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

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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: d2c997c0f1 ("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>
This commit is contained in:
Dan Williams 2018-07-13 21:50:01 -07:00 • committed by Dave Jiang
parent 86a66810ba
commit 2fa147bdbf
2 changed files with 2 additions and 1 deletions
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1
kernel/memremap.c
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@ -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);

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);
}