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=-7.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 299CCC433E4 for ; Thu, 16 Jul 2020 16:29:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E903D20739 for ; Thu, 16 Jul 2020 16:29:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E903D20739 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ubuntu.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 84A628D0025; Thu, 16 Jul 2020 12:29:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7D6E58D0005; Thu, 16 Jul 2020 12:29:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6281F8D0025; Thu, 16 Jul 2020 12:29:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0049.hostedemail.com [216.40.44.49]) by kanga.kvack.org (Postfix) with ESMTP id 41BE58D0005 for ; Thu, 16 Jul 2020 12:29:50 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id F01DA1EFF for ; Thu, 16 Jul 2020 16:29:49 +0000 (UTC) X-FDA: 77044475298.26.base03_5f0debf26f03 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin26.hostedemail.com (Postfix) with ESMTP id C595C1804B667 for ; Thu, 16 Jul 2020 16:29:49 +0000 (UTC) X-HE-Tag: base03_5f0debf26f03 X-Filterd-Recvd-Size: 3190 Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Thu, 16 Jul 2020 16:29:49 +0000 (UTC) Received: from ip5f5af08c.dynamic.kabel-deutschland.de ([95.90.240.140] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jw6lI-0001Zl-5G; Thu, 16 Jul 2020 16:29:32 +0000 Date: Thu, 16 Jul 2020 18:29:31 +0200 From: Christian Brauner To: Michal Hocko Cc: Tetsuo Handa , Greg Kroah-Hartman , Arve Hjonnevag , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , syzbot , acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, linux-kernel@vger.kernel.org, mark.rutland@arm.com, mingo@redhat.com, namhyung@kernel.org, peterz@infradead.org, syzkaller-bugs@googlegroups.com, "open list:ANDROID DRIVERS" , linux-mm Subject: Re: [PATCH v2] binder: Don't use mmput() from shrinker function. Message-ID: <20200716162931.g3delsp7qmfjup6x@wittgenstein> References: <0000000000001fbbb605aa805c9b@google.com> <5ce3ee90-333e-638d-ac8c-cd6d7ab7aa3b@I-love.SAKURA.ne.jp> <20200716083506.GA20915@dhcp22.suse.cz> <36db7016-98d6-2c6b-110b-b2481fd480ac@i-love.sakura.ne.jp> <20200716135445.GN31089@dhcp22.suse.cz> <4ba9adb2-43f5-2de0-22de-f6075c1fab50@i-love.sakura.ne.jp> <20200716151756.GO31089@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200716151756.GO31089@dhcp22.suse.cz> X-Rspamd-Queue-Id: C595C1804B667 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jul 16, 2020 at 05:17:56PM +0200, Michal Hocko wrote: > On Fri 17-07-20 00:12:15, Tetsuo Handa wrote: > > 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 Thanks for the careful review Michal! Does this need a Cc: stable? Otherwise Acked-by: Christian Brauner Thanks! Christian