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[70.52.229.124]) by smtp.gmail.com with ESMTPSA id a67-20020a254d46000000b00b8bfb4c4f1esm3139594ybb.62.2023.04.17.12.42.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Apr 2023 12:42:04 -0700 (PDT) Date: Mon, 17 Apr 2023 15:42:02 -0400 From: Peter Xu To: Muhammad Usama Anjum Cc: David Hildenbrand , Andrew Morton , =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Andrei Vagin , Danylo Mocherniuk , Paul Gofman , Cyrill Gorcunov , Mike Rapoport , Nadav Amit , Alexander Viro , Shuah Khan , Christian Brauner , Yang Shi , Vlastimil Babka , "Liam R . Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Matthew Wilcox , Pasha Tatashin , Axel Rasmussen , "Gustavo A . R . Silva" , Dan Williams , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Greg KH , kernel@collabora.com Subject: Re: [PATCH v13 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs Message-ID: References: <20230417125630.1146906-1-usama.anjum@collabora.com> <20230417125630.1146906-3-usama.anjum@collabora.com> MIME-Version: 1.0 In-Reply-To: <20230417125630.1146906-3-usama.anjum@collabora.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Rspamd-Queue-Id: 5950F8000D X-Rspamd-Server: rspam01 X-Stat-Signature: d78rudc3w87tpo3hsnyfjoknrhoeet8t X-HE-Tag: 1681760528-683717 X-HE-Meta: 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 nRpiAjYj cHKo07VxuRP3YesfN6lrlNgh6goaAcU/FAQwQImzTDzSCfTmqOhfibnoJV3jOWvTMmLmCLYzIHiyY+ByZMj8+CG/8g+WZaEPG3UcQaXf9bXLko589PKDaAGlzwT8HWmDyHeMjZDsYgy9PCr9SpFacRgnuunJ6nbt5b3kC9HSeZdzFcxGCQYcZT5Hz/hCqJZ4GHbtFwEXmW3hsR1G3wfvJzxHurtLUYAddB0Cm4xz4LbgtHq4rt3UElJlIDIGD7s3HhfsJPT5GhJVKTTqVRY6DnQCqXfavo7hEnv/LvHA8m8RYJAZSyIpmydNVn9wd9005oUqVwEAvrVZxebe86zB5IsqZxS8xYQc3WvmvRrWCX6/VZCKBBXWJnM3VlvDLB6GEXvhWYiHdA3Ox1cgO3TvhYCol/bxpjagHco8v4RtGvYYYp8g= 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: Muhammad, On Mon, Apr 17, 2023 at 05:56:27PM +0500, Muhammad Usama Anjum wrote: > +static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start, > + unsigned long end, struct mm_walk *walk) > +{ > + struct pagemap_scan_private *p = walk->private; > + struct vm_area_struct *vma = walk->vma; > + unsigned long addr = end; > + pte_t *pte, *orig_pte; > + spinlock_t *ptl; > + bool is_written; > + int ret = 0; > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > + ptl = pmd_trans_huge_lock(pmd, vma); > + if (ptl) { > + unsigned long n_pages = (end - start)/PAGE_SIZE; > + > + if (p->max_pages && n_pages > p->max_pages - p->found_pages) > + n_pages = p->max_pages - p->found_pages; > + > + is_written = !is_pmd_uffd_wp(*pmd); > + > + /* > + * Break huge page into small pages if the WP operation need to > + * be performed is on a portion of the huge page. > + */ > + if (is_written && PM_SCAN_DO_UFFD_WP(p) && > + n_pages < HPAGE_SIZE/PAGE_SIZE) { > + spin_unlock(ptl); > + split_huge_pmd(vma, pmd, start); > + goto process_smaller_pages; > + } > + > + ret = pagemap_scan_output(is_written, vma->vm_file, > + pmd_present(*pmd), is_swap_pmd(*pmd), > + p, start, n_pages); > + > + if (ret >= 0 && is_written && PM_SCAN_DO_UFFD_WP(p)) > + make_uffd_wp_pmd(vma, addr, pmd); > + > + spin_unlock(ptl); > + return ret; > + } > +process_smaller_pages: > + if (pmd_trans_unstable(pmd)) > + return 0; > +#endif > + > + pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl); > + for (addr = start; addr < end && !ret; pte++, addr += PAGE_SIZE) { > + is_written = !is_pte_uffd_wp(*pte); > + > + ret = pagemap_scan_output(is_written, vma->vm_file, > + pte_present(*pte), is_swap_pte(*pte), > + p, addr, 1); > + > + if (ret >= 0 && is_written && PM_SCAN_DO_UFFD_WP(p)) > + make_uffd_wp_pte(vma, addr, pte); > + } > + pte_unmap_unlock(orig_pte, ptl); IIUC tlb flushes, mmu notifications are still missing here, am I right? Thanks, > + > + cond_resched(); > + return ret; > +} -- Peter Xu