From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zhenyu Ye Subject: Re: [RFC PATCH v5 4/8] mm: tlb: Pass struct mmu_gather to flush_pmd_tlb_range Date: Wed, 1 Apr 2020 16:51:15 +0800 Message-ID: References: <20200331142927.1237-1-yezhenyu2@huawei.com> <20200331142927.1237-5-yezhenyu2@huawei.com> <20200331151331.GS20730@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200331151331.GS20730@hirez.programming.kicks-ass.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane-mx.org@lists.infradead.org To: Peter Zijlstra Cc: mark.rutland@arm.com, catalin.marinas@arm.com, linux-mm@kvack.org, guohanjun@huawei.com, will@kernel.org, linux-arch@vger.kernel.org, yuzhao@google.com, corbet@lwn.net, maz@kernel.org, steven.price@arm.com, arm@kernel.org, Dave.Martin@arm.com, arnd@arndb.de, suzuki.poulose@arm.com, npiggin@gmail.com, zhangshaokun@hisilicon.com, broonie@kernel.org, rostedt@goodmis.org, prime.zeng@hisilicon.com, kuhn.chenqun@huawei.com, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, xiexiangyou@huawei.com, tony.luck@intel.com, vgupta@synopsys.com, linux-kernel@vger.kernel.org, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org List-Id: linux-arch.vger.kernel.org Hi Peter, On 2020/3/31 23:13, Peter Zijlstra wrote: > On Tue, Mar 31, 2020 at 10:29:23PM +0800, Zhenyu Ye wrote: >> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h >> index e2e2bef07dd2..32d4661e5a56 100644 >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -1160,10 +1160,10 @@ static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) >> * invalidate the entire TLB which is not desitable. >> * e.g. see arch/arc: flush_pmd_tlb_range >> */ >> -#define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >> +#define flush_pmd_tlb_range(tlb, vma, addr, end) flush_tlb_range(vma, addr, end) >> #define flush_pud_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >> #else >> -#define flush_pmd_tlb_range(vma, addr, end) BUILD_BUG() >> +#define flush_pmd_tlb_range(tlb, vma, addr, end) BUILD_BUG() >> #define flush_pud_tlb_range(vma, addr, end) BUILD_BUG() >> #endif >> #endif >> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c >> index 3d7c01e76efc..96c9cf77bfb5 100644 >> --- a/mm/pgtable-generic.c >> +++ b/mm/pgtable-generic.c >> @@ -109,8 +109,14 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, >> int changed = !pmd_same(*pmdp, entry); >> VM_BUG_ON(address & ~HPAGE_PMD_MASK); >> if (changed) { >> + struct mmu_gather tlb; >> + unsigned long tlb_start = address; >> + unsigned long tlb_end = address + HPAGE_PMD_SIZE; >> set_pmd_at(vma->vm_mm, address, pmdp, entry); >> - flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); >> + tlb_gather_mmu(&tlb, vma->vm_mm, tlb_start, tlb_end); >> + tlb.cleared_pmds = 1; >> + flush_pmd_tlb_range(&tlb, vma, tlb_start, tlb_end); >> + tlb_finish_mmu(&tlb, tlb_start, tlb_end); >> } >> return changed; >> } > > This is madness. Please, carefully consider what you just wrote and what > it will do in the generic case. > > Instead of trying to retro-fit flush_*tlb_range() to take an mmu_gather > parameter, please replace them out-right. > I'm sorry that I'm not sure what "replace them out-right" means. Do you mean that I should define flush_*_tlb_range like this? #define flush_pmd_tlb_range(vma, addr, end) \ do { \ struct mmu_gather tlb; \ tlb_gather_mmu(&tlb, (vma)->vm_mm, addr, end); \ tlba.cleared_pmds = 1; \ flush_tlb_range(&tlb, vma, addr, end); \ tlb_finish_mmu(&tlb, addr, end); \ } while (0) Thanks, Zhenyu From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [RFC PATCH v5 4/8] mm: tlb: Pass struct mmu_gather to flush_pmd_tlb_range References: <20200331142927.1237-1-yezhenyu2@huawei.com> <20200331142927.1237-5-yezhenyu2@huawei.com> <20200331151331.GS20730@hirez.programming.kicks-ass.net> From: Zhenyu Ye Message-ID: Date: Wed, 1 Apr 2020 16:51:15 +0800 MIME-Version: 1.0 In-Reply-To: <20200331151331.GS20730@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: mark.rutland@arm.com, will@kernel.org, catalin.marinas@arm.com, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org, npiggin@gmail.com, arnd@arndb.de, rostedt@goodmis.org, maz@kernel.org, suzuki.poulose@arm.com, tglx@linutronix.de, yuzhao@google.com, Dave.Martin@arm.com, steven.price@arm.com, broonie@kernel.org, guohanjun@huawei.com, corbet@lwn.net, vgupta@synopsys.com, tony.luck@intel.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, arm@kernel.org, xiexiangyou@huawei.com, prime.zeng@hisilicon.com, zhangshaokun@hisilicon.com, kuhn.chenqun@huawei.com List-ID: Message-ID: <20200401085115.SYQzoxS_n4RTrj36Q4n2k6GDT_pVd7zy7o2ZG3Af0Mo@z> Hi Peter, On 2020/3/31 23:13, Peter Zijlstra wrote: > On Tue, Mar 31, 2020 at 10:29:23PM +0800, Zhenyu Ye wrote: >> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h >> index e2e2bef07dd2..32d4661e5a56 100644 >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -1160,10 +1160,10 @@ static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) >> * invalidate the entire TLB which is not desitable. >> * e.g. see arch/arc: flush_pmd_tlb_range >> */ >> -#define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >> +#define flush_pmd_tlb_range(tlb, vma, addr, end) flush_tlb_range(vma, addr, end) >> #define flush_pud_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >> #else >> -#define flush_pmd_tlb_range(vma, addr, end) BUILD_BUG() >> +#define flush_pmd_tlb_range(tlb, vma, addr, end) BUILD_BUG() >> #define flush_pud_tlb_range(vma, addr, end) BUILD_BUG() >> #endif >> #endif >> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c >> index 3d7c01e76efc..96c9cf77bfb5 100644 >> --- a/mm/pgtable-generic.c >> +++ b/mm/pgtable-generic.c >> @@ -109,8 +109,14 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, >> int changed = !pmd_same(*pmdp, entry); >> VM_BUG_ON(address & ~HPAGE_PMD_MASK); >> if (changed) { >> + struct mmu_gather tlb; >> + unsigned long tlb_start = address; >> + unsigned long tlb_end = address + HPAGE_PMD_SIZE; >> set_pmd_at(vma->vm_mm, address, pmdp, entry); >> - flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); >> + tlb_gather_mmu(&tlb, vma->vm_mm, tlb_start, tlb_end); >> + tlb.cleared_pmds = 1; >> + flush_pmd_tlb_range(&tlb, vma, tlb_start, tlb_end); >> + tlb_finish_mmu(&tlb, tlb_start, tlb_end); >> } >> return changed; >> } > > This is madness. Please, carefully consider what you just wrote and what > it will do in the generic case. > > Instead of trying to retro-fit flush_*tlb_range() to take an mmu_gather > parameter, please replace them out-right. > I'm sorry that I'm not sure what "replace them out-right" means. Do you mean that I should define flush_*_tlb_range like this? #define flush_pmd_tlb_range(vma, addr, end) \ do { \ struct mmu_gather tlb; \ tlb_gather_mmu(&tlb, (vma)->vm_mm, addr, end); \ tlba.cleared_pmds = 1; \ flush_tlb_range(&tlb, vma, addr, end); \ tlb_finish_mmu(&tlb, addr, end); \ } while (0) Thanks, Zhenyu