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SubjectRe: [PATCH v6 06/13] mm, dev_pagemap: Do not clear ->mapping on final put
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Jerome,
Is it possible to get an ack for this? Thanks!

On 07/13/2018 09:50 PM, Dan Williams wrote:
> MEMORY_DEVICE_FS_DAX relies on typical page semantics whereby ->mapping
> is only ever cleared by truncation, not final put.
>
> Without this fix dax pages may forget their mapping association at the
> end of every page pin event.
>
> Move this atypical behavior that HMM wants into the HMM ->page_free()
> callback.
>
> Cc: <stable@vger.kernel.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Jérôme Glisse <jglisse@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Fixes: d2c997c0f145 ("fs, dax: use page->mapping...")
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> kernel/memremap.c | 1 -
> mm/hmm.c | 2 ++
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/memremap.c b/kernel/memremap.c
> index 5857267a4af5..62603634a1d2 100644
> --- a/kernel/memremap.c
> +++ b/kernel/memremap.c
> @@ -339,7 +339,6 @@ void __put_devmap_managed_page(struct page *page)
> __ClearPageActive(page);
> __ClearPageWaiters(page);
>
> - page->mapping = NULL;
> mem_cgroup_uncharge(page);
>
> page->pgmap->page_free(page, page->pgmap->data);
> diff --git a/mm/hmm.c b/mm/hmm.c
> index de7b6bf77201..f9d1d89dec4d 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -963,6 +963,8 @@ static void hmm_devmem_free(struct page *page, void *data)
> {
> struct hmm_devmem *devmem = data;
>
> + page->mapping = NULL;
> +
> devmem->ops->free(devmem, page);
> }
>
>
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
>

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