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[98.15.154.102]) by smtp.gmail.com with ESMTPSA id b20sm7191158qtx.89.2021.10.12.11.02.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Oct 2021 11:02:02 -0700 (PDT) From: Johannes Weiner To: linux-mm@kvack.org Cc: Matthew Wilcox , Kent Overstreet , "Kirill A. Shutemov" , Vlastimil Babka , Michal Hocko , Roman Gushchin , linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 11/11] PageSlab: eliminate unnecessary compound_head() calls in mm/memcontrol Date: Tue, 12 Oct 2021 14:01:48 -0400 Message-Id: <20211012180148.1669685-12-hannes@cmpxchg.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211012180148.1669685-1-hannes@cmpxchg.org> References: <20211012180148.1669685-1-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org page->memcg_data is generally not valid on tailpages, so the accessor functions don't need to worry about encountering them outside of bugs. The only place where the memory controller may encounter tail pages is in mem_cgroup_from_obj(), but that uses virt_to_head_page() first thing to resolve slab objects to slab pages. Signed-off-by: Johannes Weiner --- include/linux/memcontrol.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 02394f802698..3096c9a0ee01 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -397,7 +397,7 @@ static inline struct mem_cgroup *__page_memcg(struct page *page) { unsigned long memcg_data = page->memcg_data; - VM_BUG_ON_PAGE(PageSlab(compound_head(page)), page); + VM_BUG_ON_PAGE(PageSlab(page), page); VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page); VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, page); @@ -418,7 +418,7 @@ static inline struct obj_cgroup *__page_objcg(struct page *page) { unsigned long memcg_data = page->memcg_data; - VM_BUG_ON_PAGE(PageSlab(compound_head(page)), page); + VM_BUG_ON_PAGE(PageSlab(page), page); VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page); VM_BUG_ON_PAGE(!(memcg_data & MEMCG_DATA_KMEM), page); @@ -466,7 +466,7 @@ static inline struct mem_cgroup *page_memcg_rcu(struct page *page) { unsigned long memcg_data = READ_ONCE(page->memcg_data); - VM_BUG_ON_PAGE(PageSlab(compound_head(page)), page); + VM_BUG_ON_PAGE(PageSlab(page), page); WARN_ON_ONCE(!rcu_read_lock_held()); if (memcg_data & MEMCG_DATA_KMEM) { -- 2.32.0