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mm, dev_pagemap: Do not clear ->mapping on final put

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commit 2fa147bdbf672c53386a8f5f2c7fe358004c3ef8 upstream.

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>
Acked-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dan Williams 2018-07-13 21:50:01 -07:00 committed by Greg Kroah-Hartman
parent ff1663fc94
commit 5ad671c852
2 changed files with 2 additions and 1 deletions
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1
kernel/memremap.c
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@ -355,7 +355,6 @@ 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);

2
mm/hmm.c
View File

@ -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);
}