From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Dan Williams <dan.j.williams@intel.com>,
Arnd Bergmann <arnd@arndb.de>, Dave Chinner <david@fromorbit.com>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Matthew Wilcox <willy@infradead.org>,
Russell King <linux@armlinux.org.uk>,
nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org,
linux-fsdevel@vger.kernel.org, dm-devel@lists.linux.dev
Subject: Re: [RFC PATCH v3 2/4] dax: Check for data cache aliasing at runtime
Date: Fri, 2 Feb 2024 11:32:00 -0500 [thread overview]
Message-ID: <da4c7c2c-0400-40d7-8263-22d284ecca8c@efficios.com> (raw)
In-Reply-To: <f1d14941-2d22-452a-99e6-42db806b6d7f@efficios.com>
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 <linux/fs_context.h>
>> #include <linux/fs_parser.h>
>> #include <linux/highmem.h>
>> +#include <linux/cleanup.h>
>> #include <linux/uio.h>
>> #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
next prev parent reply other threads:[~2024-02-02 16:31 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-31 16:25 [RFC PATCH v3 0/4] Introduce cpu_dcache_is_aliasing() to fix DAX regression Mathieu Desnoyers
2024-01-31 16:25 ` [RFC PATCH v3 1/4] dm: Treat alloc_dax failure as non-fatal Mathieu Desnoyers
2024-01-31 16:25 ` [RFC PATCH v3 2/4] dax: Check for data cache aliasing at runtime Mathieu Desnoyers
2024-01-31 21:02 ` Dan Williams
2024-01-31 21:39 ` Mathieu Desnoyers
2024-01-31 22:18 ` Dan Williams
2024-02-01 15:44 ` Mathieu Desnoyers
2024-02-02 14:40 ` Mathieu Desnoyers
2024-02-02 16:32 ` Mathieu Desnoyers [this message]
2024-02-02 17:37 ` Dan Williams
2024-02-02 19:29 ` Mathieu Desnoyers
2024-02-02 19:41 ` Dan Williams
2024-02-02 20:02 ` Mathieu Desnoyers
2024-02-02 20:14 ` Dan Williams
2024-02-02 20:18 ` Mathieu Desnoyers
2024-01-31 16:25 ` [RFC PATCH v3 3/4] Introduce cpu_dcache_is_aliasing() across all architectures Mathieu Desnoyers
2024-01-31 17:17 ` Christoph Hellwig
2024-01-31 17:59 ` Mathieu Desnoyers
2024-01-31 20:42 ` Dan Williams
2024-01-31 16:25 ` [RFC PATCH v3 4/4] dax: Fix incorrect list of data cache aliasing architectures Mathieu Desnoyers
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