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 DE247C77B7E for ; Sun, 28 May 2023 19:36:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230416AbjE1Tgz (ORCPT ); Sun, 28 May 2023 15:36:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230417AbjE1Tgx (ORCPT ); Sun, 28 May 2023 15:36:53 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71502DC for ; Sun, 28 May 2023 12:36:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0ED2C61E52 for ; Sun, 28 May 2023 19:36:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BDE7C433D2; Sun, 28 May 2023 19:36:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685302611; bh=rtSK500I63Shf+BP5KyddA4A75N3rORTgN+WI4SjmvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MwT1E5ckVYcbPl4iIsXtDyryARF4oW8qNxdLwViTxBNwgJc5BojXERqlzxfKCFae1 O5n2Fq1MGGTCmYVv5XdOw+JyiNL3kG37K+Hml+OTDKfQcoAJbdVFBH01mpUG2nSENX P55rX+TNItxa5iE/U+quYx+H+YZ8vpAsH+ilwuhQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Liam Howlett , Suren Baghdasaryan , Carlos Llamas Subject: [PATCH 6.1 046/119] Revert "android: binder: stop saving a pointer to the VMA" Date: Sun, 28 May 2023 20:10:46 +0100 Message-Id: <20230528190836.918701923@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230528190835.386670951@linuxfoundation.org> References: <20230528190835.386670951@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Carlos Llamas commit c0fd2101781ef761b636769b2f445351f71c3626 upstream. This reverts commit a43cfc87caaf46710c8027a8c23b8a55f1078f19. This patch fixed an issue reported by syzkaller in [1]. However, this turned out to be only a band-aid in binder. The root cause, as bisected by syzkaller, was fixed by commit 5789151e48ac ("mm/mmap: undo ->mmap() when mas_preallocate() fails"). We no longer need the patch for binder. Reverting such patch allows us to have a lockless access to alloc->vma in specific cases where the mmap_lock is not required. This approach avoids the contention that caused a performance regression. [1] https://lore.kernel.org/all/0000000000004a0dbe05e1d749e0@google.com [cmllamas: resolved conflicts with rework of alloc->mm and removal of binder_alloc_set_vma() also fixed comment section] Fixes: a43cfc87caaf ("android: binder: stop saving a pointer to the VMA") Cc: Liam Howlett Cc: Suren Baghdasaryan Cc: stable@vger.kernel.org Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20230502201220.1756319-2-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.c | 17 +++++++++-------- drivers/android/binder_alloc.h | 4 ++-- drivers/android/binder_alloc_selftest.c | 2 +- 3 files changed, 12 insertions(+), 11 deletions(-) --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -213,7 +213,7 @@ static int binder_update_page_range(stru if (mm) { mmap_read_lock(mm); - vma = vma_lookup(mm, alloc->vma_addr); + vma = alloc->vma; } if (!vma && need_mm) { @@ -314,9 +314,11 @@ static inline struct vm_area_struct *bin { struct vm_area_struct *vma = NULL; - if (alloc->vma_addr) - vma = vma_lookup(alloc->mm, alloc->vma_addr); - + if (alloc->vma) { + /* Look at description in binder_alloc_set_vma */ + smp_rmb(); + vma = alloc->vma; + } return vma; } @@ -775,7 +777,7 @@ int binder_alloc_mmap_handler(struct bin buffer->free = 1; binder_insert_free_buffer(alloc, buffer); alloc->free_async_space = alloc->buffer_size / 2; - alloc->vma_addr = vma->vm_start; + alloc->vma = vma; return 0; @@ -805,8 +807,7 @@ void binder_alloc_deferred_release(struc buffers = 0; mutex_lock(&alloc->mutex); - BUG_ON(alloc->vma_addr && - vma_lookup(alloc->mm, alloc->vma_addr)); + BUG_ON(alloc->vma); while ((n = rb_first(&alloc->allocated_buffers))) { buffer = rb_entry(n, struct binder_buffer, rb_node); @@ -958,7 +959,7 @@ int binder_alloc_get_allocated_count(str */ void binder_alloc_vma_close(struct binder_alloc *alloc) { - alloc->vma_addr = 0; + alloc->vma = 0; } /** --- a/drivers/android/binder_alloc.h +++ b/drivers/android/binder_alloc.h @@ -75,7 +75,7 @@ struct binder_lru_page { /** * struct binder_alloc - per-binder proc state for binder allocator * @mutex: protects binder_alloc fields - * @vma_addr: vm_area_struct->vm_start passed to mmap_handler + * @vma: vm_area_struct passed to mmap_handler * (invariant after mmap) * @mm: copy of task->mm (invariant after open) * @buffer: base of per-proc address space mapped via mmap @@ -99,7 +99,7 @@ struct binder_lru_page { */ struct binder_alloc { struct mutex mutex; - unsigned long vma_addr; + struct vm_area_struct *vma; struct mm_struct *mm; void __user *buffer; struct list_head buffers; --- a/drivers/android/binder_alloc_selftest.c +++ b/drivers/android/binder_alloc_selftest.c @@ -287,7 +287,7 @@ void binder_selftest_alloc(struct binder if (!binder_selftest_run) return; mutex_lock(&binder_selftest_lock); - if (!binder_selftest_run || !alloc->vma_addr) + if (!binder_selftest_run || !alloc->vma) goto done; pr_info("STARTED\n"); binder_selftest_alloc_offset(alloc, end_offset, 0);