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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 0FC98C433F2 for ; Mon, 27 Jul 2020 14:11:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D710F21744 for ; Mon, 27 Jul 2020 14:11:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595859100; bh=QZVW5a1aE5FbLe9+ltNBnDpgn0AHKSmS9TQ8jjloP9U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=f0eMftzklN/vrivRYQqmDfNthjNaWhzeRJVfrkfEC31A9ZUqbcwazL3SSbKmT8ybp oL1WrILlaUadZDW03AcVMQ5Yptkm+K1VoESZS8eiuqOi8KeHi8ONkFbkS5gEZU40D/ AFt1jMjleJGzusdq1vlwBk7qJ3KBYqnHnvYBEoms= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730037AbgG0OLf (ORCPT ); Mon, 27 Jul 2020 10:11:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:35174 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730026AbgG0OLc (ORCPT ); Mon, 27 Jul 2020 10:11:32 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 4237420838; Mon, 27 Jul 2020 14:11:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595859091; bh=QZVW5a1aE5FbLe9+ltNBnDpgn0AHKSmS9TQ8jjloP9U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aqbg/9CRN6SWcZKc0KIWyr90rWj0QkFlm7ctQyUn4omFGgVEs83RS/AyrVXUaEkYE kBHwR1YylpzMRp6ezTz5jMdGd6Yh54WzSR05rqs1PAF7vZceV/B13mgQ+xR0RPuCck Q+5xWAYFr3AYws7eDQG7xBspZaEs0K9Nm9b8wZhU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , syzbot , Tetsuo Handa , Michal Hocko , Todd Kjos , Christian Brauner Subject: [PATCH 4.19 61/86] binder: Dont use mmput() from shrinker function. Date: Mon, 27 Jul 2020 16:04:35 +0200 Message-Id: <20200727134917.494599997@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200727134914.312934924@linuxfoundation.org> References: <20200727134914.312934924@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Tetsuo Handa commit f867c771f98891841c217fa8459244ed0dd28921 upstream. syzbot is reporting that mmput() from shrinker function has a risk of deadlock [1], for delayed_uprobe_add() from update_ref_ctr() calls kzalloc(GFP_KERNEL) with delayed_uprobe_lock held, and uprobe_clear_state() from __mmput() also holds delayed_uprobe_lock. Commit a1b2289cef92ef0e ("android: binder: drop lru lock in isolate callback") replaced mmput() with mmput_async() in order to avoid sleeping with spinlock held. But this patch replaces mmput() with mmput_async() in order not to start __mmput() from shrinker context. [1] https://syzkaller.appspot.com/bug?id=bc9e7303f537c41b2b0cc2dfcea3fc42964c2d45 Reported-by: syzbot Reported-by: syzbot Signed-off-by: Tetsuo Handa Reviewed-by: Michal Hocko Acked-by: Todd Kjos Acked-by: Christian Brauner Cc: stable Link: https://lore.kernel.org/r/4ba9adb2-43f5-2de0-22de-f6075c1fab50@i-love.sakura.ne.jp Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -987,7 +987,7 @@ enum lru_status binder_alloc_free_page(s trace_binder_unmap_user_end(alloc, index); } up_read(&mm->mmap_sem); - mmput(mm); + mmput_async(mm); trace_binder_unmap_kernel_start(alloc, index);