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[67.174.241.145]) by smtp.gmail.com with ESMTPSA id w2-20020a62c702000000b006d9a0059a9asm2173490pfg.172.2024.01.09.11.31.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jan 2024 11:31:55 -0800 (PST) From: Yang Shi To: oliver.sang@intel.com, riel@surriel.com, fengwei.yin@intel.com, willy@infradead.org, cl@linux.com, ying.huang@intel.com, akpm@linux-foundation.org Cc: shy828301@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 2/2] mm: mmap: map MAP_STACK to VM_NOHUGEPAGE Date: Wed, 20 Dec 2023 22:59:43 -0800 Message-Id: <20231221065943.2803551-2-shy828301@gmail.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20231221065943.2803551-1-shy828301@gmail.com> References: <20231221065943.2803551-1-shy828301@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Yang Shi The commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") incured regression for stress-ng pthread benchmark [1]. It is because THP get allocated to pthread's stack area much more possible than before. Pthread's stack area is allocated by mmap without VM_GROWSDOWN or VM_GROWSUP flag, so kernel can't tell whether it is a stack area or not. The MAP_STACK flag is used to mark the stack area, but it is a no-op on Linux. Mapping MAP_STACK to VM_NOHUGEPAGE to prevent from allocating THP for such stack area. With this change the stack area looks like: fffd18e10000-fffd19610000 rw-p 00000000 00:00 0 Size: 8192 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Rss: 12 kB Pss: 12 kB Pss_Dirty: 12 kB Shared_Clean: 0 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 12 kB Referenced: 12 kB Anonymous: 12 kB KSM: 0 kB LazyFree: 0 kB AnonHugePages: 0 kB ShmemPmdMapped: 0 kB FilePmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB Locked: 0 kB THPeligible: 0 VmFlags: rd wr mr mw me ac nh The "nh" flag is set. [1] https://lore.kernel.org/linux-mm/202312192310.56367035-oliver.sang@intel.com/ Reported-by: kernel test robot Tested-by: Oliver Sang Cc: Yin Fengwei Cc: Rik van Riel Cc: Matthew Wilcox Cc: Christopher Lameter Cc: Huang, Ying Signed-off-by: Yang Shi --- include/linux/mman.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/mman.h b/include/linux/mman.h index 40d94411d492..dc7048824be8 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -156,6 +156,7 @@ calc_vm_flag_bits(unsigned long flags) return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) | _calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) | _calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) | + _calc_vm_trans(flags, MAP_STACK, VM_NOHUGEPAGE) | arch_calc_vm_flag_bits(flags); } -- 2.41.0