From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16155C001DF for ; Mon, 24 Jul 2023 19:00:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230050AbjGXS77 (ORCPT ); Mon, 24 Jul 2023 14:59:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230128AbjGXS75 (ORCPT ); Mon, 24 Jul 2023 14:59:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1589610F5 for ; Mon, 24 Jul 2023 11:59:46 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 90A77613CA for ; Mon, 24 Jul 2023 18:59:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D069EC433C7; Mon, 24 Jul 2023 18:59:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1690225185; bh=cRy4xzNLt56eft0RZOCe+2slhmGpBRgZx30rgYbrSzs=; h=Date:To:From:Subject:From; b=xP/P46v6cMpXU5c4OqwsqXTdGfavV4I2xeSjM/NmUbPJmBkvoJBzzi9qSDZtnS30c NEqYWoYpbL8TcmzR+2bCtpV02SwPcqh6MGLJ6/0UQ+C1a18SH2s6Z/FyDWXIkvu4y0 XC4lF/W2zhdbU1vmY8WEetF0K9GKx5N/6kbcMlpc= Date: Mon, 24 Jul 2023 11:59:45 -0700 To: mm-commits@vger.kernel.org, zhangpeng.00@bytedance.com, surenb@google.com, Liam.Howlett@oracle.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-mmap-change-vma-iteration-order-in-do_vmi_align_munmap.patch added to mm-unstable branch Message-Id: <20230724185945.D069EC433C7@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/mmap: change vma iteration order in do_vmi_align_munmap() has been added to the -mm mm-unstable branch. Its filename is mm-mmap-change-vma-iteration-order-in-do_vmi_align_munmap.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-change-vma-iteration-order-in-do_vmi_align_munmap.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Liam R. Howlett" Subject: mm/mmap: change vma iteration order in do_vmi_align_munmap() Date: Mon, 24 Jul 2023 14:31:57 -0400 By delaying the setting of prev/next VMA until after the write of NULL, the probability of the prev/next VMA already being in the CPU cache is significantly increased, especially for larger munmap operations. It also means that prev/next will be loaded closer to when they are used. This requires changing the loop type when gathering the VMAs that will be freed. Since prev will be set later in the function, it is better to reverse the splitting direction of the start VMA (modify the new_below argument to __split_vma). Using the vma_iter_prev_range() to walk back to the correct location in the tree will, on the most part, mean walking within the CPU cache. Usually, this is two steps vs a node reset and a tree re-walk. Link: https://lkml.kernel.org/r/20230724183157.3939892-16-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Peng Zhang Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- mm/mmap.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) --- a/mm/mmap.c~mm-mmap-change-vma-iteration-order-in-do_vmi_align_munmap +++ a/mm/mmap.c @@ -2452,20 +2452,17 @@ do_vmi_align_munmap(struct vma_iterator if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) goto map_count_exceeded; - error = __split_vma(vmi, vma, start, 0); + error = __split_vma(vmi, vma, start, 1); if (error) goto start_split_failed; - - vma = vma_iter_load(vmi); } - prev = vma_prev(vmi); - /* * Detach a range of VMAs from the mm. Using next as a temp variable as * it is always overwritten. */ - for_each_vma_range(*vmi, next, end) { + next = vma; + do { /* Does it split the end? */ if (next->vm_end > end) { error = __split_vma(vmi, next, end, 0); @@ -2501,13 +2498,7 @@ do_vmi_align_munmap(struct vma_iterator BUG_ON(next->vm_start < start); BUG_ON(next->vm_start > end); #endif - } - - if (vma_iter_end(vmi) > end) - next = vma_iter_load(vmi); - - if (!next) - next = vma_next(vmi); + } for_each_vma_range(*vmi, next, end); #if defined(CONFIG_DEBUG_VM_MAPLE_TREE) /* Make sure no VMAs are about to be lost. */ @@ -2528,7 +2519,10 @@ do_vmi_align_munmap(struct vma_iterator BUG_ON(count != test_count); } #endif - vma_iter_set(vmi, start); + + while (vma_iter_addr(vmi) > start) + vma_iter_prev_range(vmi); + error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL); if (error) goto clear_tree_failed; @@ -2539,6 +2533,11 @@ do_vmi_align_munmap(struct vma_iterator if (unlock) mmap_write_downgrade(mm); + prev = vma_iter_prev_range(vmi); + next = vma_next(vmi); + if (next) + vma_iter_prev_range(vmi); + /* * We can free page tables without write-locking mmap_lock because VMAs * were isolated before we downgraded mmap_lock. _ Patches currently in -mm which might be from Liam.Howlett@oracle.com are mm-mmap-clean-up-validate_mm-calls.patch maple_tree-relax-lockdep-checks-for-on-stack-trees.patch mm-mmap-change-detached-vma-locking-scheme.patch maple_tree-be-more-strict-about-locking.patch maple_tree-add-benchmarking-for-mas_for_each.patch maple_tree-add-benchmarking-for-mas_prev.patch mm-change-do_vmi_align_munmap-tracking-of-vmas-to-remove.patch mm-remove-prev-check-from-do_vmi_align_munmap.patch maple_tree-introduce-__mas_set_range.patch mm-remove-re-walk-from-mmap_region.patch maple_tree-re-introduce-entry-to-mas_preallocate-arguments.patch maple_tree-adjust-node-allocation-on-mas_rebalance.patch mm-use-vma_iter_clear_gfp-in-nommu.patch mm-set-up-vma-iterator-for-vma_iter_prealloc-calls.patch maple_tree-move-mas_wr_end_piv-below-mas_wr_extend_null.patch maple_tree-update-mas_preallocate-testing.patch maple_tree-refine-mas_preallocate-node-calculations.patch maple_tree-reduce-resets-during-store-setup.patch mm-mmap-change-vma-iteration-order-in-do_vmi_align_munmap.patch