From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5206113A3F2 for ; Wed, 6 Aug 2025 22:54:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754520842; cv=none; b=V0jljuTJ3EiUNm8xVuuRdgbzwLw0/jEMjqhpgrOZs6D8KRWNjJrLPEt8x+pXR0EG6ESdvBXinU1nrmG+E9d/SXd3blQfcGiDWxbU0+V6+1CUwSbCTPp19kr9Wz5ze5dwsHhVEfbLIbn/OwGi/q85+vmpyTgXVtxFoQDTA0dkBWk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754520842; c=relaxed/simple; bh=ZCTL544nF7H9ikKMppzfzAGCWRFKwFZMz9WkbSx7UOg=; h=Date:To:From:Subject:Message-Id; b=PJuf44j536WtrSSxgVeKnKAN+CIsVINvUxx5yRF9Yf1B0QYXXw2XMpdZEs2DUxGnPWbkSbSeSJa5UC3kp35WJZ+O1/mSBnyu0uaGxTzsIgi0iIaFoi6lM5NF3JxREU0Di4mfs2W7BvPNbaOYsGJ0hjMygQcqnjpx1zJpfoSnrgs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=XtHvXEZ9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="XtHvXEZ9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2157C4CEE7; Wed, 6 Aug 2025 22:54:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1754520841; bh=ZCTL544nF7H9ikKMppzfzAGCWRFKwFZMz9WkbSx7UOg=; h=Date:To:From:Subject:From; b=XtHvXEZ9leMFiuIAS7KFeFVhlgzaZtep2fiJjSkt9+eCb8ODstMr6lvom50R1SFw3 SLoElqLOmmQcMKR0vG8+hJ0qPU/NNJQ6MmDFoOq4oo0apUMbMdLlWRE8bT4b54PR9V B9aaTKYxlHH066v1EBqYb8lhKPAKgjbJPqYzzm0M= Date: Wed, 06 Aug 2025 15:54:01 -0700 To: mm-commits@vger.kernel.org,v-songbaohua@oppo.com,surenb@google.com,peterx@redhat.com,kaleshsingh@google.com,david@redhat.com,lokeshgidra@google.com,akpm@linux-foundation.org From: Andrew Morton Subject: [failures] userfaultfd-opportunistic-tlb-flush-batching-for-present-pages-in-move.patch removed from -mm tree Message-Id: <20250806225401.C2157C4CEE7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: userfaultfd: opportunistic TLB-flush batching for present pages in MOVE has been removed from the -mm tree. Its filename was userfaultfd-opportunistic-tlb-flush-batching-for-present-pages-in-move.patch This patch was dropped because it had testing failures ------------------------------------------------------ From: Lokesh Gidra Subject: userfaultfd: opportunistic TLB-flush batching for present pages in MOVE Date: Tue, 5 Aug 2025 05:14:10 -0700 MOVE ioctl's runtime is dominated by TLB-flush cost, which is required for moving present pages. Mitigate this cost by opportunistically batching present contiguous pages for TLB flushing. Without batching, in our testing on an arm64 Android device with UFFD GC, which uses MOVE ioctl for compaction, we observed that out of the total time spent in move_pages_pte(), over 40% is in ptep_clear_flush(), and ~20% in vm_normal_folio(). With batching, the proportion of vm_normal_folio() increases to over 70% of move_pages_pte() without any changes to vm_normal_folio(). Furthermore, time spent within move_pages_pte() is only ~20%, which includes TLB-flush overhead. Link: https://lkml.kernel.org/r/20250805121410.1658418-1-lokeshgidra@google.com Signed-off-by: Lokesh Gidra Cc: Suren Baghdasaryan Cc: Kalesh Singh Cc: Barry Song Cc: David Hildenbrand Cc: Peter Xu Signed-off-by: Andrew Morton --- mm/userfaultfd.c | 169 +++++++++++++++++++++++++++++++-------------- 1 file changed, 118 insertions(+), 51 deletions(-) --- a/mm/userfaultfd.c~userfaultfd-opportunistic-tlb-flush-batching-for-present-pages-in-move +++ a/mm/userfaultfd.c @@ -1026,18 +1026,61 @@ static inline bool is_pte_pages_stable(p pmd_same(dst_pmdval, pmdp_get_lockless(dst_pmd)); } -static int move_present_pte(struct mm_struct *mm, - struct vm_area_struct *dst_vma, - struct vm_area_struct *src_vma, - unsigned long dst_addr, unsigned long src_addr, - pte_t *dst_pte, pte_t *src_pte, - pte_t orig_dst_pte, pte_t orig_src_pte, - pmd_t *dst_pmd, pmd_t dst_pmdval, - spinlock_t *dst_ptl, spinlock_t *src_ptl, - struct folio *src_folio) +/* + * Checks if the two ptes and the corresponding folio are eligible for batched + * move. If