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 X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E65E3C4360F for ; Fri, 8 Mar 2019 12:53:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9CE72085A for ; Fri, 8 Mar 2019 12:53:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552049636; bh=kAF+jAqt+Ux3Rqbawlym4fuWoWDe1mA5SH1So9tO2FU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=I6WIjbd96HwaIUjfp+bUHaMla5mSvJSE9FK9LzIdYpnP5oHnjDDaFrlBweSe/vj5n XU7T3gp/3pXAYHGQ8hQOXEpzPs3EY1aSql5yb+5usIDrDvUY0SPcTmEqE9VUmL1eGU KMD6buiDvhO0Z75Qv+lMa71YqvF1v/tYtojuMEvM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727242AbfCHMxz (ORCPT ); Fri, 8 Mar 2019 07:53:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:57568 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726898AbfCHMxx (ORCPT ); Fri, 8 Mar 2019 07:53:53 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C8EAF208E4; Fri, 8 Mar 2019 12:53:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552049632; bh=kAF+jAqt+Ux3Rqbawlym4fuWoWDe1mA5SH1So9tO2FU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MGW/E797Au/ZLj0ZIKyFHjfdWuoTQnm8s+seOM/Oz2jajTbXhvVSS5T/Lf6PstF3X 8WfhNveIQr57VQmWemyj/w3kLd9ULVn5eZfDLU+ylAz4mYZf9TpTQIAUsK4CDYnaLV Q3YUNMoBjl4tdOF9uh0kRl/QUh4tyDrs4Q1qO84I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , syzbot , syzbot , Tetsuo Handa , "Joel Fernandes (Google)" Subject: [PATCH 4.20 16/76] staging: android: ashmem: Dont call fallocate() with ashmem_mutex held. Date: Fri, 8 Mar 2019 13:49:28 +0100 Message-Id: <20190308124915.350067312@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190308124914.789210760@linuxfoundation.org> References: <20190308124914.789210760@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.20-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa commit fb4415a12632f0b9078a0aa80c16745d48fcfc74 upstream. syzbot is hitting lockdep warnings [1][2][3]. This patch tries to fix the warning by eliminating ashmem_shrink_scan() => {shmem|vfs}_fallocate() sequence. [1] https://syzkaller.appspot.com/bug?id=87c399f6fa6955006080b24142e2ce7680295ad4 [2] https://syzkaller.appspot.com/bug?id=7ebea492de7521048355fc84210220e1038a7908 [3] https://syzkaller.appspot.com/bug?id=e02419c12131c24e2a957ea050c2ab6dcbbc3270 Reported-by: syzbot Reported-by: syzbot Reported-by: syzbot Signed-off-by: Tetsuo Handa Cc: stable@vger.kernel.org Acked-by: Joel Fernandes (Google) Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ashmem.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -75,6 +75,9 @@ struct ashmem_range { /* LRU list of unpinned pages, protected by ashmem_mutex */ static LIST_HEAD(ashmem_lru_list); +static atomic_t ashmem_shrink_inflight = ATOMIC_INIT(0); +static DECLARE_WAIT_QUEUE_HEAD(ashmem_shrink_wait); + /* * long lru_count - The count of pages on our LRU list. * @@ -438,7 +441,6 @@ out: static unsigned long ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) { - struct ashmem_range *range, *next; unsigned long freed = 0; /* We might recurse into filesystem code, so bail out if necessary */ @@ -448,21 +450,33 @@ ashmem_shrink_scan(struct shrinker *shri if (!mutex_trylock(&ashmem_mutex)) return -1; - list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { + while (!list_empty(&ashmem_lru_list)) { + struct ashmem_range *range = + list_first_entry(&ashmem_lru_list, typeof(*range), lru); loff_t start = range->pgstart * PAGE_SIZE; loff_t end = (range->pgend + 1) * PAGE_SIZE; + struct file *f = range->asma->file; - range->asma->file->f_op->fallocate(range->asma->file, - FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, - start, end - start); + get_file(f); + atomic_inc(&ashmem_shrink_inflight); range->purged = ASHMEM_WAS_PURGED; lru_del(range); freed += range_size(range); + mutex_unlock(&ashmem_mutex); + f->f_op->fallocate(f, + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + start, end - start); + fput(f); + if (atomic_dec_and_test(&ashmem_shrink_inflight)) + wake_up_all(&ashmem_shrink_wait); + if (!mutex_trylock(&ashmem_mutex)) + goto out; if (--sc->nr_to_scan <= 0) break; } mutex_unlock(&ashmem_mutex); +out: return freed; } @@ -713,6 +727,7 @@ static int ashmem_pin_unpin(struct ashme return -EFAULT; mutex_lock(&ashmem_mutex); + wait_event(ashmem_shrink_wait, !atomic_read(&ashmem_shrink_inflight)); if (!asma->file) goto out_unlock;