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=-3.8 required=3.0 tests=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 76390C3A5A6 for ; Tue, 27 Aug 2019 01:55:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4DA8E206BB for ; Tue, 27 Aug 2019 01:55:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728752AbfH0BzC (ORCPT ); Mon, 26 Aug 2019 21:55:02 -0400 Received: from bilbo.ozlabs.org ([203.11.71.1]:40765 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727646AbfH0BzC (ORCPT ); Mon, 26 Aug 2019 21:55:02 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 46HX4f0vmjz9s00; Tue, 27 Aug 2019 11:54:58 +1000 (AEST) From: Michael Ellerman To: David Sterba , Nikolay Borisov Cc: dsterba@suse.cz, Christophe Leroy , erhard_f@mailbox.org, Chris Mason , Josef Bacik , David Sterba , Andrew Morton , linux-mm@kvack.org, stable@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2] btrfs: fix allocation of bitmap pages. In-Reply-To: <20190826164646.GX2752@twin.jikos.cz> References: <20190826153757.GW2752@twin.jikos.cz> <20190826164646.GX2752@twin.jikos.cz> Date: Tue, 27 Aug 2019 11:54:57 +1000 Message-ID: <871rx74bke.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Sterba writes: > On Mon, Aug 26, 2019 at 06:40:24PM +0300, Nikolay Borisov wrote: >> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=204371 >> >> Fixes: 69d2480456d1 ("btrfs: use copy_page for copying pages instead of memcpy") >> >> Cc: stable@vger.kernel.org >> >> Signed-off-by: Christophe Leroy >> >> --- >> >> v2: Using kmem_cache instead of get_zeroed_page() in order to benefit from SLAB debugging features like redzone. >> > >> > I'll take this version, thanks. Though I'm not happy about the allocator >> > behaviour. The kmem cache based fix can be backported independently to >> > 4.19 regardless of the SL*B fixes. >> > >> >> +extern struct kmem_cache *btrfs_bitmap_cachep; >> > >> > I've renamed the cache to btrfs_free_space_bitmap_cachep >> > >> > Reviewed-by: David Sterba >> >> Isn't this obsoleted by >> >> '[PATCH v2 0/2] guarantee natural alignment for kmalloc()' ? > > Yeah, but this would add maybe another whole dev cycle to merge and > release. The reporters of the bug seem to care enough to identify the > problem and propose the fix so I feel like adding the btrfs-specific fix > now is a little favor we can afford. > > The bug is reproduced on an architecture that's not widely tested so > from practical POV I think this adds more coverage which is desirable. Thanks. cheers