From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp153-166.sina.com.cn (smtp153-166.sina.com.cn [61.135.153.166]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F28C3B2BA for ; Mon, 16 Mar 2026 01:19:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=61.135.153.166 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773623985; cv=none; b=kvGTst8GMfB8YE6lq18K3jho6B079K1vYFLExdTDws4BIk4u1ZY0c67zcx9L+8Rt9E7rtfeKIk3xMa8u/CzJlrnREVhsEfBpyzTtbCty2h1anbgDv2ncGAFz47NbJAmNygB1JJmQECpOridYankKfWpDRxFGNcOxuPEefuF1B3k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773623985; c=relaxed/simple; bh=23CAR+CwwPFGMBFc21n24wCZTrnFOHa0D0M3aYMTafg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Si8J1Dd7Yu9TgFtZxxVqKpKc5Q/eqZxnsLrtGWX+QuTE0lG4dxamoGVZsoK25h26xPWevasj4ZF+UOGXjkk2f4pUXr9deZI2Ov17UntNlnm46CtI7JduJZJ0TD3kP3b73goGPu7eg0zBJRLABjtEp+qEPXw4sS4xksUSd8wzsbQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=VrslGOkO; arc=none smtp.client-ip=61.135.153.166 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="VrslGOkO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1773623978; bh=CRmzpEov1IgBmPBS46XTcRyuKONV9Ulq4IgAZsY3VDU=; h=From:Subject:Date:Message-ID; b=VrslGOkOAMks2AU1Vbe3H39evphNWyXlTMQ0iBAQcfDIFsL9QQKmufqDYy9G6BlPM ieDRlcNBdg8TJZKpVAYX7QepyQIG6EOX1nucc1z3+T0MZ9QLhLOLLmOwYzZ/j2bi7n zndzzqycaWOIFYdHCVWn/RpyoN+Km8OQEPYmdsXY= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.144]) by sina.com (10.54.253.33) with ESMTP id 69B75A9F000014F1; Mon, 16 Mar 2026 09:19:29 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 6162546685127 X-SMAIL-UIID: CF63692484AB45E696E32C7EC8F49E69-20260316-091929-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [mm?] possible deadlock in mfill_get_vma Date: Mon, 16 Mar 2026 09:19:18 +0800 Message-ID: <20260316011919.998-1-hdanton@sina.com> In-Reply-To: <69b6fc68.a00a0220.3b25d1.001e.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Sun, 15 Mar 2026 11:37:28 -0700 [thread overview] > Hello, > > syzbot found the following issue on: > > HEAD commit: b84a0ebe421c Add linux-next specific files for 20260313 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=131ab8da580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=e7280ad1f68b2dce > dashboard link: https://syzkaller.appspot.com/bug?extid=c473aa669b5e8a6f48d2 > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126c98ba580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1644a2d6580000 #syz test --- x/mm/userfaultfd.c +++ y/mm/userfaultfd.c @@ -217,6 +217,7 @@ static int mfill_get_vma(struct mfill_st dst_vma = uffd_mfill_lock(ctx->mm, state->dst_start, state->len); if (IS_ERR(dst_vma)) return PTR_ERR(dst_vma); + state->vma = dst_vma; /* * If memory mappings are changing because of non-cooperative --