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R . Silva" , "Liam R . Howlett" , Matthew Wilcox , =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Mike Rapoport , Nadav Amit , Pasha Tatashin , Paul Gofman , Peter Xu , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , Yang Shi , Yun Zhou , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, kernel@collabora.com Subject: Re: [v2] fs/proc/task_mmu: Implement IOCTL for efficient page table scanning Content-Language: en-US To: =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= References: <20230713101415.108875-6-usama.anjum@collabora.com> <7eedf953-7cf6-c342-8fa8-b7626d69ab63@collabora.com> <382f4435-2088-08ce-20e9-bc1a15050861@collabora.com> From: Muhammad Usama Anjum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 79ACF400DB X-Rspam-User: X-Stat-Signature: 84woqdicgwinhe15nce18ustono6n96i X-Rspamd-Server: rspam01 X-HE-Tag: 1690207483-198637 X-HE-Meta: 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 7PEGRiDK C33ZeMiC6gMI+67TxuEXITcr/+Rd2nSDOfWCG5BHe+Dsf3XQwPZBluUSeUBKMPvM4tbezUT4/l+dvbfHH/gDn6Bbao2Kh7V8O5/f06WP3oPzPABsQ4gkyNgPtnw1MzB4V1th5l8adXma+fqMR3iANjAUr9ou3qruETANdL5NLZatNl9RUf/tTtkO4a+qPSc2JIklvv4bimlcMNT0FbmDZs3KQV8KS1jGfEoHvej+zTFcuG6Pt0Br3IhSww54itAa2p6WLFGRzjGXcnDY0GapDkQ/sOBCfPYRmJGmK9KFgbP3JR2ybgg7S+jlskw== 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: Fixed found bugs. Testing it further. - Split and backoff in case buffer full case as well - Fix the wrong breaking of loop if page isn't interesting, skip intead - Untag the address and save them into struct - Round off the end address to next page Signed-off-by: Muhammad Usama Anjum --- fs/proc/task_mmu.c | 54 ++++++++++++++++++++++++++-------------------- 1 file changed, 31 insertions(+), 23 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index add21fdf3c9a..64b326d0ec6d 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1764,7 +1764,8 @@ struct pagemap_scan_private { struct page_region __user* vec_out; }; -static unsigned long pagemap_page_category(struct vm_area_struct *vma, unsigned long addr, pte_t pte) +static unsigned long pagemap_page_category(struct vm_area_struct *vma, + unsigned long addr, pte_t pte) { unsigned long categories = 0; @@ -1908,6 +1909,7 @@ static bool pagemap_scan_is_interesting_vma(unsigned long categories, categories ^= p->arg.category_inverted; if ((categories & required) != required) return false; + return true; } @@ -1930,6 +1932,7 @@ static int pagemap_scan_test_walk(unsigned long start, unsigned long end, return 1; p->cur_vma_category = vma_category; + return 0; } @@ -1961,6 +1964,7 @@ static bool pagemap_scan_push_range(unsigned long categories, cur_buf->start = addr; cur_buf->end = end; cur_buf->categories = categories; + return true; } @@ -1985,18 +1989,19 @@ static int pagemap_scan_output(unsigned long categories, unsigned long n_pages, total_pages; int ret = 0; + if (!p->vec_buf) + return 0; + if (!pagemap_scan_is_interesting_page(categories, p)) { *end = addr; return 0; } - if (!p->vec_buf) - return 0; - categories &= p->arg.return_mask; n_pages = (*end - addr) / PAGE_SIZE; - if (check_add_overflow(p->found_pages, n_pages, &total_pages) || total_pages > p->arg.max_pages) { + if (check_add_overflow(p->found_pages, n_pages, &total_pages) || + total_pages > p->arg.max_pages) { size_t n_too_much = total_pages - p->arg.max_pages; *end -= n_too_much * PAGE_SIZE; n_pages -= n_too_much; @@ -2012,6 +2017,7 @@ static int pagemap_scan_output(unsigned long categories, p->found_pages += n_pages; if (ret) p->end_addr = *end; + return ret; } @@ -2044,7 +2050,7 @@ static int pagemap_scan_thp_entry(pmd_t *pmd, unsigned long start, * Break huge page into small pages if the WP operation * need to be performed is on a portion of the huge page. */ - if (end != start + HPAGE_SIZE) { + if (end != start + HPAGE_SIZE || ret == -ENOSPC) { spin_unlock(ptl); split_huge_pmd(vma, pmd, start); pagemap_scan_backout_range(p, start, end); @@ -2066,8 +2072,8 @@ static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start, { struct pagemap_scan_private *p = walk->private; struct vm_area_struct *vma = walk->vma; + unsigned long addr, categories, next; pte_t *pte, *start_pte; - unsigned long addr; bool flush = false; spinlock_t *ptl; int ret; @@ -2088,12 +2094,14 @@ static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start, } for (addr = start; addr != end; pte++, addr += PAGE_SIZE) { - unsigned long categories = p->cur_vma_category | - pagemap_page_category(vma, addr, ptep_get(pte)); - unsigned long next = addr + PAGE_SIZE; + categories = p->cur_vma_category | + pagemap_page_category(vma, addr, ptep_get(pte)); + next = addr + PAGE_SIZE; ret = pagemap_scan_output(categories, p, addr, &next); - if (next == addr) + if (ret == 0 && next == addr) + continue; + else if (next == addr) break; if (~p->arg.flags & PM_SCAN_WP_MATCHING) @@ -2175,7 +2183,7 @@ static int pagemap_scan_pte_hole(unsigned long addr, unsigned long end, { struct pagemap_scan_private *p = walk->private; struct vm_area_struct *vma = walk->vma; - int ret; + int ret, err; if (!vma) return 0; @@ -2187,7 +2195,7 @@ static int pagemap_scan_pte_hole(unsigned long addr, unsigned long end, if (~p->arg.flags & PM_SCAN_WP_MATCHING) return ret; - int err = uffd_wp_range(vma, addr, end - addr, true); + err = uffd_wp_range(vma, addr, end - addr, true); if (err < 0) ret = err; @@ -2204,8 +2212,6 @@ static const struct mm_walk_ops pagemap_scan_ops = { static int pagemap_scan_get_args(struct pm_scan_arg *arg, unsigned long uarg) { - unsigned long start, end, vec; - if (copy_from_user(arg, (void __user *)uarg, sizeof(*arg))) return -EFAULT; @@ -2219,22 +2225,24 @@ static int pagemap_scan_get_args(struct pm_scan_arg *arg, arg->category_anyof_mask | arg->return_mask) & ~PM_SCAN_CATEGORIES) return -EINVAL; - start = untagged_addr((unsigned long)arg->start); - end = untagged_addr((unsigned long)arg->end); - vec = untagged_addr((unsigned long)arg->vec); + arg->start = untagged_addr((unsigned long)arg->start); + arg->end = untagged_addr((unsigned long)arg->end); + arg->vec = untagged_addr((unsigned long)arg->vec); /* Validate memory pointers */ - if (!IS_ALIGNED(start, PAGE_SIZE)) + if (!IS_ALIGNED(arg->start, PAGE_SIZE)) return -EINVAL; - if (!access_ok((void __user *)start, end - start)) + if (!access_ok((void __user *)arg->start, arg->end - arg->start)) return -EFAULT; - if (!vec && arg->vec_len) + if (!arg->vec && arg->vec_len) return -EFAULT; - if (vec && !access_ok((void __user *)vec, + if (arg->vec && !access_ok((void __user *)arg->vec, arg->vec_len * sizeof(struct page_region))) return -EFAULT; /* Fixup default values */ + arg->end = (arg->end & ~PAGE_MASK) ? + ((arg->end & PAGE_MASK) + PAGE_SIZE) : (arg->end); if (!arg->max_pages) arg->max_pages = ULONG_MAX; @@ -2279,7 +2287,7 @@ static int pagemap_scan_init_bounce_buffer(struct pagemap_scan_private *p) if (!p->vec_buf) return -ENOMEM; - p->vec_out = (void __user *)p->arg.vec; + p->vec_out = (struct page_region __user *)p->arg.vec; return 0; } -- 2.39.2