so, then returns pointer to the folio, after locking it. Otherwise, + * returns NULL. + */ +static struct folio *check_ptes_for_batched_move(struct vm_area_struct *src_vma, + unsigned long src_addr, + pte_t *src_pte, pte_t *dst_pte) +{ + pte_t orig_dst_pte, orig_src_pte; + struct folio *folio; + + orig_dst_pte = ptep_get(dst_pte); + if (!pte_none(orig_dst_pte)) + return NULL; + + orig_src_pte = ptep_get(src_pte); + if (pte_none(orig_src_pte) || !pte_present(orig_src_pte) || + is_zero_pfn(pte_pfn(orig_src_pte))) + return NULL; + + folio = vm_normal_folio(src_vma, src_addr, orig_src_pte); + if (!folio || !folio_trylock(folio)) + return NULL; + if (!PageAnonExclusive(&folio->page) || folio_test_large(folio)) { + folio_unlock(folio); + return NULL; + } + return folio; +} + +static long move_present_ptes(struct mm_struct *mm, + struct vm_area_struct *dst_vma, + struct vm_area_struct *src_vma, + unsigned long dst_addr, unsigned long src_addr, + pte_t *dst_pte, pte_t *src_pte, + pte_t orig_dst_pte, pte_t orig_src_pte, + pmd_t *dst_pmd, pmd_t dst_pmdval, + spinlock_t *dst_ptl, spinlock_t *src_ptl, + struct folio *src_folio, unsigned long len) { int err = 0; + unsigned long src_start = src_addr; + unsigned long addr_end; + if (len > PAGE_SIZE) { + addr_end = (dst_addr + PMD_SIZE) & PMD_MASK; + if (dst_addr + len > addr_end) + len = addr_end - dst_addr; + + addr_end = (src_addr + PMD_SIZE) & PMD_MASK; + if (src_addr + len > addr_end) + len = addr_end - src_addr; + } + flush_cache_range(src_vma, src_addr, src_addr + len); double_pt_lock(dst_ptl, src_ptl); if (!is_pte_pages_stable(dst_pte, src_pte, orig_dst_pte, orig_src_pte, @@ -1051,31 +1094,53 @@ static int move_present_pte(struct mm_st err = -EBUSY; goto out; } + arch_enter_lazy_mmu_mode(); - orig_src_pte = ptep_clear_flush(src_vma, src_addr, src_pte); - /* Folio got pinned from under us. Put it back and fail the move. */ - if (folio_maybe_dma_pinned(src_folio)) { - set_pte_at(mm, src_addr, src_pte, orig_src_pte); - err = -EBUSY; - goto out; - } + addr_end = src_start + len; + while (true) { + orig_src_pte = ptep_get_and_clear(mm, src_addr, src_pte); + /* Folio got pinned from under us. Put it back and fail the move. */ + if (folio_maybe_dma_pinned(src_folio)) { + set_pte_at(mm, src_addr, src_pte, orig_src_pte); + err = -EBUSY; + break; + } - folio_move_anon_rmap(src_folio, dst_vma); - src_folio->index = linear_page_index(dst_vma, dst_addr); + folio_move_anon_rmap(src_folio, dst_vma); + src_folio->index = linear_page_index(dst_vma, dst_addr); - orig_dst_pte = folio_mk_pte(src_folio, dst_vma->vm_page_prot); - /* Set soft dirty bit so userspace can notice the pte was moved */ + orig_dst_pte = folio_mk_pte(src_folio, dst_vma->vm_page_prot); + /* Set soft dirty bit so userspace can notice the pte was moved */ #ifdef CONFIG_MEM_SOFT_DIRTY - orig_dst_pte = pte_mksoft_dirty(orig_dst_pte); + orig_dst_pte = pte_mksoft_dirty(orig_dst_pte); #endif - if (pte_dirty(orig_src_pte)) - orig_dst_pte = pte_mkdirty(orig_dst_pte); - orig_dst_pte = pte_mkwrite(orig_dst_pte, dst_vma); + if (pte_dirty(orig_src_pte)) + orig_dst_pte = pte_mkdirty(orig_dst_pte); + orig_dst_pte = pte_mkwrite(orig_dst_pte, dst_vma); + set_pte_at(mm, dst_addr, dst_pte, orig_dst_pte); + + src_addr += PAGE_SIZE; + if (src_addr == addr_end) + break; + src_pte++; + dst_pte++; + + folio_unlock(src_folio); + src_folio = check_ptes_for_batched_move(src_vma, src_addr, src_pte, dst_pte); + if (!src_folio) + break; + dst_addr += PAGE_SIZE; + } + + arch_leave_lazy_mmu_mode(); + if (src_addr > src_start) + flush_tlb_range(src_vma, src_start, src_addr); - set_pte_at(mm, dst_addr, dst_pte, orig_dst_pte); out: double_pt_unlock(dst_ptl, src_ptl); - return err; + if (src_folio) + folio_unlock(src_folio); + return src_addr > src_start ? src_addr - src_start : err; } static