From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: jhubbard@nvidia.com, "Jan Kara" <jack@suse.cz>,
"Christoph Hellwig" <hch@lst.de>,
"Jérôme Glisse" <jglisse@redhat.com>,
linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: Cleanup __put_devmap_managed_page() vs ->page_free()
Date: Thu, 14 Nov 2019 08:19:03 +0100 [thread overview]
Message-ID: <20191114071903.GA26307@lst.de> (raw)
In-Reply-To: <157368992671.2974225.13512647385398246617.stgit@dwillia2-desk3.amr.corp.intel.com>
On Wed, Nov 13, 2019 at 04:07:22PM -0800, Dan Williams wrote:
> static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
> {
> - if (!pgmap->ops || !pgmap->ops->page_free) {
> + if (!pgmap->ops || (pgmap->type == MEMORY_DEVICE_PRIVATE
> + && !pgmap->ops->page_free)) {
I don't think this check is correct. You only want the the ops null check
or MEMORY_DEVICE_PRIVATE as well now, i.e.:
if (pgmap->type == MEMORY_DEVICE_PRIVATE &&
(!pgmap->ops || !pgmap->ops->page_free)) {
> @@ -476,10 +471,17 @@ void __put_devmap_managed_page(struct page *page)
> * handled differently or not done at all, so there is no need
> * to clear page->mapping.
> */
> - if (is_device_private_page(page))
> - page->mapping = NULL;
> + if (is_device_private_page(page)) {
> + /* Clear Active bit in case of parallel mark_page_accessed */
This adds a > 80 char line. But that whole flow of the function seems
rather odd now.
Why can't we do:
if (count == 0) {
__put_page(page);
} else if (is_device_private_page(page)) {
__ClearPageActive(page);
__ClearPageWaiters(page);
mem_cgroup_uncharge(page);
page->mapping = NULL;
page->pgmap->ops->page_free(page);
} else {
wake_up_var(&page->_refcount);
}
(except for the fact that I don't get the point of calling __put_page
on a refcount of zero, but that is separate from this patch).
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: jhubbard@nvidia.com, "Jan Kara" <jack@suse.cz>,
"Christoph Hellwig" <hch@lst.de>,
"Ira Weiny" <ira.weiny@intel.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: Cleanup __put_devmap_managed_page() vs ->page_free()
Date: Thu, 14 Nov 2019 08:19:03 +0100 [thread overview]
Message-ID: <20191114071903.GA26307@lst.de> (raw)
In-Reply-To: <157368992671.2974225.13512647385398246617.stgit@dwillia2-desk3.amr.corp.intel.com>
On Wed, Nov 13, 2019 at 04:07:22PM -0800, Dan Williams wrote:
> static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
> {
> - if (!pgmap->ops || !pgmap->ops->page_free) {
> + if (!pgmap->ops || (pgmap->type == MEMORY_DEVICE_PRIVATE
> + && !pgmap->ops->page_free)) {
I don't think this check is correct. You only want the the ops null check
or MEMORY_DEVICE_PRIVATE as well now, i.e.:
if (pgmap->type == MEMORY_DEVICE_PRIVATE &&
(!pgmap->ops || !pgmap->ops->page_free)) {
> @@ -476,10 +471,17 @@ void __put_devmap_managed_page(struct page *page)
> * handled differently or not done at all, so there is no need
> * to clear page->mapping.
> */
> - if (is_device_private_page(page))
> - page->mapping = NULL;
> + if (is_device_private_page(page)) {
> + /* Clear Active bit in case of parallel mark_page_accessed */
This adds a > 80 char line. But that whole flow of the function seems
rather odd now.
Why can't we do:
if (count == 0) {
__put_page(page);
} else if (is_device_private_page(page)) {
__ClearPageActive(page);
__ClearPageWaiters(page);
mem_cgroup_uncharge(page);
page->mapping = NULL;
page->pgmap->ops->page_free(page);
} else {
wake_up_var(&page->_refcount);
}
(except for the fact that I don't get the point of calling __put_page
on a refcount of zero, but that is separate from this patch).
next prev parent reply other threads:[~2019-11-14 7:19 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-14 0:07 [PATCH] mm: Cleanup __put_devmap_managed_page() vs ->page_free() Dan Williams
2019-11-14 0:07 ` Dan Williams
2019-11-14 0:39 ` John Hubbard
2019-11-14 0:39 ` John Hubbard
2019-11-14 0:47 ` Dan Williams
2019-11-14 0:47 ` Dan Williams
2019-11-14 7:23 ` Christoph Hellwig
2019-11-14 7:23 ` Christoph Hellwig
2019-11-14 7:26 ` John Hubbard
2019-11-14 7:26 ` John Hubbard
2019-11-14 1:24 ` Jerome Glisse
2019-11-14 1:24 ` Jerome Glisse
2019-11-14 7:19 ` Christoph Hellwig [this message]
2019-11-14 7:19 ` Christoph Hellwig
2019-11-14 7:25 ` Dan Williams
2019-11-14 7:25 ` Dan Williams
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