From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) (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 2DF992E3E1; Fri, 2 Feb 2024 16:31:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=167.114.26.122 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706891523; cv=none; b=Co3cJlzmd+RTVYVfTB6wiAIP7aXfPmajB5QYyuMvh1B1KDtui+VlvxoHnHZwcid+nSqGqNH8GRbeCrEmNCzVEdDIMRWgcH0C85RMv54Q4hDs+JHl7Vj+CAAdSm4aSzXhQ/jUtokeeSy8wBrVJq0Bg5dRVizeNMv9FzEauUd0PPQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706891523; c=relaxed/simple; bh=yma4nylgOoLjTOHrYgozp3WCHDCZs0kwIUYe+i7FJY8=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=XqaD8fldPUquXzFupiu5ohZsX1xAt5iejh+/6lyBanVhJ/44HIoH0vZO6+EUZDymuZZCFEBOqIkQeK6tLMqlIGtg1A/giLsAEeUUId9ZZ4H2TkypQnGQMS6E5pxDHoVhgLQinPzCAo6urW+NQInBaphmzc6ecYn22q1QTCa99cY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=jU5wubxj; arc=none smtp.client-ip=167.114.26.122 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="jU5wubxj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1706891519; bh=yma4nylgOoLjTOHrYgozp3WCHDCZs0kwIUYe+i7FJY8=; h=Date:Subject:From:To:Cc:References:In-Reply-To:From; b=jU5wubxjeRgWqLh+oXgXkt9L6ToIU6aLtIv74J33D94Z1bAuwUkYMDh43wTpgdlwk ircon1WeA8O1VoQha723YG13bkUh50GNf7CmEu+/24b34xifpcw4D1fgeDOPHgVIIJ jElb/7siEE49WZijpvj972viuZFA8YKRa2ImjRcEa53ZNXFUb4t5y6qyaTIWAWbO4X uVKOqJy5aChedzSPk82AaYiwsp/3O6f8Uzr6Sw72XEkemnVbTSFWoCR24mWLF/NetX lXurcKAzwiKzhXJX6flQLy6YgSDzTBoEnGPBZNJVJqHrjIA0JXKpYY22SQ9Si5VeJT mK+yKNhrX75og== Received: from [172.16.0.134] (192-222-143-198.qc.cable.ebox.net [192.222.143.198]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4TRLrt5bFczX6S; Fri, 2 Feb 2024 11:31:58 -0500 (EST) Message-ID: Date: Fri, 2 Feb 2024 11:32:00 -0500 Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v3 2/4] dax: Check for data cache aliasing at runtime Content-Language: en-US From: Mathieu Desnoyers To: Dan Williams , Arnd Bergmann , Dave Chinner Cc: linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds , linux-mm@kvack.org, linux-arch@vger.kernel.org, Vishal Verma , Dave Jiang , Matthew Wilcox , Russell King , nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, dm-devel@lists.linux.dev References: <20240131162533.247710-1-mathieu.desnoyers@efficios.com> <20240131162533.247710-3-mathieu.desnoyers@efficios.com> <65bab567665f3_37ad2943c@dwillia2-xfh.jf.intel.com.notmuch> <0a38176b-c453-4be0-be83-f3e1bb897973@efficios.com> <65bac71a9659b_37ad29428@dwillia2-xfh.jf.intel.com.notmuch> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024-02-01 10:44, Mathieu Desnoyers wrote: > On 2024-01-31 17:18, Dan Williams wrote: [...] >> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c >> index 5f1be1da92ce..11053a70f5ab 100644 >> --- a/fs/fuse/virtio_fs.c >> +++ b/fs/fuse/virtio_fs.c >> @@ -16,6 +16,7 @@ >>   #include >>   #include >>   #include >> +#include >>   #include >>   #include "fuse_i.h" >> @@ -795,8 +796,11 @@ static void virtio_fs_cleanup_dax(void *data) >>       put_dax(dax_dev); >>   } >> +DEFINE_FREE(cleanup_dax, struct dax_dev *, if (!IS_ERR_OR_NULL(_T)) >> virtio_fs_cleanup_dax(_T)) >> + >>   static int virtio_fs_setup_dax(struct virtio_device *vdev, struct >> virtio_fs *fs) > > So either I'm completely missing how ownership works in this function, or > we should be really concerned about the fact that it does no actual > cleanup of anything on any error. [...] > > Here what I'm seeing so far: > > - devm_release_mem_region() is never called after > devm_request_mem_region(). Not >   on error, neither on teardown, > - pgmap is never freed on error after devm_kzalloc. I was indeed missing something: the devm_ family of functions keeps ownership at the device level, so we would not need explicit teardown. > >>   { >> +    struct dax_device *dax_dev __free(cleanup_dax) = NULL; >>       struct virtio_shm_region cache_reg; >>       struct dev_pagemap *pgmap; >>       bool have_cache; >> @@ -804,6 +808,15 @@ static int virtio_fs_setup_dax(struct >> virtio_device *vdev, struct virtio_fs *fs) >>       if (!IS_ENABLED(CONFIG_FUSE_DAX)) >>           return 0; >> +    dax_dev = alloc_dax(fs, &virtio_fs_dax_ops); >> +    if (IS_ERR(dax_dev)) { >> +        int rc = PTR_ERR(dax_dev); >> + >> +        if (rc == -EOPNOTSUPP) >> +            return 0; >> +        return rc; >> +    } > > What is gained by moving this allocation here ? I'm still concerned about moving the call to alloc_dax() before the setup of the memory region it will use. Are those completely independent ? > >> + >>       /* Get cache region */ >>       have_cache = virtio_get_shm_region(vdev, &cache_reg, >>                          (u8)VIRTIO_FS_SHMCAP_ID_CACHE); >> @@ -849,10 +862,7 @@ static int virtio_fs_setup_dax(struct >> virtio_device *vdev, struct virtio_fs *fs) >>       dev_dbg(&vdev->dev, "%s: window kaddr 0x%px phys_addr 0x%llx len >> 0x%llx\n", >>           __func__, fs->window_kaddr, cache_reg.addr, cache_reg.len); >> -    fs->dax_dev = alloc_dax(fs, &virtio_fs_dax_ops); >> -    if (IS_ERR(fs->dax_dev)) >> -        return PTR_ERR(fs->dax_dev); >> - >> +    fs->dax_dev = no_free_ptr(dax_dev); >>       return devm_add_action_or_reset(&vdev->dev, virtio_fs_cleanup_dax, >>                       fs->dax_dev); >>   } > [...] Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com