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Thu, 01 Oct 2020 06:46:32 -0700 (PDT) Date: Thu, 1 Oct 2020 09:44:52 -0400 From: Johannes Weiner To: Roman Gushchin Cc: Andrew Morton , Shakeel Butt , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com Subject: Re: [PATCH v4 3/4] mm: introduce page memcg flags Message-ID: <20201001134452.GD469663@cmpxchg.org> References: <20201001002710.748166-1-guro@fb.com> <20201001002710.748166-4-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201001002710.748166-4-guro@fb.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000023, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Sep 30, 2020 at 05:27:09PM -0700, Roman Gushchin wrote: > @@ -448,7 +451,12 @@ static inline void set_page_memcg(struct page *page, struct mem_cgroup *memcg) > */ > static inline struct obj_cgroup **page_objcgs(struct page *page) > { > - return (struct obj_cgroup **)(READ_ONCE(page->memcg_data) & ~0x1UL); > + unsigned long memcg_data = READ_ONCE(page->memcg_data); > + > + VM_BUG_ON_PAGE(memcg_data && > + !(memcg_data & MEMCG_DATA_OBJCGS), page); This fits on a single line. > + return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); > } > > /* > @@ -463,8 +471,9 @@ static inline struct obj_cgroup **page_objcgs_check(struct page *page) > { > unsigned long memcg_data = READ_ONCE(page->memcg_data); > > - if (memcg_data && (memcg_data & 0x1UL)) > - return (struct obj_cgroup **)(memcg_data & ~0x1UL); > + if (memcg_data && (memcg_data & MEMCG_DATA_OBJCGS)) > + return (struct obj_cgroup **) > + (memcg_data & ~MEMCG_DATA_FLAGS_MASK); if (!memcg_data || (memcg_data & MEMCG_DATA_OBJCGS)) return NULL; return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK); > @@ -479,7 +488,11 @@ static inline struct obj_cgroup **page_objcgs_check(struct page *page) > static inline bool set_page_objcgs(struct page *page, > struct obj_cgroup **objcgs) > { > - return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL); > + unsigned long memcg_data = (unsigned long)objcgs; > + > + memcg_data |= MEMCG_DATA_OBJCGS; > + > + return !cmpxchg(&page->memcg_data, 0, memcg_data); return !cmpxchg(&page->memcg_data, 0, memcg_data | MEMCG_DATA_OBJCGS);