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 3B440C7EE24 for ; Tue, 30 May 2023 19:44:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231422AbjE3ToA (ORCPT ); Tue, 30 May 2023 15:44:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34652 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231428AbjE3Tn6 (ORCPT ); Tue, 30 May 2023 15:43:58 -0400 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F624115 for ; Tue, 30 May 2023 12:43:56 -0700 (PDT) Received: by mail-pg1-x54a.google.com with SMTP id 41be03b00d2f7-53f06f7cc74so84603a12.1 for ; Tue, 30 May 2023 12:43:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685475836; x=1688067836; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=ftH1i7B4bHzPdsjKfJA4nT7vTkwk7yoT+/tju1GrDD8=; b=g9fz4kTXgwXrM7gXjsxE9AhrV5T8QPVst4BCk23Qonj+F5vw+8LuFh70SInxDWcqUF P04/GEUcKLW214WNMMqrlLMPDIGOF1Iex/icGyNXYY187CTTHSf+F6gTI5CmOC7AwXiC rjMpycNGOrBwb8YJWo2IIRX4rXnmy+W1n241MtdjxzbpuHa3D28PFJGtA+T3R3n0Ayrp V1HmZ92Ai/Y1g8v5HmjL4cy0I+i+y7ZHAhi1s05oJL1ncmu/ndLjh+4Vsc988NC7NJzU I4kvio0IY4QJH+hoVlLm1X+kYSoqMEW70L0s/UiuwYMHXO78qHSuE31Hr/nyae3mYkeW QJGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685475836; x=1688067836; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ftH1i7B4bHzPdsjKfJA4nT7vTkwk7yoT+/tju1GrDD8=; b=W7q1tkZNYyMHljUUHJIdTtNTQ53Cu5R2JiAjggVGDMph8NcZLBVTzgZncHt1LUwLej lG5JEEBgHnX8v5cTNYWtHyVHTYdAvLwCP+/TgiwxiG5GjF3yrkqZlxCs11D1hBgUY9yG Q0IasyEOkXlTC0eaaWZmkMZGU3Ax5yFWR6dranhvXaccoaK4xTMrcyNh0932N3dYF7R8 trCvG/2YpPkxKY9DwmbxBLid7xbxWP/8H79eRgsTyeT/SMqQaiAY8pRlEtOi39oDFkJ+ l2ifd+ENzZgDr9YlYgn+YYw9coarmO3RfQee/QtyemddrSUjgHOoiUeT87LMROWiUErZ jr+A== X-Gm-Message-State: AC+VfDz8QruE3Ds+w+z9NIqhAl2LFBmichdIHl9o8QyHclPRXh6tAuKw JBcwD6tTWABJtmHDC3QlDcQ4ttBBkEvVzOH8YnwQAlTK39bH+DP+scvuoi9IvZvQYXITYb9c6Go dE/qogLxHPnCXiftkxHxdub1I8y55knr7DTWNU7jUmH10shwLggDScmPIEYsHe8uS+pM= X-Google-Smtp-Source: ACHHUZ6sUtgEd7Xk0iH6q7d8WXbnMO+Ov/W+QbpksRyx30Lpy2ITwwqjd7bQwnMt6l39+2dySK25ZgLu6RI5qg== X-Received: from xllamas.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5070]) (user=cmllamas job=sendgmr) by 2002:a65:45c1:0:b0:52c:4e3e:24ef with SMTP id m1-20020a6545c1000000b0052c4e3e24efmr734630pgr.2.1685475835954; Tue, 30 May 2023 12:43:55 -0700 (PDT) Date: Tue, 30 May 2023 19:43:36 +0000 In-Reply-To: <20230530194338.1683009-1-cmllamas@google.com> Mime-Version: 1.0 References: <20230530194338.1683009-1-cmllamas@google.com> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Message-ID: <20230530194338.1683009-3-cmllamas@google.com> Subject: [PATCH 5.15.y 3/5] Revert "android: binder: stop saving a pointer to the VMA" From: Carlos Llamas To: stable@vger.kernel.org Cc: Carlos Llamas , Liam Howlett , Suren Baghdasaryan , Greg Kroah-Hartman Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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 [cmllamas: fixed merge conflict in binder_alloc_set_vma()] Signed-off-by: Carlos Llamas --- drivers/android/binder_alloc.c | 27 ++++++++++++------------- drivers/android/binder_alloc.h | 2 +- drivers/android/binder_alloc_selftest.c | 2 +- 3 files changed, 15 insertions(+), 16 deletions(-) diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index f1dc5326a1d9..3cfad638db63 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -213,7 +213,7 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate, if (mm) { mmap_read_lock(mm); - vma = vma_lookup(mm, alloc->vma_addr); + vma = alloc->vma; } if (!vma && need_mm) { @@ -313,14 +313,12 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate, static inline void binder_alloc_set_vma(struct binder_alloc *alloc, struct vm_area_struct *vma) { - unsigned long vm_start = 0; - - if (vma) { - vm_start = vma->vm_start; - mmap_assert_write_locked(alloc->vma_vm_mm); - } - - alloc->vma_addr = vm_start; + /* + * If we see alloc->vma is not NULL, buffer data structures set up + * completely. Look at smp_rmb side binder_alloc_get_vma. + */ + smp_wmb(); + alloc->vma = vma; } static inline struct vm_area_struct *binder_alloc_get_vma( @@ -328,9 +326,11 @@ static inline struct vm_area_struct *binder_alloc_get_vma( { struct vm_area_struct *vma = NULL; - if (alloc->vma_addr) - vma = vma_lookup(alloc->vma_vm_mm, alloc->vma_addr); - + if (alloc->vma) { + /* Look at description in binder_alloc_set_vma */ + smp_rmb(); + vma = alloc->vma; + } return vma; } @@ -819,8 +819,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc) buffers = 0; mutex_lock(&alloc->mutex); - BUG_ON(alloc->vma_addr && - vma_lookup(alloc->vma_vm_mm, alloc->vma_addr)); + BUG_ON(alloc->vma); while ((n = rb_first(&alloc->allocated_buffers))) { buffer = rb_entry(n, struct binder_buffer, rb_node); diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h index 1e4fd37af5e0..7dea57a84c79 100644 --- a/drivers/android/binder_alloc.h +++ b/drivers/android/binder_alloc.h @@ -100,7 +100,7 @@ struct binder_lru_page { */ struct binder_alloc { struct mutex mutex; - unsigned long vma_addr; + struct vm_area_struct *vma; struct mm_struct *vma_vm_mm; void __user *buffer; struct list_head buffers; diff --git a/drivers/android/binder_alloc_selftest.c b/drivers/android/binder_alloc_selftest.c index 43a881073a42..c2b323bc3b3a 100644 --- a/drivers/android/binder_alloc_selftest.c +++ b/drivers/android/binder_alloc_selftest.c @@ -287,7 +287,7 @@ void binder_selftest_alloc(struct binder_alloc *alloc) 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); -- 2.41.0.rc0.172.g3f132b7071-goog