From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from elcheapo.mm12.xyz (elcheapo.mm12.xyz [148.135.104.117]) (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 1CA23171A7; Fri, 10 May 2024 03:53:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.135.104.117 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715313226; cv=none; b=qzGWwzkQuq3yDjUQWqhhND2pRWoy4OAmouOgsy1R81YMuZNoJ/VKNJPkgMXLT9sPouVtFIg0rMPblu+GbPXNY/v7nqQHF0R33fhtzzpJmA8LQq6EV8a8P5TtgtRe+/NNcRr9xHHzMZ0Zc1u22kZnxz7r4PRsMnTNbAzY31Pkdq8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715313226; c=relaxed/simple; bh=y7BXUOx/dAVhQLguT838TRDZl0y8vZ5eIRRG8rxR2/k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uBt8Lk6/3i3foqKlYccKTtYO3RVLjJocr0GezF8u08RnZ4jDFb4BmZkSR6NUg75pXnwdwh3zWyn15G7Lc9Z2ufwFWxgBSTPy/gDLRmkEMzG0WZdvmqsy7Bedh+mAV0LC0RY6p4Bh+D6pBHUiGxQ/jPU6thTdzga72IneP49jSCM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mm12.xyz; spf=pass smtp.mailfrom=mm12.xyz; dkim=pass (2048-bit key) header.d=mm12.xyz header.i=@mm12.xyz header.b=ihVippyL; arc=none smtp.client-ip=148.135.104.117 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mm12.xyz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mm12.xyz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mm12.xyz header.i=@mm12.xyz header.b="ihVippyL" Received: from scala.mm12.xyz by elcheapo.mm12.xyz (Postfix) with ESMTPSA id 672C31F46E; Thu, 9 May 2024 23:46:20 -0400 (EDT) Received: by scala.mm12.xyz (Postfix, from userid 1000) id 61AD4180437; Thu, 9 May 2024 23:46:18 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mm12.xyz; s=mail; t=1715312778; bh=y7BXUOx/dAVhQLguT838TRDZl0y8vZ5eIRRG8rxR2/k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ihVippyLA5SdmGURV5AfqHgDxPYz0rsg1xW6miwecMyyZwh11gmKB3LFS0jKIn6kF 3pYD+g3uAtWJCIgxpl4eOLDcyNHgp8TlFVVLXyBzAyPkTucgRk5sjV6H4JldRHV0Yl tYD7Lc9RJeb5NTdHQ9sBzdLEwgwz6tQIkRf8OU6c+LdRDdqJOD2zIfC1f22AW861po wsFERbhND+1dJmyPjy7q/iRqH/dOtacE/vog8+kM2m4VNwxmOLqc40h4ZRQyU7JJF9 ctzvbW0ze5eXkLYORxKlBcLdhDxReLQl7dDa+OqNmhYvSv1flbblSGZ0UiTYMutTir MkKEs62uT3xLQ== Date: Thu, 9 May 2024 23:46:18 -0400 From: Matthew Mirvish To: Kuan-Wei Chiu Cc: Kent Overstreet , Coly Li , Linux Kernel Mailing List , Linux Next Mailing List Subject: Re: linux-next: manual merge of the refactor-heap tree with the block tree Message-ID: <20240510034618.GA3161190@mm12.xyz> References: <20240509152745.08af752f@canb.auug.org.au> Precedence: bulk X-Mailing-List: linux-next@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, May 10, 2024 at 11:07:11AM +0800, Kuan-Wei Chiu wrote: > On Thu, May 09, 2024 at 07:16:31PM -0400, Kent Overstreet wrote: > > On Fri, May 10, 2024 at 06:44:29AM +0800, Kuan-Wei Chiu wrote: > > > On Thu, May 09, 2024 at 03:58:57PM -0400, Kent Overstreet wrote: > > > > On Thu, May 09, 2024 at 03:27:45PM +1000, Stephen Rothwell wrote: > > > > > Hi all, > > > > > > > > > > Today's linux-next merge of the refactor-heap tree got conflicts in: > > > > > > > > > > drivers/md/bcache/bset.c > > > > > drivers/md/bcache/bset.h > > > > > drivers/md/bcache/btree.c > > > > > drivers/md/bcache/writeback.c > > > > > > > > > > between commit: > > > > > > > > > > 3a861560ccb3 ("bcache: fix variable length array abuse in btree_iter") > > > > > > > > > > from the block tree and commit: > > > > > > > > > > afa5721abaaa ("bcache: Remove heap-related macros and switch to generic min_heap") > > > > > > > > > > from the refactor-heap tree. > > > > > > > > > > Ok, these conflicts are too extensive, so I am dropping the refactor-heap > > > > > tree for today. I suggest you all get together and sort something out. > > > > > > > > Coli and Kuan, you guys will need to get this sorted out quick if we > > > > want refactor-heap to make the merge window > > > > > > Hi Coli and Kent, > > > > > > If I understand correctly, the reported bug is because we attempted to > > > point (heap)->data to a dynamically allocated memory , but at that time > > > (heap)->data was not a regular pointer but a fixed size array with a > > > length of MAX_BSETS. > > > > > > In my refactor heap patch series, I introduced a preallocated array and > > > decided in min_heap_init() whether the data pointer should point to an > > > incoming pointer or to the preallocated array. Therefore, I am > > > wondering if my patch might have unintentionally fixed this bug? > > > > > > I am unsure how to reproduce the reported issue. Could you assist me in > > > verifying whether my assumption is correct? > > > > This is a merge conflict, not a runtime. Can you rebase onto Coli's > > tree? We'll have to retest. > > Oh, sorry for the misunderstanding I caused. When I mentioned "bug" [1] > earlier, I was referring to the bug addressed in > 3a861560ccb3 ("bcache: fix variable length array abuse in btree_iter"), > not a merge conflict. > > Here are the results after the rebase: > https://github.com/visitorckw/linux.git refactor-heap > > [1]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2039368 The ubuntu kernels build with UBSAN now, and the bug reported is just a UBSAN warning. The original implementation's iterator has a fixed size sets array that is indexed out of bounds when the iterator is allocated on the heap with more space -- the patch restructures it a bit to have a single iterator type with a flexible array and then a larger "stack" type which embeds the iterator along with the preallocated region. I took a brief look at the refactor-heap branch but I'm not entirely sure what's going on with the new min heaps: in the one place where the larger iterators are used (in bch_btree_node_read_done) it doesn't look like the heap is ever initialized (perhaps since the old iter_init wasn't used here because of the special case it got missed in the refactor?) With the new heaps it should be fairly easy to fix though; just change the fill_iter mempool to be allocating only the minheap data arrays and setup iter->heap.data properly with that instead. Hope that helps, Matthew Mirvish > > Regards, > Kuan-Wei