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X-CSE-ConnectionGUID: xrC67Tm4S7GcCWnCKgvN7A== X-CSE-MsgGUID: LERLuwtLTfaANRLNGD7LBQ== X-IronPort-AV: E=McAfee;i="6700,10204,11158"; a="31999469" X-IronPort-AV: E=Sophos;i="6.09,274,1716274800"; d="scan'208";a="31999469" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Aug 2024 18:29:03 -0700 X-CSE-ConnectionGUID: o1fcKy9AQMWzjENkrUWCwA== X-CSE-MsgGUID: Z3v00sjsS9+fKS1IpN7lUg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,274,1716274800"; d="scan'208";a="62252264" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Aug 2024 18:29:01 -0700 From: "Huang, Ying" To: Kefeng Wang Cc: Zi Yan , David Hildenbrand , "Andrew Morton" , Baolin Wang , , , Subject: Re: [PATCH 1/2] mm/numa: no task_numa_fault() call if page table is changed In-Reply-To: (Kefeng Wang's message of "Thu, 8 Aug 2024 22:36:59 +0800") References: <20240807184730.1266736-1-ziy@nvidia.com> <956553dc-587c-4a43-9877-7e8844f27f95@linux.alibaba.com> <1881267a-723d-4ba0-96d0-d863ae9345a4@redhat.com> <09AC6DFA-E50A-478D-A608-6EF08D8137E9@nvidia.com> <052552f4-5a8d-4799-8f02-177585a1c8dd@redhat.com> <8890DD6A-126A-406D-8AB9-97CF5A1F4DA4@nvidia.com> Date: Fri, 09 Aug 2024 09:25:27 +0800 Message-ID: <87cymizdvc.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Kefeng Wang writes: > On 2024/8/8 22:21, Zi Yan wrote: >> On 8 Aug 2024, at 10:14, David Hildenbrand wrote: >> >>> On 08.08.24 16:13, Zi Yan wrote: >>>> On 8 Aug 2024, at 4:22, David Hildenbrand wrote: >>>> >>>>> On 08.08.24 05:19, Baolin Wang wrote: >>>>>> >>>>>> > ... >>>>> Agreed, maybe we should simply handle that right away and replace the "goto out;" users by "return 0;". >>>>> >>>>> Then, just copy the 3 LOC. >>>>> >>>>> For mm/memory.c that would be: >>>>> >>>>> diff --git a/mm/memory.c b/mm/memory.c >>>>> index 67496dc5064f..410ba50ca746 100644 >>>>> --- a/mm/memory.c >>>>> +++ b/mm/memory.c >>>>> @@ -5461,7 +5461,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) >>>>> if (unlikely(!pte_same(old_pte, vmf->orig_pte))) { >>>>> pte_unmap_unlock(vmf->pte, vmf->ptl); >>>>> - goto out; >>>>> + return 0; >>>>> } >>>>> pte = pte_modify(old_pte, vma->vm_page_prot); >>>>> @@ -5528,15 +5528,14 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) >>>>> vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, >>>>> vmf->address, &vmf->ptl); >>>>> if (unlikely(!vmf->pte)) >>>>> - goto out; >>>>> + return 0; >>>>> if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { >>>>> pte_unmap_unlock(vmf->pte, vmf->ptl); >>>>> - goto out; >>>>> + return 0; >>>>> } >>>>> goto out_map; >>>>> } >>>>> -out: >>>>> if (nid != NUMA_NO_NODE) >>>>> task_numa_fault(last_cpupid, nid, nr_pages, flags); >>>>> return 0; > > Maybe drop this part too, > > diff --git a/mm/memory.c b/mm/memory.c > index 410ba50ca746..07343c1469e0 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -5523,6 +5523,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) > if (!migrate_misplaced_folio(folio, vma, target_nid)) { > nid = target_nid; > flags |= TNF_MIGRATED; > + goto out; > } else { > flags |= TNF_MIGRATE_FAIL; > vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, > @@ -5533,12 +5534,8 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) > pte_unmap_unlock(vmf->pte, vmf->ptl); > return 0; > } > - goto out_map; > } > > - if (nid != NUMA_NO_NODE) > - task_numa_fault(last_cpupid, nid, nr_pages, flags); > - return 0; > out_map: > /* > * Make it present again, depending on how arch implements IMHO, migration success is normal path, while migration failure is error processing path. If so, it's better to use "goto" for error processing instead of normal path. > @@ -5551,6 +5548,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) > numa_rebuild_single_mapping(vmf, vma, vmf->address, > vmf->pte, > writable); > pte_unmap_unlock(vmf->pte, vmf->ptl); > +out: > if (nid != NUMA_NO_NODE) > task_numa_fault(last_cpupid, nid, nr_pages, flags); > return 0; > > -- Best Regards, Huang, Ying