int move_swap_pte(struct mm_struct *mm, struct vm_area_struct *dst_vma, @@ -1140,7 +1205,7 @@ static int move_swap_pte(struct mm_struc set_pte_at(mm, dst_addr, dst_pte, orig_src_pte); double_pt_unlock(dst_ptl, src_ptl); - return 0; + return PAGE_SIZE; } static int move_zeropage_pte(struct mm_struct *mm, @@ -1154,6 +1219,7 @@ static int move_zeropage_pte(struct mm_s { pte_t zero_pte; + flush_cache_range(src_vma, src_addr, src_addr + PAGE_SIZE); double_pt_lock(dst_ptl, src_ptl); if (!is_pte_pages_stable(dst_pte, src_pte, orig_dst_pte, orig_src_pte, dst_pmd, dst_pmdval)) { @@ -1167,20 +1233,19 @@ static int move_zeropage_pte(struct mm_s set_pte_at(mm, dst_addr, dst_pte, zero_pte); double_pt_unlock(dst_ptl, src_ptl); - return 0; + return PAGE_SIZE; } /* - * The mmap_lock for reading is held by the caller. Just move the page - * from src_pmd to dst_pmd if possible, and return true if succeeded - * in moving the page. + * The mmap_lock for reading is held by the caller. Just move the page(s) + * from src_pmd to dst_pmd if possible, and return number of bytes moved. */ -static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, - struct vm_area_struct *dst_vma, - struct vm_area_struct *src_vma, - unsigned long dst_addr, unsigned long src_addr, - __u64 mode) +static long move_pages_ptes(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, + struct vm_area_struct *dst_vma, + struct vm_area_struct *src_vma, + unsigned long dst_addr, unsigned long src_addr, + unsigned long len, __u64 mode) { swp_entry_t entry; struct swap_info_struct *si = NULL; @@ -1196,9 +1261,8 @@ static int move_pages_pte(struct mm_stru struct mmu_notifier_range range; int err = 0; - flush_cache_range(src_vma, src_addr, src_addr + PAGE_SIZE); mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, - src_addr, src_addr + PAGE_SIZE); + src_addr, src_addr + len); mmu_notifier_invalidate_range_start(&range); retry: /* @@ -1257,7 +1321,7 @@ retry: if (!(mode & UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES)) err = -ENOENT; else /* nothing to do to move a hole */ - err = 0; + err = PAGE_SIZE; goto out; } @@ -1375,10 +1439,13 @@ retry: } } - err = move_present_pte(mm, dst_vma, src_vma, - dst_addr, src_addr, dst_pte, src_pte, - orig_dst_pte, orig_src_pte, dst_pmd, - dst_pmdval, dst_ptl, src_ptl, src_folio); + err = move_present_ptes(mm, dst_vma, src_vma, + dst_addr, src_addr, dst_pte, src_pte, + orig_dst_pte, orig_src_pte, dst_pmd, + dst_pmdval, dst_ptl, src_ptl, src_folio, len); + /* folio is already unlocked by move_present_ptes() */ + folio_put(src_folio); + src_folio = NULL; } else { struct folio *folio = NULL; @@ -1737,7 +1804,7 @@ ssize_t move_pages(struct userfaultfd_ct { struct mm_struct *mm = ctx->mm; struct vm_area_struct *src_vma, *dst_vma; - unsigned long src_addr, dst_addr; + unsigned long src_addr, dst_addr, src_end; pmd_t *src_pmd, *dst_pmd; long err = -EINVAL; ssize_t moved = 0; @@ -1780,8 +1847,8 @@ ssize_t move_pages(struct userfaultfd_ct if (err) goto out_unlock; - for (src_addr = src_start, dst_addr = dst_start; - src_addr < src_start + len;) { + for (src_addr = src_start, dst_addr = dst_start, src_end = src_start + len; + src_addr < src_end;) { spinlock_t *ptl; pmd_t dst_pmdval; unsigned long step_size; @@ -1862,10 +1929,10 @@ ssize_t move_pages(struct userfaultfd_ct break; } - err = move_pages_pte(mm, dst_pmd, src_pmd, - dst_vma, src_vma, - dst_addr, src_addr, mode); - step_size = PAGE_SIZE; + err = move_pages_ptes(mm, dst_pmd, src_pmd, + dst_vma, src_vma, dst_addr, + src_addr, src_end - src_addr, mode); + step_size = err; } cond_resched(); @@ -1877,7 +1944,7 @@ ssize_t move_pages(struct userfaultfd_ct break; } - if (err) { + if (err < 0) { if (err == -EAGAIN) continue; break; _ Patches currently in -mm which might be from lokeshgidra@google.com are