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[73.93.239.127]) by smtp.gmail.com with ESMTPSA id r11sm13456600pgl.34.2021.05.18.13.08.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 May 2021 13:08:32 -0700 (PDT) From: Yang Shi To: mgorman@suse.de, kirill.shutemov@linux.intel.com, ziy@nvidia.com, ying.huang@intel.com, mhocko@suse.com, hughd@google.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, akpm@linux-foundation.org Cc: shy828301@gmail.com, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [v3 PATCH 7/7] mm: thp: skip make PMD PROT_NONE if THP migration is not supported Date: Tue, 18 May 2021 13:08:01 -0700 Message-Id: <20210518200801.7413-8-shy828301@gmail.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210518200801.7413-1-shy828301@gmail.com> References: <20210518200801.7413-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A quick grep shows x86_64, PowerPC (book3s), ARM64 and S390 support both NUMA balancing and THP. But S390 doesn't support THP migration so NUMA balancing actually can't migrate any misplaced pages. Skip make PMD PROT_NONE for such case otherwise CPU cycles may be wasted by pointless NUMA hinting faults on S390. Acked-by: Mel Gorman Signed-off-by: Yang Shi --- mm/huge_memory.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b8526b9b041a..fb984ef5a761 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1735,6 +1735,7 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, * Returns * - 0 if PMD could not be locked * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary + * or if prot_numa but THP migration is not supported * - HPAGE_PMD_NR if protections changed and TLB flush necessary */ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, @@ -1749,6 +1750,9 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, bool uffd_wp = cp_flags & MM_CP_UFFD_WP; bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; + if (prot_numa && !thp_migration_supported()) + return 1; + ptl = __pmd_trans_huge_lock(pmd, vma); if (!ptl) return 0; -- 2.26.2