_bit(PG_MEMCG_OBJ_CGROUPS, &memcg_data), page); __clear_bit(PG_MEMCG_OBJ_CGROUPS, &memcg_data); + VM_BUG_ON_PAGE(test_bit(PG_MEMCG_KMEM, &memcg_data), page); =20 return (struct obj_cgroup **)memcg_data; } @@ -393,8 +411,10 @@ static inline struct obj_cgroup **page_obj_cgroups_c= heck(struct page *page) { unsigned long memcg_data =3D page->memcg_data; =20 - if (memcg_data && test_bit(PG_MEMCG_OBJ_CGROUPS, &memcg_data)) + if (memcg_data && test_bit(PG_MEMCG_OBJ_CGROUPS, &memcg_data)) { + VM_BUG_ON_PAGE(test_bit(PG_MEMCG_KMEM, &memcg_data), page); return (struct obj_cgroup **)memcg_data; + } =20 return NULL; } @@ -1052,6 +1072,15 @@ static inline void clear_page_mem_cgroup(struct pa= ge *page) { } =20 +static inline bool PageMemcgKmem(struct page *page) +{ + return false; +} + +static inline void SetPageMemcgKmem(struct page *page) +{ +} + static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) { return true; diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index fbbb841a9346..a7ca01ae78d9 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -712,9 +712,8 @@ PAGEFLAG_FALSE(DoubleMap) #define PAGE_MAPCOUNT_RESERVE -128 #define PG_buddy 0x00000080 #define PG_offline 0x00000100 -#define PG_kmemcg 0x00000200 -#define PG_table 0x00000400 -#define PG_guard 0x00000800 +#define PG_table 0x00000200 +#define PG_guard 0x00000400 =20 #define PageType(page, flag) \ ((page->page_type & (PAGE_TYPE_BASE | flag)) =3D=3D PAGE_TYPE_BASE) @@ -765,12 +764,6 @@ PAGE_TYPE_OPS(Buddy, buddy) */ PAGE_TYPE_OPS(Offline, offline) =20 -/* - * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on - * pages allocated with __GFP_ACCOUNT. It gets cleared on page free. - */ -PAGE_TYPE_OPS(Kmemcg, kmemcg) - /* * Marks pages in use as page tables. */ diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ba9b053b1b88..d4c21870dab9 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3070,7 +3070,7 @@ int __memcg_kmem_charge_page(struct page *page, gfp= _t gfp, int order) ret =3D __memcg_kmem_charge(memcg, gfp, 1 << order); if (!ret) { set_page_mem_cgroup(page, memcg); - __SetPageKmemcg(page); + SetPageMemcgKmem(page); return 0; } css_put(&memcg->css); @@ -3095,10 +3095,6 @@ void __memcg_kmem_uncharge_page(struct page *page,= int order) __memcg_kmem_uncharge(memcg, nr_pages); clear_page_mem_cgroup(page); css_put(&memcg->css); - - /* slab pages do not have PageKmemcg flag set */ - if (PageKmemcg(page)) - __ClearPageKmemcg(page); } =20 static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_= bytes) @@ -6830,12 +6826,10 @@ static void uncharge_page(struct page *page, stru= ct uncharge_gather *ug) nr_pages =3D compound_nr(page); ug->nr_pages +=3D nr_pages; =20 - if (!PageKmemcg(page)) { - ug->pgpgout++; - } else { + if (PageMemcgKmem(page)) ug->nr_kmem +=3D nr_pages; - __ClearPageKmemcg(page); - } + else + ug->pgpgout++; =20 ug->dummy_page =3D page; clear_page_mem_cgroup(page); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index a707671f3b6c..3a61868113ec 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1197,7 +1197,7 @@ static __always_inline bool free_pages_prepare(stru= ct page *page, } if (PageMappingFlags(page)) page->mapping =3D NULL; - if (memcg_kmem_enabled() && PageKmemcg(page)) + if (memcg_kmem_enabled() && PageMemcgKmem(page)) __memcg_kmem_uncharge_page(page, order); if (check_free) bad +=3D check_free_page(page); --=20 2.26.2