From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f200.google.com (mail-yw0-f200.google.com [209.85.161.200]) by kanga.kvack.org (Postfix) with ESMTP id 6C5B66B0038 for ; Wed, 31 Aug 2016 17:08:39 -0400 (EDT) Received: by mail-yw0-f200.google.com with SMTP id c67so18630799ywe.1 for ; Wed, 31 Aug 2016 14:08:39 -0700 (PDT) Received: from omr2.cc.vt.edu (omr2.cc.ipv6.vt.edu. [2607:b400:92:8400:0:33:fb76:806e]) by mx.google.com with ESMTPS id d68si1379687qkb.79.2016.08.31.14.08.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Aug 2016 14:08:38 -0700 (PDT) Subject: Re: [PATCH] mm:Avoid soft lockup due to possible attempt of double locking object's lock in __delete_object From: Valdis.Kletnieks@vt.edu In-Reply-To: <20160831075421.GA15732@e104818-lin.cambridge.arm.com> References: <1472582112-9059-1-git-send-email-xerofoify@gmail.com> <20160831075421.GA15732@e104818-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1472677706_2066P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Wed, 31 Aug 2016 17:08:26 -0400 Message-ID: <33981.1472677706@turing-police.cc.vt.edu> Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas Cc: Nicholas Krause , linux-mm@kvack.org, linux-kernel@vger.kernel.org --==_Exmh_1472677706_2066P Content-Type: text/plain; charset=us-ascii On Wed, 31 Aug 2016 08:54:21 +0100, Catalin Marinas said: > On Tue, Aug 30, 2016 at 02:35:12PM -0400, Nicholas Krause wrote: > > This fixes a issue in the current locking logic of the function, > > __delete_object where we are trying to attempt to lock the passed > > object structure's spinlock again after being previously held > > elsewhere by the kmemleak code. Fix this by instead of assuming > > we are the only one contending for the object's lock their are > > possible other users and create two branches, one where we get > > the lock when calling spin_trylock_irqsave on the object's lock > > and the other when the lock is held else where by kmemleak. > > Have you actually got a deadlock that requires this fix? Almost certainly not, but that's never stopped Nicholas before. He's a well-known submitter of bad patches, usually totally incorrect, not even compile tested. He's infamous enough that he's not allowed to post to any list hosted at vger. --==_Exmh_1472677706_2066P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Comment: Exmh version 2.5 07/13/2001 iQIVAwUBV8dHSgdmEQWDXROgAQIHSg/+NVg6jIsWvrJ9rciYZHHN1kDWgTIpKMf5 /k+QfaQFwjbVez/0xyThM/yBhovrPWztg2ki9zdA3wqoAKRm2QhrzhWFDYx/COzW DTizXCbtbRkFdqXqGLRvYB+jruGPP2A7hzydNmPYRsg+PaTb7xwlr8lrhzJPqknA jNVvWclbZbXNoMDQVnyxJB/mGg82SfrosFzgymJ3A4ghy6nFT2OqGUEI+dlFJ4dJ MHnrXtOaWHLGroD6jOakyyXY6vxeU9woJSbde1dzNtLabQcVOcCW8wuE0lzRjEYB U6MfokZeO2eFj8xt8VeNaRzuv54R6H04IyY7GYirAEDzlVJ7vF73OcedVkdpCWaL Fo6v4uU6gnEx5reJ8ERucKbAoZrHcNObHnaAOruWwdItWn270N7p+KSThDpd1sWJ SJjQKb7EDSWvctgKYxFND64hNbKki8LH35jZtbu9Xz6oqXt6pT2zLSeCBJ6HSc4H 2OVs1Js0l0i6XxCExqJufLK+GZ0WCD53znUJ/UlO+gBZjLTdSRJZ2ZVmcGSZm1yh Hk9nyHaMTxI0o+d+jyc0f6CvkBAntwctZw7VmBy7nFpcmbl+b9/heVl2VFko6kWc j1YNNS6UBwpPQYTCNW77N6S/xmUMsveHluldyXoYu/mi+79hXvShBmKV70gY6UR4 sfDHud3xCJI= =8Wg2 -----END PGP SIGNATURE----- --==_Exmh_1472677706_2066P-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org