Received: by 2002:a25:e74b:0:0:0:0:0 with SMTP id e72csp1455910ybh; Mon, 13 Jul 2020 20:41:56 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwRdG+Lko2ywOYc8Lpd2ODaY/ocW0Lu+tek40b8XoKOlOTRCFv1dMNhCT5yvH0plbJT9hLa X-Received: by 2002:a50:ab5c:: with SMTP id t28mr2421658edc.209.1594698116068; Mon, 13 Jul 2020 20:41:56 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1594698116; cv=none; d=google.com; s=arc-20160816; b=dOLJ+4hqZF8nTODfpzXWI08M2bSH51IDP6zTfHWvWuC11oZKg5BRzNaf1wP0+wyvDr AEMvqaC0AS27ZvRXy7Rn9SMeIyKdXGE8+tJ4gkP9/XJZG/mDh3pX8fGhQGrtHGsgIoA1 WAk89IxJ67lmqB9pAEs7FJJ3y0vJY9HAWWRce1meoEVlx71xJuGdPTUyw7dRaEc536yW 2tvnY6Hn/c6jBlFVVJmkJC1YpZ5MabmKPeGXmdsk3iGt3W7fAacQ+xOcuq7JyNgCer8K m7TSTQUxQp5kPmD7/6ksncLqBArUtY/OHMwO9NahDxa3EO+Ue2X3u211Z/xCOYvnG7cW NZQg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:in-reply-to:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :dkim-signature; bh=+uRuQhCHlIKS8lRLca0ic0QI/Q8cDiMrC7aFPShku+U=; b=GeHWIGp99Dqv1RfV0PGAUdDq+iz7vXSOpjssCead2HoADq9ow5Muo+8UW8wWUPgd/y /WyrDMTDLoFg5yP3rXVglr1sld5wEvE6jk+wXKrg7UzUjQSWnzEA43OlebSYc9GWGrXy nA1lUSyG76oVYZv7Lyl2EDt6X+d08YvV5fpbkqslElrcF1i45AgNn4bGVg9PtvrdWAvD 2Wa+6/DbvOov0Y1oBhWSsZYYu6IrQlJ8oOXXyUmkujBHS68WF4TPoNqs7xZkpItB8t2E rA2F8Lm+JMq7Tk/dHuOWgJ9inGTD3qytoiG6VAwAuo1v5q8uGomvdnA9Aivg3QIA84qG 7zNA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=Pn4xLHed; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id ck29si9926898edb.236.2020.07.13.20.41.32; Mon, 13 Jul 2020 20:41:56 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=Pn4xLHed; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726675AbgGNDlN (ORCPT + 99 others); Mon, 13 Jul 2020 23:41:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:51326 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726432AbgGNDlN (ORCPT ); Mon, 13 Jul 2020 23:41:13 -0400 Received: from sol.localdomain (c-107-3-166-239.hsd1.ca.comcast.net [107.3.166.239]) (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 67C8D20890; Tue, 14 Jul 2020 03:41:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594698072; bh=SPL3nkj9HvC2j7rtwl00nNXwS53s+StgAz1Rltp3OXE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Pn4xLHed5UErZazjYs75fzvgnaYZ3py3NH+VTIX724EC9TUqwdfrEv0jCtI5x3vj2 EcUQBE7VdW1zx031C74H8IiVcL3J+EpURqyQwsT7kCDHC7vukx4ZThuUXuj41Abqg/ EdHFmTdurMMLft9g//TwoWhWD6R5YzJPHJLQEJCw= Date: Mon, 13 Jul 2020 20:41:11 -0700 From: Eric Biggers To: Hillf Danton Cc: syzbot , akpm@linux-foundation.org, arve@android.com, christian@brauner.io, devel@driverdev.osuosl.org, gregkh@linuxfoundation.org, hughd@google.com, joel@joelfernandes.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, maco@android.com, syzkaller-bugs@googlegroups.com, tkjos@android.com, Markus Elfring Subject: Re: possible deadlock in shmem_fallocate (4) Message-ID: <20200714034111.GD1696@sol.localdomain> References: <0000000000000b5f9d059aa2037f@google.com> <20200714033252.8748-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200714033252.8748-1-hdanton@sina.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 14, 2020 at 11:32:52AM +0800, Hillf Danton wrote: > > Add FALLOC_FL_NOBLOCK and on the shmem side try to lock inode upon the > new flag. And the overall upside is to keep the current gfp either in > the khugepaged context or not. > > --- a/include/uapi/linux/falloc.h > +++ b/include/uapi/linux/falloc.h > @@ -77,4 +77,6 @@ > */ > #define FALLOC_FL_UNSHARE_RANGE 0x40 > > +#define FALLOC_FL_NOBLOCK 0x80 > + You can't add a new UAPI flag to fix a kernel-internal problem like this. - Eric