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X-IronPort-AV: E=McAfee;i="6500,9779,10606"; a="329013848" X-IronPort-AV: E=Sophos;i="5.97,259,1669104000"; d="scan'208";a="329013848" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jan 2023 19:34:58 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10606"; a="993121025" X-IronPort-AV: E=Sophos;i="5.97,259,1669104000"; d="scan'208";a="993121025" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jan 2023 19:34:56 -0800 From: "Huang, Ying" To: Yin Fengwei Cc: , , , , Subject: Re: [RFC PATCH 2/5] filemap: do file page mapping with folio granularity References: <20230130125504.2509710-1-fengwei.yin@intel.com> <20230130125504.2509710-3-fengwei.yin@intel.com> Date: Tue, 31 Jan 2023 11:34:06 +0800 In-Reply-To: <20230130125504.2509710-3-fengwei.yin@intel.com> (Yin Fengwei's message of "Mon, 30 Jan 2023 20:55:01 +0800") Message-ID: <87v8kns7gx.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: 3tn8u4yt6913kjnu37gjapui3fx1w3uf X-Rspamd-Queue-Id: 33211120008 X-HE-Tag: 1675136099-723682 X-HE-Meta: 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 U+iaWZ8m YqhFDR8VZ+T/jMA1zKSl9zjleIXqkO4+h+TOuWgimM+TMaidTYHK526tltzMjOzIX1ZfTtZoS5EPSlaktVIuA15EypFk6d1u4B6d/gO/R9/4LmSxnewTJA1ZJJ68BMU6nKEHpnFrE9NlSTHEhomznBwmCiTcoAG8xWy/BmIHw9t+TJo8BDNnzTSotjg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Yin Fengwei writes: > Add function to do file page mapping based on folio and update > filemap_map_pages() to use new function. So the filemap page > mapping will deal with folio granularity instead of page > granularity. This allow batched folio refcount update. > > Signed-off-by: Yin Fengwei > --- > mm/filemap.c | 82 ++++++++++++++++++++++++++++++---------------------- > 1 file changed, 48 insertions(+), 34 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index c915ded191f0..fe0c226c8b1e 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -3351,6 +3351,43 @@ static inline struct folio *next_map_page(struct address_space *mapping, > mapping, xas, end_pgoff); > } > > + > +static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, > + struct folio *folio, struct page *page, unsigned long addr, > + int len) As Matthew pointed out, we should rename 'len'. And some comments about the meaning of the parameters should be good. For example, /* Map sub-pages [start_page, start_page + nr_pages) of folio */ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, struct folio *folio, struct page *start_page, unsigned int nr_pages, unsigned long start) Best Regards, Huang, Ying > +{ > + vm_fault_t ret = 0; > + struct vm_area_struct *vma = vmf->vma; > + struct file *file = vma->vm_file; > + unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss); > + int ref_count = 0, count = 0; > + > + do { > + if (PageHWPoison(page)) > + continue; > + > + if (mmap_miss > 0) > + mmap_miss--; > + > + if (!pte_none(*vmf->pte)) > + continue; > + > + if (vmf->address == addr) > + ret = VM_FAULT_NOPAGE; > + > + ref_count++; > + > + do_set_pte(vmf, page, addr); > + update_mmu_cache(vma, addr, vmf->pte); > + > + } while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < len); > + > + folio_ref_add(folio, ref_count); > + WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss); > + > + return ret; > +} > + > vm_fault_t filemap_map_pages(struct vm_fault *vmf, > pgoff_t start_pgoff, pgoff_t end_pgoff) > { > @@ -3361,9 +3398,9 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, > unsigned long addr; > XA_STATE(xas, &mapping->i_pages, start_pgoff); > struct folio *folio; > - struct page *page; > unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss); > vm_fault_t ret = 0; > + int len = 0; > > rcu_read_lock(); > folio = first_map_page(mapping, &xas, end_pgoff); > @@ -3378,45 +3415,22 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, > addr = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT); > vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl); > do { > -again: > - page = folio_file_page(folio, xas.xa_index); > - if (PageHWPoison(page)) > - goto unlock; > - > - if (mmap_miss > 0) > - mmap_miss--; > + struct page *page; > + unsigned long end; > > + page = folio_file_page(folio, xas.xa_index); > addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT; > - vmf->pte += xas.xa_index - last_pgoff; > + vmf->pte += xas.xa_index - last_pgoff - len; > last_pgoff = xas.xa_index; > + end = folio->index + folio_nr_pages(folio) - 1; > + len = min(end, end_pgoff) - xas.xa_index + 1; > > - /* > - * NOTE: If there're PTE markers, we'll leave them to be > - * handled in the specific fault path, and it'll prohibit the > - * fault-around logic. > - */ > - if (!pte_none(*vmf->pte)) > - goto unlock; > - > - /* We're about to handle the fault */ > - if (vmf->address == addr) > + if (VM_FAULT_NOPAGE == > + filemap_map_folio_range(vmf, folio, page, addr, len)) > ret = VM_FAULT_NOPAGE; > > - do_set_pte(vmf, page, addr); > - /* no need to invalidate: a not-present page won't be cached */ > - update_mmu_cache(vma, addr, vmf->pte); > - if (folio_more_pages(folio, xas.xa_index, end_pgoff)) { > - xas.xa_index++; > - folio_ref_inc(folio); > - goto again; > - } > - folio_unlock(folio); > - continue; > -unlock: > - if (folio_more_pages(folio, xas.xa_index, end_pgoff)) { > - xas.xa_index++; > - goto again; > - } > + xas.xa_index = end; > + > folio_unlock(folio); > folio_put(folio); > } while ((folio = next_map_page(mapping, &xas, end_pgoff)) != NULL);